Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: Albatross on 25 August 2008, 22:19:54
-
0170 & 0173
I used to get the old chestnut 0420 code and then moved the secondary lambda sensors to behind the main CATs which has resolved that, but now I have the 0170 & 0173.
Why? Are these for the front lambda sensors or something?
What do I try now?
-
Fuel Trim
I wonder if the block learn values need resetting now you've moved those sensors? :-/
Regardless, the block learn values should 'learn' over time anyway.
-
Incidently did you have those codes before you moved the lambdas and have you replaced them with new ones?
-
No, I had 0420 and 0430 before. That code cleared when I moved the secondary (further back pair) lambda sensors back behind the main cats rather than between the pre-cats and the main cats.
I had to replace one of the lambda sensors as it was rusted into the thread so I just left it in there and cut the wire and put a new one into the new boss behind the main cat when I had the custom "cat-back" exhaust made.
-
Fuel trim codes are generated when the ECU can't compensate the fuel / air ratio against the readings the Lambdas are giving.
When are the codes generated? Cold start or normal operating temperature?
Best person to speak to would be Kevin Wood.
-
Fuel trim codes are generated when the ECU can't compensate the fuel / air ratio against the readings the Lambdas are giving.
When are the codes generated? Cold start or normal operating temperature?
Best person to speak to would be Kevin Wood.
Thanks Andy; I've sent him a PM, let's see what advice he can add.
-
You can call me James if you like but my name is actually Andy!!!!!! :y ;D
-
Fuel trim should be unrelated to the second lambda sensors as only the pre-cat lambda sensors have an influence on this, or so I believe. :-/ You never know..
Does anyone have the actual definition of these error codes?
Kevin
-
I don't have the true definition, but I'm told they're to do with fuel trim.
There's a bit of history to this one...
I used to get 0420 & 0430 which was a notification that the difference between the readings at the 1st lambda sensor and the 2nd was not cleaned enough which indicated that the "pre-cats" were a bit tired. This is very common on the 2.6 and 3.2 litre engines.
I then had a stainless (quiet) cat-back exhaust made and whilst they built it thay added 2 new lambda sensor bosses behind the main cats and moved the secondary sensors further back so that both the pre-cat and the main cats were cleaning the air between the two sensors on both sides.
This has cured the 0420 & 0430 codes which is some success, but now I'm getting these two new codes 0170 & 0173. Someone (above) has said that this is to do with lambda sensor or fuel trim issues, and after doing a search on here on "0173" I have seen evidence to confirm, but I'm now a bit lost. :-/
-
Kevin,
You have a PM
-
Question.......did the new codes appear immediately after the work was done or some time after?
The definitions are as follows:
P0170 - Fuel trim malfunction (Bank 1)
P0173 - Fuel trim malfunction (Bank 2)
Now, this can be affected by the exhaust!
Also, worth checking fuel filter, inlet system for airleaks etc.
-
Question.......did the new codes appear immediately after the work was done or some time after?
The definitions are as follows:
P0170 - Fuel trim malfunction (Bank 1)
P0173 - Fuel trim malfunction (Bank 2)
Now, this can be affected by the exhaust!
Also, worth checking fuel filter, inlet system for airleaks etc.
Did the new codes appear immediately after the work was done or some time after?
I'm not sure, but the new exhaust hasn't been on that long (2 months) so I'd consider "some time after" to be as good as immediate. I don't know how long the error message has been ther because my EML buld went IMMEDIATELY when the exhaust was changed and lambda sensors moved and I only became aware when the "service" light showed for a while.
Now, this can be affected by the exhaust!
Bugger.
Are there any other symptoms or ways of checking?
-
I would say it's worth getting a Tech 2 or a ELM code reader on it and having a look at the live data, specifically the fuel trim values, and lambda sensor behaviour, to see what's going on.
The new exhaust could be affecting the fuel trims by virtue of being more or less free-flowing but I wouldn't expect it to be significant enough to put the EML on. If there are air leaks upstream of the main lambda sensors, or induction air leaks, fuel system problems, etc. this would be much more significant. That this occurred exactly when the exhaust was changed is a bit of a coincidence but if the fuel trims were already just below the limits maybe the slight effect the new exhaust had has pushed them over the limits.
The fact that both banks are complaining makes me think it's something common to both - fuel supply or air leaks.
I wouldn't expect this to be related to the post-cat lambda sensor relocation because they have no input to the fuel trim, they are for monitoring cat performance only.
Kevin
-
Very useful thanks.
I have to go to Bicester this afternoon, so I wonder if TB is around and prepared to plug in and give it a once over?
I'll drop him a PM too to see if he is able.
Thanks
Nathan
-
Very useful thanks.
I have to go to Bicester this afternoon, so I wonder if TB is around and prepared to plug in and give it a once over?
I'll drop him a PM too to see if he is able.
Thanks
Nathan
yes, I'm in all day.
-
Cheers buddy, I just tried to call you
-
Cheers buddy, I just tried to call you
Opps, sorry, tidying up the garage.... ....I'm in though.
-
OK, I fixed the front multiram, but as far as I can see, the lamdas look fine, fuel trim looks plausible....
If anyone else with TIS care to take a peek at the snapshot?
http://theboy.omegaowners.com/tech2snapshots/ALBATROSS.SUR
-
Thanks TB; pleasure as always.
Nathan
-
OK, I fixed the front multiram, but as far as I can see, the lamdas look fine, fuel trim looks plausible....
If anyone else with TIS care to take a peek at the snapshot?
http://theboy.omegaowners.com/tech2snapshots/ALBATROSS.SUR
and for anyone who has never tried before, put the snapshot file in
c:\program files\cosids\data\snapshot :y
-
Could do with a capture triggered off the fault code really....
Heres the graph anyway which looks ok (will analyse it further later when I have more time)
(http://i23.photobucket.com/albums/b394/Marks_DTM_Calib/Albatross.jpg)
-
Could do with a capture triggered off the fault code really....
Heres the graph anyway which looks ok (will analyse it further later when I have more time)
(http://i23.photobucket.com/albums/b394/Marks_DTM_Calib/Albatross.jpg)
I couldn't get it to reproduce the fault. Albatross doesn't know when it happens either, due to a blown EML! (I didn't have a spare, else I would have fixed that)
-
That graph looks great, but what software would I need to be able to read the file and turn it into a graph.
And what does the graph actually mean?
-
That graph looks great, but what software would I need to be able to read the file and turn it into a graph.
And what does the graph actually mean?
TIS is the software, and the graph means - to my eyes - that it all looks OK :-/
-
That graph looks great, but what software would I need to be able to read the file and turn it into a graph.
And what does the graph actually mean?
TIS is the software, and the graph means - to my eyes - that it all looks OK :-/
I'm guessing the fault is intermittent or only occurs during a certain engine operating condition, which wasn't reproduced during that test.
I would say take it for a test drive logging the short and long term fuel trims. I'm guessing there's a set of circumstances where these are getting out of limits and knowing the circumstances (high / low inlet vacuum, high / low fuel demand, One bank / both banks together etc.) would be a useful pointer.
Kevin
-
That graph looks great, but what software would I need to be able to read the file and turn it into a graph.
And what does the graph actually mean?
TIS is the software, and the graph means - to my eyes - that it all looks OK :-/
I'm guessing the fault is intermittent or only occurs during a certain engine operating condition, which wasn't reproduced during that test.
I would say take it for a test drive logging the short and long term fuel trims. I'm guessing there's a set of circumstances where these are getting out of limits and knowing the circumstances (high / low inlet vacuum, high / low fuel demand, One bank / both banks together etc.) would be a useful pointer.
Kevin
Agreed, though handy to put bulb back in to see how often it does it.
Tech2, oddly, isn't ideal for long distance live data check, due to length of its connector, and location of Omega diags port. Also, quality of diags port not great, so occasional disconnections as well.
-
Tech2, oddly, isn't ideal for long distance live data check, due to length of its connector, and location of Omega diags port. Also, quality of diags port not great, so occasional disconnections as well.
I keep meaning to knock up a program to do this with my ELM lead so I can figure out what's going on with the post-cat lambdas.
Kevin
-
Tech2, oddly, isn't ideal for long distance live data check, due to length of its connector, and location of Omega diags port. Also, quality of diags port not great, so occasional disconnections as well.
I keep meaning to knock up a program to do this with my ELM lead so I can figure out what's going on with the post-cat lambdas.
Kevin
I may be able to help with Tech2 when you get back from hols, if you just need to check the lamdas for a week or 2 ;)
Obviously, I may need a couple of favours in return, one you know about, one you don't ::) :-X
-
Thanks blokes.
What is my best next course of action? (apart from the EML bulb)
-
Right; post rejuvenation:
TB helped me to clear the codes and replace the EML bulb this morning and then Kevin Wood just popped round with a Tech2 this afternoon.
I had some "Intermittent Trim" (0170 & 0173) codes in the 45 mile run home from Jaime's, but the EML light hadn't been triggered.
On a run we checked the live feed with the Tech2 and Kevin Wood. My immediate trims seemed to be running in balance accross either side of the engine at around the 7 - 10% rich i.e. having to compensate by putting extra fuel through. The "long term" trims were up by 24% on both sides.
This seems to be the engine feeling the need to pump more fuel in than the normal trim level.
Possible diagnosis:
Too much air:
- Air leak (as this is consistent from side to side it would need to be quite close to the plenum)
- Better flow through the new stainless free flow exhaust
Not enough fuel:
- Dirty injectors (I'll try some cleaner fliud in the fuel, but I am quite frequent with this)
- Low fuel pressure (I'll get this checked at a garage)
Kevin and I realised that it could be that the free flow exhaust is giving improved air flow and therefore the 3-bar air flow regulator might simply not be man anough to keep with the improved air flow up as standard. Taking that further we felt that it might be worth (after checking for air leaks and cleaning the injectors) that it might be worthwhile considering a 4-bar fuel pressure guage to up the pressure in line with the increased air flow created by the upgraded exhaust.
Car is running like a dream though.
I'll keep the post posted as it were.
Once again, many thanks again to Jaime and Kevin for your help today; much appreciated. :y :y
-
No problem. Was nice to meet you earlier.
Hmm. :-/ Thinking about it, more flow through the exhaust should mean more flow through the MAF which would mean the ECU would give you more fuel anyway, without extra fuel trim.
Long term trim for both banks seemed to be pegged out at +24% and at times under load it was adding another 10% short term. At idle the total trim was only a few percent. Makes me think it might be an air leak or a fuel delivery problem.
I think I will compare live data from my car to that snapshot. See if anything jumps out as being different.
Kevin
-
No problem. Was nice to meet you earlier.
Hmm. :-/ Thinking about it, more flow through the exhaust should mean more flow through the MAF which would mean the ECU would give you more fuel anyway, without extra fuel trim.
Long term trim for both banks seemed to be pegged out at +24% and at times under load it was adding another 10% short term. At idle the total trim was only a few percent. Makes me think it might be an air leak or a fuel delivery problem.
I think I will compare live data from my car to that snapshot. See if anything jumps out as being different.
Kevin
I don't suppose you had a chance to check your readings on your car did you?
I was wondering; do you think that it could even be a very dirty fuel filter?
-
I had a look at your datalog tonight and the fuel trim seems to get worse with increasing load. It's not unreasonable at idle but it's winding on quite a lot at heavier load. Having seen that I think it could well be restricted fuel supply. Either a clogged filter or a lazy fuel pump perhaps.
MAF, and the other sensors seem to be reading roughly what mine do under similar conditions. Nothing jumps out at me as wrong, at least. :-/
Kevin
-
Thanks Kevin,
I'll change the fuel filter this weekend and try to use some motivational management techniques on the pump. ;D
If the fuel filter change doesn't work, what's the next step? How can I diagnose the fuel pump before going to the lengths of replacing it?
I'll get the fuel pressure checked at a garage like you suggested, but I'll wait now until I've changed the filter.
I've seen the maintenance guide on changing the fuel filter, but that's on a 3.2 estate. Is it pretty much the same with a saloon? Do I need to do the "remove the fuse whilst the engine is running" bit that it mentions to drain the fuel lines 1st?
Fuel filter change (Estate) http://www.omegaowners.com/forum/YaBB.pl?num=1177279323
Fuel pump plate renewal http://www.omegaowners.com/forum/YaBB.pl?num=1186065848
-
I would either remove the fuse or loosen the feed pipe union where it connects to the fuel rail under the plenum to relieve the pressure in the fuel system otherwise you're liable to get doused when the filter comes off. Saloon filter is identical, IIRC, and located between the front of the fuel tank and the rear of the diff. Slide under the car just behind the rear offside wheel and look up and you'll see it.
I suspect fuel pressure at idle will be fine, as the fuel trim at idle didn't seem to be going outside sensible limits.
If you still have issues after replacing the filter the thing to do would be to measure the flow rate returning back to the tank. This will tell you how much flow the fuel pump has "in reserve" once it's got the system up to 3 bar of pressure.
Kevin
-
Rather worryingly, I have just found this:
http://newsgroups.derkeiler.com/Archive/Rec/rec.autos.makers.honda/2005-12/msg00732.html
It suggests post-cat Lambda sensors can have an influence on fuel trim on certain engine management systems whereas previously we assumed they were only to monitor cat efficiency. I wonder if relocating them has upset something? :-/
Have you noticed any change in fuel consumption since relocating the Lambda sensors?
Kevin
-
Rather worryingly, I have just found this:
http://newsgroups.derkeiler.com/Archive/Rec/rec.autos.makers.honda/2005-12/msg00732.html
It suggests post-cat Lambda sensors can have an influence on fuel trim on certain engine management systems whereas previously we assumed they were only to monitor cat efficiency. I wonder if relocating them has upset something? :-/
Have you noticed any change in fuel consumption since relocating the Lambda sensors?
Kevin
Yes fuel consumption is Sh!t now :-/
I used 2/3 of a tank going from Bedford to Worcester and back again!
I reckon it looks like the secondary O2S may have to go backto where they were again. What other optons are there? Can the ECU system be remapped so that the O2S sensors are less sensitive and therefore stop complaining 0430 stylee that the pre-cats are tired?
Do you reckon I should consider replacing the pre-cats?
TBH, where I'd really like to get to is to de-cat the car completely and then only refit the main cats on MOT day once a year, but not at the expense of fuel consumption.
What sort of place does this sort of bespoke remapping on a OBDII DBW engine?
-
Hmm. :-/
I wish I could get my head round what's going on. I've been reading through a few patent documents relating to the use of post-cat lambda sensors and they do have a role in calculating fuel trim in some of the schemes. I can only assume that putting a bigger cat in the loop throws the calculations out, but, having said that, your pre-cat lambda sensors look like they're behaving perfectly normally for a closed-loop system with the correct mixture - cycling between lean and rich. :-/ With a load of extra fuel trim they would be indicating a solid "rich".
I think it'd still be worthwhile checking the obvious things like fuel delivery but equally it'd put this one to bed one way or the other to swap the Lambdas back and see if the fuel trim returns to normal. :-/
Kevin
-
To answer your other question, Yes, in theory the code in the ECU could be modified to completely disable the cat efficiency monitoring. The trick would be finding someone who's hacked the ECU code to that level. I suspect it's far less easy on these flash based ECUs than it was on the old M2.7.1 devices that are EPROM based.
A mate of mine used to hang out on http://www.diy-efi.org/ and hacked an older GM ECU to the extent that he is now using a Corvette ECU on a C20XE in a kit car. Unfortunately I don't think anyone is that active anymore.
Kevin
-
I am moving my sensors back to their original position this morning to establish root cause. I'll be clearing tthe codes and will be able to confirm whether my current 0170 & 0173 problem is then replaced by 0420 & 0430 again in the next few days.
I am building up quite a case of evidence on sorting this 0420 pre-cat isue and I WILL FIX IT, but the movement of the secondary O2 sensors has co-incided perfectly with no further 0420 codes and the start of the 0170 codes.
-
watching with interest gents...
can the ecu be re-mapped/hacked to give the correct fuel trim with the 02s in the current(behind big cat) position? Is it a set value or does it "learn"?
As said, interesting to see if problem swaps when 02s returned to original location.
-
watching with interest gents...
can the ecu be re-mapped/hacked to give the correct fuel trim with the 02s in the current(behind big cat) position? Is it a set value or does it "learn"?
As said, interesting to see if problem swaps when 02s returned to original location.
As stated I will be "testing" as of later this morning, but if it transpires to be that the movement back to behind the main cat causes the fuel trim issue then I am considering two options:
- An ECU remap / hack as suggested, but I consider this to be a bit over complex and perhaps expensive.
So, working on the principle of Okham's razor...
- On reading the link that Kevin Wood posted (Click Here (http://newsgroups.derkeiler.com/Archive/Rec/rec.autos.makers.honda/2005-12/msg00732.html)) it seems to me that the fuel trim acts based on the voltage sent back by the secondary O2 sensor. I have an idea which might counteract this: If I were to add a peice of electrickery (I can't remember what they are called, I know it isn't a resistor because that would constantly reduce the voltage, but there is such a thing that "clips" the voltage to a certain amount), this should, in theory, then allow me to stop the higher voltage being sent back to the ECU from the O2 sensor. If the O2 sensor sends more voltage back on higher emmissions then this should work against the 0420/0430 issue with the sensors in the original position, if it is the other way round and voltage sent from the O2 sensor increases as the air in the exhaust is cleaner then this should work agaisnt the fuel trim issue 0170/0173 when the sensors are moved behind the main cat.
I hope that makes sense. I just need to test 1st by moving the sensors back today to be sure about where we're at at the moment and then take it from there with an electronics wizard when I can find one.
-
will you change the fuel filter first? Or after. I suppose if you move the sensors and you have fuel trim AND pre cat codes then... You have a fuel issue? If just a the cat code then the position is relevent to fuel trim...
-
will you change the fuel filter first? Or after. I suppose if you move the sensors and you have fuel trim AND pre cat codes then... You have a fuel issue? If just a the cat code then the position is relevent to fuel trim...
I'm going to move the sensors 1st, so as to isolate each change. That way I won't muddy the waters at all whilst trying to analyse the root cause.
Like you say, if the 0420/0430 & the 0170/0173 all occur when I hve moved them I can then look at fuel filter.
I also need to get the fuel pressure checked, but I'm very confident that that is good and also that there are no air leaks. Reading Kevin's posts above I think that we have eliminated those anyway in a process of his logical reasoning.
-
Sensors now moved back and codes cleared.
Let's see where we go from here...
:)
-
Sensors now moved back and codes cleared.
Let's see where we go from here...
:)
Any bets? Ill have a pound on...
No fuel codes, back to cat codes. ;)
-
Sensors now moved back and codes cleared.
Let's see where we go from here...
:)
Any bets? Ill have a pound on...
No fuel codes, back to cat codes. ;)
No bet from my end I'm afraid as I'm pretty damn sure that's what'll happen too. I know this is resolvable though and I will come up with the final solution.
-
Now here's what I was not expecting.
Sensors in the standard postition and all codes cleared. I take the car out for a good thrash and keep the foot down and ...
wahey the EML light re-appears...
0420, 0430 you're thinking?
Nope :-/
Bloody 0170 and 0173 again. :(
Now that points me back to low fuel pressure, dirty filter, lazy fuel pump or air leak. >:(
On the other hand, that still leaves the distinct prossibility (probability) that moving the sensors did work, because I haven't had a single 0420 or 0430 whilst they were back there. :)
So I need to solve these 0170 & 0173 fuel trim issues on both sides 1st then once I have that settled then I need to start looking at moving the O2 sensors back again. ;)
Or is there some possibility that after having the codes cleared (Cheapo TechII) that there was some residual effect of the "long term fuel trim" readings left in the system that has caused the recurrence of the fault code? All he did was "CLEAR ALL DTS CODES".
Any ideas on where to start? I suppose it is the same answer(s) of "change the fuel filter" and then "get the fuel pressure checked" isn't it? :y
-
I would say change the fuel filter if it's not been done recently.
Oh, and I reckon the cat codes will be back in a day or two.
At least it looks like the fix will work. Just got to find out why the fuel trim problems now. I would say fuel pressure won't be a problem at idle because it was winding up the fuel trim under load. Measuring the flow rate from the return from the rail would be a useful diagnostic step if the filter doesn't help.
Kevin
-
I would say change the fuel filter if it's not been done recently.
Oh, and I reckon the cat codes will be back in a day or two.
At least it looks like the fix will work. Just got to find out why the fuel trim problems now. I would say fuel pressure won't be a problem at idle because it was winding up the fuel trim under load. Measuring the flow rate from the return from the rail would be a useful diagnostic step if the filter doesn't help.
Kevin
Is this what you were talking about when you were here (i.e. a garage can check the pressure) or is this something different?
How can I measure this accurately?
EDIT: Kevin, would a damaged secondary 02 sensor on ONE side possibly cause a fuel trim error on both sides simulataneously? I ask becasue when I was moving the sensors back to the original position yesterday I noticed that the sensor on the near-side bank was a bit scratched just inside the thread (slight flaw in the o2 sensor boss on the new SS exhaust which is now fixed with a round file). The end point where the actual sensor hole is was fine, but I am just checking. I suspect that it is unlikely and we should be looking or something that is common to both sides, and "pre-combustion", due to the symetry of the errors.
-
The problem is, the fuel pressure can only be measured when it's idling.
Looking at the datalog I took, when the engine is idling the fuel trim is OK. It is when we were driving it that it struggled, thus I expect, if it's a fuel system problem the pressure will be OK at idle but will drop off as the demand for fuel increases.
What I was proposing is to remove the return line from the tank or the fuel rail, running the pump and measuring the volume of fuel returned per minte. This is a measure of how much fuel the pump is shifting at rated pressure, rather then whether it can maintain that pressure with very little demand.
Simple things first, though. Try changing the filter.
I'd ve very surprised if you've damaged the Lambda sensor with a burr on the boss thread. You'd get other codes if the sensor was misbehaving anyway.
Kevin
-
OK fuel filter will be changed on Monday and codes cleared again.
I just checked the top panel of the fuel pump, cleaned it off, cleaned all the contacts with cleaner and checked that there were no leaks at the junction between the flat plate and the metal 90o elbow bends. There was a little surface rust, but I cleaned that off and all looks good.
I'll post again with reports after another thrashing with a new fuel filter. What I need to try to achive now is a code 0420 and/or 0430, but no 0170 or 0173 over a period of a few days.
Once I can do that then I can start thinking about moving the secondary O2 sensors back to behind the main cats and clearing the codes.
Then it is another re-test.
Is there anywhere under the bonnet that I should be looking for fuel / air leaks?
JamesV6CDX and I had the plenum off and he re-sealed my cam-covers for me and replaced the cam-belt, water pump and rollers, whilst I cleaned out the plenum and breather pipes. All rubber seals were replaced and were checked for quality before use. The MAF/Plenum gasket was replaced as were both the big (arms thickness) rubber hose elbows which are jubilee clipped to the front of the throttle body / plenum.
We also changed the plugs (the dealer gave me those 4 point plugs). We changed the HT leads too.
Air filter is less than 500 miles old and the box is perectly sealed. Oil and oil filter less than 1000 miles.
-
Kevin,
I've just PM'd you with this same question, but it seems to make sense to post it here as it is somewhat related:
First two assumptions:
Assumption 1:
- I get to the bottom of this fuel trim issue of the codes 0170 and 0173.
Assumption 2:
- Once I have done the above I have reverted to having the secondary 02 sensors behind the main cats and that this solves the original problem of 0420 and 0430 pre-cat deficiency issues.
Question:
- Would I be mad for thinking that I could actually fit 3.0 standard cat sections into my 3.2 exhaust system?
The reason I ask is three-fold:
The first two are Economy & Availability as the single cat sections are both cheaper and more readily available second hand.
The third is increased air-flow out through the exhaust system as I would only have a single cat on each side to contend with.
-
Received by PM...
Thanks as always Kevin. :y
Hi Nathan,
Hmm. Interesting thought. I guess you could. Only thing that might be an issue is that the single large cat might not get up to temperature as quick as the small pre-cat so if there is any monitoring of the warmup cycle it could raise a cat efficiency code. Given that the pre-cats are probably not working well if at all it might not be any different. There is always going to be a bit of "suck it and see" involved in this type of thing, but I'd say it might be worth a try. I'd certainly try a pair of 3.0 cats if my cats failed, put it that way.
Failing that, take out both cats and make up a pipe with a little sports cat each side. I wonder how much more restrictive the twin cat pipes are, if at all?
Kevin
-
Regarding air leaks, etc:
I think you're looking for something upstream of the throttle since fuel trim is positive and gets worse under load (not under vacuum).
I'd check the pipe from the bottom of the throttle body to the fuel pressure regulator. Very difficult with the plenum on but check that the front end is Ok where it turns 90 degrees and in to the bottom of the throttle body (I had a feel under here last weekend and it seemed ok) and also see if you can see / feel it under the back of the plenum as it goes into the FPR.
Then we're left with the TB to multiram pipes which looked OK, multiram to MAF which also looked OK and we're at the MAF now so nothing further upstream matters.
Kevin
-
Thanks Kevin,
Not sure I understand all that, but I'll have a go. I'm not sure what the throttle looks like for starters. :-/
What does the fuel pressure regulator look like and where will I find it?
After consideraton, do you still think that it can't be the increased flow (reduced restriction) of the new stainless cat-back exhaust?
-
Thanks Kevin,
Not sure I understand all that, but I'll have a go. I'm not sure what the throttle looks like for starters. :-/
The throttle body is the cast aluminium block that sits between the plenum and the two elbows. You should find a small breathe out of the bottom of this which runs under the plenum to the fuel pressure regulator. TBH, i doubt it's big enough to greate a significant air leak anyway.
After consideraton, do you still think that it can't be the increased flow (reduced restriction) of the new stainless cat-back exhaust?
I would expect any extra flow would be matched by additional air, which would be measured by the MAF, so at the moment my money is on poor fuel delivery for some reason.
One thing might be interesting: Is average fuel consumption being accurately calculated by the display in the car or does it differ from what you're putting into the tank?
Kevin
-
Thanks for all of that, I'll have a look in daylight tomorrow.
One thing might be interesting: Is average fuel consumption being accurately calculated by the display in the car or does it differ from what you're putting into the tank?
Kevin
Christ on a bike, now you're asking. I never take note of that; I can do now though.
I'll start soon. I'll run her nearly dry and then fill up with Super Unleaded, it should be in the next couple of days. I'll take note of the amount of litres put in, reset all the clocks etc. and then run her for a while, what say 3 or 4 days? I have to nip up to Gateshead this week, so that will give me the opportunity to fill up at least once or twice. :-/.
Then I'll take note of how many litres it is to fill her up again each time and a reading from the odometer and all the clock readings on the CID.
-
Thanks for all of that, I'll have a look in daylight tomorrow.
One thing might be interesting: Is average fuel consumption being accurately calculated by the display in the car or does it differ from what you're putting into the tank?
Kevin
Christ on a bike, now you're asking. I never take note of that; I can do now though.
I'll start soon. I'll run her nearly dry and then fill up with Super Unleaded, it should be in the next couple of days. I'll take note of the amount of litres put in, reset all the clocks etc. and then run her for a while, what say 3 or 4 days? I have to nip up to Gateshead this week, so that will give me the opportunity to fill up at least once or twice. :-/.
Then I'll take note of how many litres it is to fill her up again each time and a reading from the odometer and all the clock readings on the CID.
Yep, reset the avg consumption and odo when you fill up, give it a tank or two, keeping note of what you've put in and see if it is accurate. See if it is injecting as much fuel as it thinks it is. :y
Kevin
-
Will it matter if I have the fuel filter changed during this measuring/reconciliation process?
I think I might try to get the fuel filter done first, codes cleared and then go down to the petrol station.
Would that be the best approach?
-
Watching this thread with interest as I have exactly the same problem with fuel trim issues on both banks, and EML on, I changed the fuel filter a few weeks ago, interestingly I do appear to get the fuel reading from the MID eg range is giving me what is states around town. I have a GS 500 maxscan which I can reset and read the codes, but last time I reset the codes the engine does not like it at all, ad sounds like a pil of poo for a little while until it then eventually settles down, some folks may recall this from the Newent meet. May reset them again today and see what happens, and let you know.
-
Watching this thread with interest as I have exactly the same problem with fuel trim issues on both banks, and EML on, I changed the fuel filter a few weeks ago, interestingly I do appear to get the fuel reading from the MID eg range is giving me what is states around town. I have a GS 500 maxscan which I can reset and read the codes, but last time I reset the codes the engine does not like it at all, ad sounds like a pil of poo for a little while until it then eventually settles down, some folks may recall this from the Newent meet. May reset them again today and see what happens, and let you know.
Hi Mike,
What engine size do you have?
When you say you're getting the same codes, do you mean that you get 0170 & 0173 together?
I don't fully understand some parts of your post there. When you say that "interestingly I do appear to get the fuel reading from the MID eg range is giving me what is states around town." I'm unsure.
Could you clarify this bit for me please?
I'll be changing my fuel filter today, assuming they have one on the shelf at the Vx stealers of course, and clearing the codes.
-
I reset the codes the engine does not like it at all, ad sounds like a pil of poo for a little while until it then eventually settles down, some folks may recall this from the Newent meet. May reset them again today and see what happens, and let you know.
Clearing the codes also appears to reset the fuel trim, so if the car needed a load of fuel trim for some reason, it will suddenly get a rich / lean mixture and run rough until it has established the correct fuel trim again.
Yours is a 2.6, IIRC? Does your scan tool let you see live data values? Can you see what the short term and long term fuel trims are doing when it's running, out of interest?
I'll be changing my fuel filter today, assuming they have one on the shelf at the Vx stealers of course, and clearing the codes.
Yep, give that a try first. :y
Kevin
-
Received by PM...
Thanks as always Kevin. :y
Hi Nathan,
Hmm. Interesting thought. I guess you could. Only thing that might be an issue is that the single large cat might not get up to temperature as quick as the small pre-cat so if there is any monitoring of the warmup cycle it could raise a cat efficiency code. Given that the pre-cats are probably not working well if at all it might not be any different. There is always going to be a bit of "suck it and see" involved in this type of thing, but I'd say it might be worth a try. I'd certainly try a pair of 3.0 cats if my cats failed, put it that way.
Failing that, take out both cats and make up a pipe with a little sports cat each side. I wonder how much more restrictive the twin cat pipes are, if at all?
Kevin
Just a thought, but with the 3.0 litre cat in mind, is it worth moving the pre cat 02s into the old post cat holes on your current cat? Im thinking, in conjunction with the post cats moved behind big cats this would give as close as possible test as to weather the 3.0 cat would work? Might it even work better as that anyway? Or at least give the best location to add 02 bosses on the 3.0 cat?
-
Just a thought, but with the 3.0 litre cat in mind, is it worth moving the pre cat 02s into the old post cat holes on your current cat? Im thinking, in conjunction with the post cats moved behind big cats this would give as close as possible test as to weather the 3.0 cat would work? Might it even work better as that anyway? Or at least give the best location to add 02 bosses on the 3.0 cat?
The pre-cat sensors need to be seeing exhaust gas directly from the engine as it's impossible to measure the actual fuel mixture burning in the engine once the mixture's been through a cat. I can't see any merit in moving the pre-cat sensors, TBH.
Kevin
-
Just a thought, but with the 3.0 litre cat in mind, is it worth moving the pre cat 02s into the old post cat holes on your current cat? Im thinking, in conjunction with the post cats moved behind big cats this would give as close as possible test as to weather the 3.0 cat would work? Might it even work better as that anyway? Or at least give the best location to add 02 bosses on the 3.0 cat?
The pre-cat sensors need to be seeing exhaust gas directly from the engine as it's impossible to measure the actual fuel mixture burning in the engine once the mixture's been through a cat. I can't see any merit in moving the pre-cat sensors, TBH.
Kevin
Hmmm, am presumeing the pre cats are having little or no effect, thinking a little more seriously about the relevent codes have not returned so clearly must be doing something, fair enough.
-
Watching this thread with interest as I have exactly the same problem with fuel trim issues on both banks, and EML on, I changed the fuel filter a few weeks ago, interestingly I do appear to get the fuel reading from the MID eg range is giving me what is states around town. I have a GS 500 maxscan which I can reset and read the codes, but last time I reset the codes the engine does not like it at all, ad sounds like a pil of poo for a little while until it then eventually settles down, some folks may recall this from the Newent meet. May reset them again today and see what happens, and let you know.
Hi Mike,
What engine size do you have?
When you say you're getting the same codes, do you mean that you get 0170 & 0173 together?
I don't fully understand some parts of your post there. When you say that "interestingly I do appear to get the fuel reading from the MID eg range is giving me what is states around town." I'm unsure.
Could you clarify this bit for me please?
I'll be changing my fuel filter today, assuming they have one on the shelf at the Vx stealers of course, and clearing the codes.
Exactly the same codes, read them off again tonight and reset them, restarted engine bit rough, but was OK after a minute or so, not as bad as at Newent, remember since then have done the coil packs, spark plugs and fuel filter.
Anyway, I have a 2.6, as I clock my mileage today (as I claim it back), turns out my MID reading was not giving me the same as the mileometer;
Range first thing this morning was 97 miles, done 2.1 miles and range was at 92 (bear in mind car not warmed up at that point), subsequently done a further 10 miles later today and MID went down to 72 from 92 (bear in mind I do not always drive normally). Then I reset the mpg etc., after doing less than 2 miles range at finish was 61 m/gal was showing 23.3.
I have just reset the EML will keep an eye on consumption etc tomorrow and dive normally. :y
-
Ok, filter changed and codes cleared.
I drove it like a nutter for an extra long detour home of about 8 miles altogether. No codes recurring just yet, but I won't trust it until I've driven it a bit further.
I don't know if it's my imagination, but the car seemed about 20% more powerful today after the filter was changed. I booted it when I was driving at 30mph in the wet and the back wheels just kept spinning and jumping on and off the TC for about 200yds. It was great fun. The car seems to launch much more than it did.
As I said I have to drive to Gateshead this week so that is a good test. I fully suspect that I will get 0420 and 0430 again, but that doesn't bother me. If anything it is good because I am currently back where I started with regard to sensor positions etc. What I really want is not to get the 0170 and 0173 again.
I had a damn good look at all the various air pipes etc. and with the exception of the one which dissapears under the plenum, because I can't see it, and as far as I can make out all are confirmed as fine at the moment.
As for the suggestion to move the 1st sensors to behind the pre-cats, I agree with Kevin, there is very little point as it won't prove anything and won't reflect what a 3.0 cat section would be like anyway.
My intended sequence of next steps are:
- Carry on for now until I can confirm either way whether the 0170 and 0173 are fixed.
- Act further on 0170 and 0173 if necessary until fixed.
- Move secondary sensors to behind the main cats again and drive for a test period of 2 weeks or 500 miles whichever is sooner. This will test the 0420 and 0430.
- Then finally check out the resistance of the pre-cat to see if it is worth moving to a stainless steel set up with sports cats in the place of main cats only.
-
I couldn't wait in all evening and not try, so I just went for a "pushing it" drive for 25 miles each way up the A1 and back.
No codes, not even an 0420 or 0430 as yet. :y
Considering that I got the 0173 and 0170 come up within 3 or 4 miles every time I had them cleared lately this is certainly an massive improvement so far.
I'll still stick to the plan.
-
Fingers crossed. Sounds like you need something that can look at the fuel trims live? That would be the best way to confirm it one way or the other although it doesn't take long for the fuel trims to settle. More power is an indication it was being starved of fuel before.
Kevin
-
Bugger! >:(
0170 & 0173 on the way to work this morning. It's only a 4 mile journey and the EML light came on about half way there. After I pulled into the car park I switched the ignition off and then on again for the pedal trick...0170 and 0173 only.
I reckon this could be a combination of things. The fuel filter definitely made a difference.
What do you reckon next? :-/
-
Bugger! >:(
0170 & 0173 on the way to work this morning. It's only a 4 mile journey and the EML light came on about half way there. After I pulled into the car park I switched the ignition off and then on again for the pedal trick...0170 and 0173 only.
I reckon this could be a combination of things. The fuel filter definitely made a difference.
What do you reckon next? :-/
Well I reset mine las nisght, done 12 miles today and EML still off, but normally will come back on between 40-70 miles, stays off when motorway driving untl hit town driving then would come on again, when I started the car this morning sounded like a pile of poo :-/....but did'nt take as long as before to sort itself out :-/ eg wanting to cut out.
-
My car runs sweet as a nut even straight after resetting the codes. :-/
I wish I could find out the root cause of this. Someone said to me the other day that "MAF units are always going on Omegas", but I never see anyone complain about it on here, so I don't know whether to takke that with a pinch of salt or not.
-
My car runs sweet as a nut even straight after resetting the codes. :-/
I wish I could find out the root cause of this. Someone said to me the other day that "MAF units are always going on Omegas", but I never see anyone complain about it on here, so I don't know whether to takke that with a pinch of salt or not.
Genreal opinion on here,
Maf very rarely fails.
Im sure Jamie will agree when he sees this. And you have no Maf code?
Have the simple things been eliminated? have to say fuel filter would be one of them?(sorry, a bit of a low blow) air filter plugs usual service stuff. Just thinking if the fuel filter hash made a difference, have any other service items been over looked?
-
My car runs sweet as a nut even straight after resetting the codes. :-/
I wish I could find out the root cause of this. Someone said to me the other day that "MAF units are always going on Omegas", but I never see anyone complain about it on here, so I don't know whether to takke that with a pinch of salt or not.
Genreal opinion on here,
Maf very rarely fails.
Im sure Jamie will agree when he sees this. And you have no Maf code?
Have the simple things been eliminated? have to say fuel filter would be one of them?(sorry, a bit of a low blow) air filter plugs usual service stuff. Just thinking if the fuel filter hash made a difference, have any other service items been over looked?
Fair question. I can't remember if I have missed something from this list:
- air filter
- plugs
- oil
- oil filter
- HT Leads
- plugs
- breathers cleaned thoroughly
- cam-cover gaskets
- plunum 'O' rings
- water pump
- timing belt
- coolant
All changed recently. Most of the big (timing belt related) stuff was done by JamesV6CDX.
-
http://www.obd-codes.com/trouble_codes/
The above link, which you may have seen on here before, from Entwood, gives seperate codes for lean and rich. So, are we "assumeing" your "fuel trim malfunction" is giving a rich mixture? Do your codes encompas lean and rich? Or does 0170 and 0173 mean something else. Yes the "trim" is out of limits but if its rich why is there not a rich code? or whatever.
On the Maf subject, i dont mean to be rude, but do you have a cone/oiled filter? They can oil up the maf (as you probably know tbh), is it worth cleaning the maf anyway just to eliminate it?
You will see also in the link, the site has its own forum. Might be worth a go...
And you probably mean coil packs in your list above rather than ht leads? A very minor, rather picky point...
-
Fuel trims are going positive so I assume adding fuel to correct a lean condition. The output of the MAF does appear to "flat top" on the datalog when you view the calculated volume but the raw voltage doesn't, and this doesn't co-incide with huge fuel trim. I must get a log off mine and see if it does the same.
I doubt it's ignition related as it would misfire before throwing obscure codes IME.
At the end of the day, the ECU is calculating the volume of fuel to inject but the engine needs more than it's getting, so either the inputs to the ECU are faulty or the fuel calculated by the ECU is not being injected due to a fuel system problem.
MAF is the primary input into the ECU in addition to throttle positition, temperatures, etc. Temperatures look fine on the log. Throttle position is controlled by the ECU and very carefully monitored for errors on a DBW so I doubt a problem there. There don't appear to be air leaks, and the behaviour (more trim under heavy load) suggests it's not a leak into the vacuum side which only leaves the ducting from MAF to throttle body. Nothing visibly wrong there.
I agree the MAF is a possible candidate and I'll have to get a datalog from mine and see if the readings are broadly similar.
Failing that it still points to fuel system. It's exactly the same for both banks so I think clogged injectors are unlikely. Could be a poor fuel pump (might explain why a filter change helped a little). :-/ Could be the fuel pressure regulator I guess. :-/
I keep coming back to the fact that it happened when the exhaust was changed, I must admit.
Kevin
-
Is the vac pipe to the fuel pressure regulator on and ok?
-
Is the vac pipe to the fuel pressure regulator on and ok?
Front end of it certainly is. Might well be worth lifting the plenum and checking the back end.
Kevin
-
Is the vac pipe to the fuel pressure regulator on and ok?
Front end of it certainly is. Might well be worth lifting the plenum and checking the back end.
Kevin
I'll have to have a look to make sure when I get back from Newcastle. I suspect it will be this weekend. I won't need to replace any of the 'O' Rings etc will I as these were done when the cam-belt was done recently.
-
http://www.obd-codes.com/trouble_codes/
The above link, which you may have seen on here before, from Entwood, gives seperate codes for lean and rich. So, are we "assumeing" your "fuel trim malfunction" is giving a rich mixture? Do your codes encompas lean and rich? Or does 0170 and 0173 mean something else. Yes the "trim" is out of limits but if its rich why is there not a rich code? or whatever.
On the Maf subject, i dont mean to be rude, but do you have a cone/oiled filter? They can oil up the maf (as you probably know tbh), is it worth cleaning the maf anyway just to eliminate it?
You will see also in the link, the site has its own forum. Might be worth a go...
And you probably mean coil packs in your list above rather than ht leads? A very minor, rather picky point...
No cone filter, just a new standard air filter. I think cone filters are $hite because they draw warm air (Put an oiled sports panel filter in if you must). Yes I do mean coil packs and they weren't changed; I just got away with myself a bit on the list.
As for :http://www.obd-codes.com/trouble_codes/
P0170 Fuel Trim Malfunction (Bank 1)
P0173 Fuel Trim Malfunction (Bank 2)
Come up simultaneously and Kevin has answered most of your questions above^^
Thanks for all your thoughts and input though, they are appreciated and will only add value. :y
-
in relation to the exhaust on your car, iirc Steve (sp32) has the same system/car/age/mileage ish? And presumably does not have any issues?
Has he had the cat codes/lambdas moved.
Is it safe to assume his car is set up the same and does not have the fuel trim issue? Mark dtm plugged in tech2 to his car at the rolling road day but i cant remember the outcome...
-
Daft question .. from one who knows nowt.. and is struggling to follow kevins excellent arguments .. .. but ...
Is the fuel trim actually doing/achieving anything ??? .. I mean the code is a trim malfunction, not an overfuel or underfuel ?? Is the "system" sending a small signal to fuel trim that does not happen, so a bigger one is sent, then another bigger one etc etc until the limit is reached and the light comes on ??
I'm guessing that fuel trim is "achieved" by varying the injector open timing, or is there something else
Kevin wrote
Fuel trims are going positive so I assume adding fuel to correct a lean condition
I'm wondering if the fuel trim read is an increasing voltage TRYING to add fuel but failing to do so ???
Tell me to shut up if I'm making no sense ... :(
-
Fuel trim is a correction added to the fuel value that is calculated by the ECU, based on the corrrection it has had to apply to keep the Lambda sensors happy.
Essentially, the ECU calculates the amount of fuel it should be injecting based on the engine operating conditions and this determines the injector duration. Feedback from the Lambda sensors tell it this is too lean, so it adds "fuel trim" (lenghtening the injector duration) until the Lambda sensors are reading a little rich, then backs it off a little, and so the cycle repeats.
All that has happened in this case is that the fuel trim value has exceeded a reasonable value. 24% looking at the data from Albatross' car.
This is normally indicative of some sort of fault, but of course the fault can be in the metering of the engine operating conditions - temperatures, MAF, etc. It can be due to unmetered air entering the induction system, misreading Lambda sensors due to an exhaust leak, and it can also be because the fuel system is not delivering the correct flow rate through the injectors for some reason - weak fuel pump, clogged filter / injectors, incorrect fuel pressure. A poorly mapped LPG system will do it too.
So, to answer your question, yes. The fuel trim is achieving something. It is keeping the air fuel ratio correct, but it is having to apply a suspiciously high correction to do so, and that's what the fault code is telling us.
Kevin
-
.. or to put it in aviation terms, the trim is fully back, but you're still having to pull on the stick to stop the nose dropping, so something is not right. :-?
Kevin
-
so, as you (Kevin) where saying about the exhaust, if it is more free flowing, fuel trim would increase to get the mixture correct again...?
-
.. or to put it in aviation terms, the trim is fully back, but you're still having to pull on the stick to stop the nose dropping, so something is not right. :-?
Kevin
Love that analogy .. one I understand !!
Taking it on then .. what if the trim indicator SAYS the trim is fully back but the trim tab hasn't actually moved.. you now have to move the stick more than expected ...... (equiv to fuel trim saying to injectors change opening times but they don't ?? )
I'll guess your answer will be that as the lambda readings are in limits then the fuel trim must be working (analogy: .. stick loading reduces as indicator moves but still remains excessive which confirms trim tab has moved therefore trim tab system functioning)
:)
-
in relation to the exhaust on your car, iirc Steve (sp32) has the same system/car/age/mileage ish? And presumably does not have any issues?
Has he had the cat codes/lambdas moved.
Is it safe to assume his car is set up the same and does not have the fuel trim issue? Mark dtm plugged in tech2 to his car at the rolling road day but i cant remember the outcome...
For what it worth, i pm'd Steve (SP.32) re his exhaust, and he only has the back box. Not the full cat back system as Albatross has.
So that wont be a fair comparison. I wonder if Albatross has the middle boxs on his exhaust or is it straight through to the rear silencer? Would that then run more freely and need more fuel to balance the mixture?
-
so, as you (Kevin) where saying about the exhaust, if it is more free flowing, fuel trim would increase to get the mixture correct again...?
Well, not in an ideal world. :-/ In theory the MAF measures all the air that gets into the engine, so the ECU knows how much air is going in and knows how much fuel to add. A freer exhaust would result in more air, but the ECU would know about it so it shoudn't be corrected by fuel trim. It shouldn't have an effect on fuel trim but the fact remains that the fuel trim problem co-incided with the exhaust change.
EDIT: Abatross' exhaust does have a centre box (although I think just a single large box raher than two boxes?). It looked about as close to a standard system as you could get, TBH
Kevin
-
so, as you (Kevin) where saying about the exhaust, if it is more free flowing, fuel trim would increase to get the mixture correct again...?
Well, not in an ideal world. :-/ In theory the MAF measures all the air that gets into the engine, so the ECU knows how much air is going in and knows how much fuel to add. A freer exhaust would result in more air, but the ECU would know about it so it shoudn't be corrected by fuel trim. It shouldn't have an effect on fuel trim but the fact remains that the fuel trim problem co-incided with the exhaust change.
EDIT: Abatross' exhaust does have a centre box (although I think just a single large box rather than two boxes?). It looked about as close to a standard system as you could get, TBH
Kevin
I've been offline at a customer site for much of this week so have missed out on these debates. Very interesting too.
As Kevin says, my exhaust has a pretty standard set up. The "single large box" that Kevin refers to is a single box with two seperate segments one for each bank. It is a 2 in 2 out box. The 2 banks' exhaust flows never actually meet as both through the centre box and the back box the pipes (flows) are through their own discrete flows.
I'm a bit stuck now, as I don't know what to look out for next. All air pipes are good.
If I want to get the fuel pressure checked, what do I need to do? Should a good mechanic / garage know what to do? What should the pressure be?
-
I've just had a long chat with a chap from a specialist garage that deals with this sort of thing here in Bedford.
He says that he thinks:
- It is unlikely to be a fuel pressure issue
- More likely a MAF issue
- The exhaust change will not be a cause
- The secondary sensors definitley do NOT affect trim, but only measure the pre-cat efficiency.
As far as he is concerned I need to bring the car down to him and leave it with him for the day to scan it. He wants to check the MAF sensor voltage and the grams per hour rate of the air flow too.
He's quoted me £50 for the initial scanning etc.
I had another chat with a mobile engine tuning chap and the first thing he said was have you checked the fuel pressure?
Any thoughts? (Kevin et al.)
Do you think that it is worthwhile to start to go down the road of investing in the 1st garage's time and investigations?
-
another maf refrance. I would try cleaning the maf first. Then if it persists see your man.
Give maf a good spray with carb cleaner. Easy job. Dont physicaly touch the internals with anything solid. Like a brush, rag or finger. Good chance itll break.
-
Is the MAF the big metal block that bolts onto the front of the plenum?
If so I cleaned out the "MAF block" when I did the breathers whilst JamesV6CDX was doing the cam-belt and water pump.
I did touch stuff, but only with carb-cleaner, fingers and kitchen roll. I'm pretty sure I didn't break anything.
The breather, plenum and that metal block with the butterfly valves were like new when I (James) put it all back together.
-
no thats the throttle body. Maf is up stream of there. Iirc, look at air box. The maf i think is next in line. Its black plastic with electrical plug.
Ps, might be worth checking all the jubilee clips are tight on the air intakes/bag pipes. Makes sure there are no air leaks/splits cracks in the plastics.
-
But any air leaks that could possibly be related if they are there at all would be downstream of the MAF sensor wouldn't they?
Otherwise the MAF sensor would be "aware" of the additional air going through it.
-
But any air leaks that could possibly be related if they are there at all would be downstream of the MAF sensor wouldn't they?
Otherwise the MAF sensor would be "aware" of the additional air going through it.
Yep. Air leak. Proper term, unmetered air.
-
Is there a picture around of an engine bay with MAF sensor and related bits highlighted?
Even a picture of the MAF sensor itself would be useful. I've looked through the maintenance section.
-
Is there a picture around of an engine bay with MAF sensor and related bits highlighted?
Even a picture of the MAF sensor itself would be useful. I've looked through the maintenance section.
MAF sensor is just below the elbow that leads from the lid of the air cleaner box. Yours is reading exactly the same as mine at idle. Not so sure further up the rev range but might eb worth a try giving it a clean. If that doesn't work, investigate the fuel system a bit further I reckon.
Kevin
-
Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?
Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?
-
Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?
Well, they both have hunches based on what they've seen before. The question is: will either of them go through a logical sequence of eliminating the possibilities or will they start replacing expensive parts based on hunches?
Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?
They both have identified possible issues which need to be investigated. We know MAF failures are rare on an Omega, and I've looked through your datalog again tonight side by side with a log from my car and I reckon the MAF signal looks OK. I might be wrong because I haven't compared logs from the same route, speed, driver, etc. but it's certainly not dead.
I think my money is still on something in the fuel supply - low pressure or poor delivery from the pump.
Keivn
-
(http://i344.photobucket.com/albums/p326/chrisgixer/15112008275.jpg)
hop helps ;)
-
Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?
Well, they both have hunches based on what they've seen before. The question is: will either of them go through a logical sequence of eliminating the possibilities or will they start replacing expensive parts based on hunches?
Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?
They both have identified possible issues which need to be investigated. We know MAF failures are rare on an Omega, and I've looked through your datalog again tonight side by side with a log from my car and I reckon the MAF signal looks OK. I might be wrong because I haven't compared logs from the same route, speed, driver, etc. but it's certainly not dead.
I think my money is still on something in the fuel supply - low pressure or poor delivery from the pump.
Kevin
Thanks as ever...
Is the "log" you talk about something that can be posted as meaningful information? Can mine and yours be posted? I'd really like to have them to show to whoever is going to look at this.
I plan on summarising this thread and having it all ready and printed out for their benefit as I think it will help focus their investigations and save me a little money. It will also help me to look a little less clueless and be able to hold my ground on the process and not let them take the mickey.
(http://i344.photobucket.com/albums/p326/chrisgixer/15112008275.jpg)
hope helps ;)
A lot, thanks also Chris :y
-
Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173. ::)
No obvious air leaks anywhere but fuel trim up to 24% on both banks.
To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.
Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.
Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?
Kevin
-
Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173. ::)
No obvious air leaks anywhere but fuel trim up to 24% on both banks.
To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.
Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.
Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?
Kevin
That is a very, very interesting development. Thanks Kevin.
I can get my car to a reader, but they're going to charge me £50 for the privelige!
Now I know this, I am probably going to see when TB is about to nip over to Brackley for a quick read.
Where can I get the "security bit" you refer to? Do you think that it is worthwhile doing this cleaning of the element?
How much is a new MAF sensor? I may just bugger it and buy / fit a new one as I could spend as much diagnosing as fixing here.
I'm tempted to buy a new MAF sensor tomorrow 1st thing, fit it, get the codes cleared, get the secondary O2 sensors moved back to behind the main cats and drive it to Leicestershire this week to see what happens.
-
Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173. ::)
No obvious air leaks anywhere but fuel trim up to 24% on both banks.
To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.
Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.
Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?
Kevin
That is a very, very interesting development. Thanks Kevin.
I can get my car to a reader, but they're going to charge me £50 for the privelige!
Now I know this, I am probably going to see when TB is about to nip over to Brackley for a quick read.
Where can I get the "security bit" you refer to? Do you think that it is worthwhile doing this cleaning of the element?
How much is a new MAF sensor? I may just bugger it and buy / fit a new one as I could spend as much diagnosing as fixing here.
I'm tempted to buy a new MAF sensor tomorrow 1st thing, fit it, get the codes cleared, get the secondary O2 sensors moved back to behind the main cats and drive it to Leicestershire this week to see what happens.
iirc the "securaty bits" are torx bits with a hole in the end to get the air box/cleaner lid off etc, Halfords at a guess? Worth a clean first, Mafs aint cheap. :'(
-
Either that or I could buy a new MAF sensor, go to TB, get the readings of kg/h at high idle (2400 rpm). If it is "faulty" then swap it clear the codes and retest. Should be good to go.
If not, then I can return the MAF sensor and get my money back, nothing lost.
If the MAF sensor is faulty I'll need a new one soon enough I reckon don't you?
-
Either that or I could buy a new MAF sensor, go to TB, get the readings of kg/h at high idle (2400 rpm). If it is "faulty" then swap it clear the codes and retest. Should be good to go.
If not, then I can return the MAF sensor and get my money back, nothing lost.
If the MAF sensor is faulty I'll need a new one soon enough I reckon don't you?
Go on ,get your hands dirty ;)
-
Just to let you know that last saturday I had my EML come on after filling her up with Tescos 99 RON rocket fuel and doing a 180 mile run non stop immediately after filling up.
Got the 0170 and 0173 codes,after a 2 hr stop but the car continued running perfectly and whilst having the light cleared by Mark we found the codes had cleared themselves.
Running on Shell now and wont be using Tescos again.
:)
-
I have been known to use Tesco 99RON fuel a few times.
Do you reckon that it could have damaged (clogged up) the MAF sensor?
I always run on the Super Unleaded fuel and tend to use BP when I can.
EDIT: That was a really dumb question. Fuel can't clog an air sensor can it. Dolt!
-
I just called my Vx stealers this morning and they have offered me one for £130 rather than the full retail of £180.
This rate is because they know me and always give me TC price discount rates on whatever I buy whether it is listed or not.
I'm just going to buy a new one out of frustration and to KNOW that it is fixed. It will be on my car by 2pm and the O2 sensors will be back behind the main cats as before.
I am doing this on the strength of the diagnostics work that Kevin did to Keiran's car this weekend.
I'll be driving to Leicestershire for a couple of days, so that should prove this one way or another. If it doesn't I wonder if I can take the MAF back as "unused"?
-
See Kieran's thread. I can pop an ELM reader in the post if you want to double check before shelling out for a MAF.
Normally, stealers won't take back electrical items, IIRC. :-/
Kevin
-
http://www.omegaowners.com/forum/YaBB.pl?num=1226911441/15#22
Having just received a very welcome PM from Kieran, I have just ordered a MAF sensor for £33.50 which will be here this week.
That's £100 off what I thought was a good deal and £150 less than the retail price from Vx.
No bl00dy wonder they're called "stealers".
Thanks Kieran and Olympia what a STAR! :y
-
I have been known to use Tesco 99RON fuel a few times. Do you reckon that it could have damaged (clogged up) the MAF sensor?
I always run on the Super Unleaded fuel and tend to use BP when I can.
EDIT: That was a really dumb question. Fuel can't clog an air sensor can it. Dolt!
lol
I know what i posted was not really that relevant to this highly technical thread, just wanted to point out that I had this problem and it was something totally different to what is being discussed here.
Cheers
Martyn
:)
-
http://www.omegaowners.com/forum/YaBB.pl?num=1226911441/15#22
Having just received a very welcome PM from Kieran, I have just ordered a MAF sensor for £33.50 which will be here this week.
That's £100 off what I thought was a good deal and £150 less than the retail price from Vx.
No bl00dy wonder they're called "stealers".
Thanks Kieran and Olympia what a STAR! :y
This seemed like such a good idea at the time, but despite reassurances that this would be sent so that it would be with me by recorded delivery on Thursday before 1pm, I still haven't seen hide nor hair of it.
I'm beginning to wish I'd just spent the extra money and had it done and dusted on Monday.
False economy? Perhaps not just yet considering the saving, but I'm not best pleased. If it isn't here ON Monday morning I'm canceling, expecting a refund and off down to the stealers.
-
Very interesting been watching this thread with interes, as I reset my codes but after a few days EML came back on again, so if changing the MAF works, then the samejust might solve my problem, will wait for the results :y
-
Right the MAF sensor arrived today and I fitted it this evening.
The car started, then died again.
The car started, then died again.
The car started, then died again.
The car started, then died again.
The car started, then died again.
The car started, then died again.
The car started, splutttered, then died again.
The car started, splutttered, then died again.
The car started, splutttered, then died again.
The car started, splutttered, then died again.
The car started, splutttered, then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then suddenly the engine raced like crazy when I hit the pedal and covered my nice white garage door in black soot then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then suddenly the engine raced like crazy when I hit the pedal and covered my nice white garage door in black soot then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then suddenly the engine raced like crazy when I hit the pedal and covered my nice white garage door in black soot then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then suddenly the engine raced like crazy when I hit the pedal and covered my nice white garage door in black soot then died again.
The car started, splutttered, then stayed running, wouldn't react when I pressed the pedal at all, then suddenly the engine raced like crazy when I hit the pedal and covered my nice white garage door in black soot then managed to stay going.
I took it out for a run for about 50 miles and BL00DY HELL! it is like a different car. The pedal is so much more reactive than it was and you could almost feel it stutter before it went. By the latter half of the run it settled down and really began to run much better; it actually gives you a forceable shove in the kidneys when you floor it from 100.
I'll be down to clear the EML light tomorrow morning and keep you posted.
If that stays clear for a week then I'll revert the secondary lambda sensors to behind the main cats.
If that then keeps the dreaded 0420 & 0430 away after a couple of weeks I'm considering a set of standard 3.0 front pipes to remove the pre-cats altogether.
-
22 re starts, blimey! Presume its learning? I take it The car now ticks over as it should? And now goes like snot by the sound of it?
-
22 re starts, blimey! Presume its learning? I take it The car now ticks over as it should? And now goes like snot by the sound of it?
It's a bit of a slow learner, but it's good at PE ;D
-
Keep is posted, as if the 0170-0173 codes stay away then a new MAF maybe the answer to my EML aswell as Bob.dent aswell, as he has the same problem (or at least I think he still does)................
Interesting about the learning bit, as if I reset the codes again, the car takes a bit of time to run normal, but a lot quicker than at Newent, probabaly cause all new sparks and DIS packs though :-X
-
Keep is posted, as if the 0170-0173 codes stay away then a new MAF maybe the answer to my EML as well as Bob.dent as well, as he has the same problem (or at least I think he still does)................
Interesting about the learning bit, as if I reset the codes again, the car takes a bit of time to run normal, but a lot quicker than at Newent, probably cause all new sparks and DIS packs though :-X
Ironically enough and unlike yours, resetting the DTC codes on mine made virtually no difference to how the engine ran in the very short term.
The car has always run sweet as a nut. I was getting the 0420 & 0430 which was the "tired pre-cat" message.
I moved the secondary sensors back to behind the main cats.
At around about the same time (entirely co-incidence, I am now led to believe) I started getting the 0170 & 0173.
But throughout this time the engine has run smoothly until last night.
Let's see how it copes with me and my right foot today. :y
-
Sounds like a result to me. :y
It would have built up a large fuel trim hence the chronic over fuelling when you started it with the correct signal from the MAF.
For future reference if you need to change a MAF that's built up a large fuel trim you can reset the trim by clearing the codes (e.g. with a cheapo Tech 2) or, warm up the car on the old MAF so the Lambda sensors are active and change the MAF while it's hot.
Hopefully we are near the end of a long, frustrating road. :y
Kevin
-
I drove about 2 miles to the petrol station this morning, stopped, filled up, paid and then as I started her up again the EML light had cleared itself.
Result! Must have been the MAF sensor.
As this happened I have greater confidence in the root cause and have moved the secondary O2 sensors back to behind the main cats again.
Still no EML light despite a 20-30 mile drive since.
Touch wood, this could be the end of this thread.
-
Confirmed as another MAF sensor issue.
Replaced MAF and problem solved :y
Ironically enough, right at the outset my local garage said to me "check the MAF sensor, it's common"
Having asked on here the response was largely "Unlikely".
Recently I have noticed that there has been quite a little spate of these, so well worth getting it checked out. For £33.50 for a new one incl P&P & excellent service (see above for contact details) you can't argue really and my car is a different machine with no EML.
Thread finally dead and buried.
Thanks Kevin, Jaime and Chris for your help. :y
-
Excellent news. Glad its sorted. :-)
-
I had the same codes a year ago, local Opel shop could not find the fault but the mechanic said he had once searched for the reason on a vectra with 2,6 engine for several days and the result was MAF. However, when I changed mine, I had the same codes twice within two weeks from the change and since then have not had the codes.
-
It makes me wonder if the MAFs on DBW cars don't have the same legendary reliability. :-/
Kevin
-
It makes me wonder if the MAFs on DBW cars don't have the same legendary reliability. :-/
Kevin
At 33.50 per MAF and at least I know what the problem is likely to be then I'll live with that though.
There is no sign of the 0420 & 0430 either so I think the moving back of the O2 sensors has worked.
Do you think I'd gain anything by putting standard 3.0 front sections on now and completely removing the pre-cats? There must be some resistance / back-pressure caused by them.
-
It makes me wonder if the MAFs on DBW cars don't have the same legendary reliability. :-/
Kevin
At 33.50 per MAF and at least I know what the problem is likely to be then I'll live with that though.
There is no sign of the 0420 & 0430 either so I think the moving back of the O2 sensors has worked.
Do you think I'd gain anything by putting standard 3.0 front sections on now and completely removing the pre-cats? There must be some resistance / back-pressure caused by them.
Not sure, TBH. :-/ There might be some benefit. On the other hand, the single cat on the 3.0 might be more dense to compensate.
Kevin
-
Mmmm i might invest in one of these to see if it clears my problem 0420 code too . :y
-
Mmmm i might invest in one of these to see if it clears my problem 0420 code too . :y
0420 is unlikely to be the MAF, I'd say. That's a cat efficiency code so relocation of the cat check Lambda sensor would be the best bet, IMHO.
Kevin
-
Mmmm i might invest in one of these to see if it clears my problem 0420 code too . :y
Kev's bang on; read my last post on your "0420" post.
BTW, once you have fixed it by moving the O2 sensor back, I did notice that you're running an 11% long term fuel trim. For that reason only I might consider the MAF, but Kevin will know better than me. It is a lot less than mine was at 24% though. (EML code 0170 was coming up)
-
Mmmm i might invest in one of these to see if it clears my problem 0420 code too . :y
Kev's bang on; read my last post on your "0420" post.
BTW, once you have fixed it by moving the O2 sensor back, I did notice that you're running an 11% long term fuel trim. For that reason only I might consider the MAF, but Kevin will know better than me. It is a lot less than mine was at 24% though. (EML code 0170 was coming up)
A bit of diagnostics with a Tech 2 is required really. 11% fuel trim is on the high side, and 2.2s don't appear to suffer from 0420 codes generally. IIRC, a new cat has been fitted to this car to no avail so maybe something else is going on. :-/
Kevin
-
Hi all! I am new here and just found this thread. I have similar problems with my 3.2 engine (error codes P0170 & P0173).
I've checked for vacuum leaks but haven't found any, and I've just changed the plugs and the MAF. I've been logging the engine data, and it seems that when I lift the throttle pedal, the short term fuel trims shoots up to +25% (you can see that between 20 and 38 seconds on the graph). Otherwise it looks quite ok for me.
Can anyone advice what to check next? I think I will try to clean the throttle body and butterfly.
(http://i35.tinypic.com/119vxhf.jpg)
-
Lots of fuel trim on a closed or light throttle points to an air leak into the plenum after the throttle body - when vacuum is greatest on a light throttle. I'd check the breather pipes and plastic breather box on the plenum are air tight, the plenum-to-inlet manifold seals and also the vacuum pipe to the brake servo.
Kevin
-
Should have said... During the area where the problem occurs on that graph, was the throttle totally closed or just lightly applied?
It's showing a few percent throttle and a few percent load, that's all. :-/
Will have to see what mine reports under similar conditions.
Kevin
-
Thanks for reply Kevin.
I had lifted my foot from throttle, but my car has autobox and this time the engine was not braking either. Do you have any tips how to check the pipes, seals and the breather box vacuum "bulletproof"?
-
Ahh, OK. Of course, it's throttle position, not necessarily pedal position.
I might start by measuring the vacuum at the "T" piece by the brake servo. Use a gunsons "Low gauge" or similar. 18-20 In.Hg would be a typical reading at idle when warm. Any less and it might indicate a vacuum leak somewhere.
Kevin
-
Hi!
The codes are still on. Now I have had a smoke test for vacuum leaks, and according to the mechanic my car has no vacuum leaks at all. He also tested the lambdas and they were ok. When cruising downhill and the pedal is up and throttle is light, both STFT's rockets up to 25. Here is some recent data:
(http://i50.tinypic.com/eitmpz.jpg)
Anyone got ideas how to proceed? Could this be caused by faulty ignition coils?
-
No, coil packs won't bother it.
Usual issue with fuel trim codes is maf, swap yours for a known good one and see if it behaves to diagnose. If faulty search the Bosch part number on the maf itself, it fits numerous vehicles including the 2.6.
-
Totally agree, my 2.6 showed 0170 and 0173 and maf sourced off ebay for £22 quid (sensor only)
:y
-
Thanks, I've already changed the maf for a brand new OEM Bosch part (same part number) from vauxhallworldparts.co.uk
In the most cases I've seen, the long term fuel trim values are high if the maf is faulty. In my case, the LTFT values are low but short term trims are equally high.
I'm starting to doubt the smoke test, is it bulletproof way to check the vacuum leaks?
-
Thanks, I've already changed the maf for a brand new OEM Bosch part (same part number) from vauxhallworldparts.co.uk
In the most cases I've seen, the long term fuel trim values are high if the maf is faulty. In my case, the LTFT values are low but short term trims are equally high.
I'm starting to doubt the smoke test, is it bulletproof way to check the vacuum leaks?
Never heard of it. A pudding pull IMO.
-
Where are you in the world? Roughly?
-
Well, I assume the smoke tester is something like this: http://www.youtube.com/watch?v=FfiQ7qWiG-M
I wasn't watching the test in the shop, but it was Bosch car service...
-
Load of 'dangle berries'. Intake is negative pressure times a lot more than the positive pressure supplied there. Not a definitive test by a long way ;D
-
Considering what happens with light versus full throttle for a minute:
Light throttle : Vacuum in the intake system post-throttle is high, as the engine is sucking against a closed throttle. Airflow is low. Very little vacuum in system up to the throttle due to low airflow through MAF, air filter, ducting, etc.
Full Throttle : Slight (much lower) vacuum in the whole intake system from air box to intake valve due to high rate of airflow.
What we are seeing is high positive fuel trim in the Light throttle scenario and normal trim under heavier throttle. Positive fuel trim means fuel is being added ergo there is more air getting into the engine than the MAF is reporting. This means an air leak.
As it is not happening under heavier load, we can infer that it's the part that's under vacuum at the time that's causing the problem, i.e. the intake system after the throttle so plenum and manifold seals, Vacuum supply to brake servo and multirams, bung where the ICV connects to the plenum, breather bridge seal, etc.
I wouldn't put a lot of faith in a smoke test either. Better to give the above a thorough inspection for damage. Maybe go round using a length of hose to the ear as a stethoscope or spray some carb cleaner over the areas concerned and see if it upsets the idle.
Also worth putting a vacuum gauge on the T piece by the brake servo to check the vacuum at idle. 18-20in Hg / 30 kPa would be about right. If it's less it might confirm the suspicions of a leak.
Kevin
-
Much appreciated the clear explanation Kevin!
I just ordered the Gunsons G4103 LoGauge vacuum meter from ebay, so I'll try to find the possible leak myself. It looks like the leak should be equal to both sides of V (from the equal STFT1&2 trim values).
-
Much appreciated the clear explanation Kevin!
I just ordered the Gunsons G4103 LoGauge vacuum meter from ebay, so I'll try to find the possible leak myself. It looks like the leak should be equal to both sides of V (from the equal STFT1&2 trim values).
Yep, another good point, so something common to both banks.
Kevin
-
Finally got the Gunson meter, here are the idle results, taken directly from the vacuum line from intake system:
(http://i37.tinypic.com/2hn28o6.jpg)
That doesn't look too bad?
-
Just wanted to feedback the happy ending: There was a small vacuum leak in one of the vacuum tubes. After fixing this leak by replacing the tube, there has not been any error codes.
-
And the fuel trims?
-
And the fuel trims?
Haven't bother to check the values, I assume they are within specs because there hasn't been error codes anymore. If you want to know some values I can connect my laptop and check..