Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: tommy mac on 19 March 2013, 17:30:15
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Hi everyone,
I'm new to the group but have been exploring the site in some detail as an owner of a 52 plate 2.2cd auto. The car has recently covered 100,000 miles and a few weeks ago James (The Omegamechanic :y) fitted a new cambelt and gear selector switch for me. What a find James is, and such a knowledgeable chap!
Last week the car failed its MOT on the emissions and the garage identified the problem as the lambda sensor (the error code P0107 kept appearing). I changed the sensor and the error code went away but the car has not been running well. On a long run it was clear that acceleration was fine but there was a noticeable hesitancy when cruising at a steady speed. James pointed out that the cam cover was leaking (oil in the plug wells) so I decided to change the gasket and clean all the breather pipes. I did this and aqalso removed and cleaned the throttle valve assembly, replacing it with a new gasket. After this the car started very well indeed but had a hint of rough running when idling. A short drive was not reassuring as the car accelerated well but is even more hesitant than before and struggling to run at a steady speed. A check of the error codes showed only one that related to not enough torque from the engine. After another check to ensure I had not missed any poor connections or loose pipes I started the engine again and despite an easy start it seems to be running rougher than ever. Going through all the posts of similar issues on here isn't helping me with this problem. I have checked and double checked the electrical connections, and made sure all the pipes are connected properly but the problem seems to be getting worse.
My thoughts are that the fact it is starting well suggests that the ignition system is probably ok, and based on anexperience with a previous car (30 years ago!) the symptoms could suggest fuel starvation. Could it be linked to the MOT emissions failure - could it be the mass air flow meter?
I am so aware of how easy it is to chase my own tail when tracking down the cause of such problems so any ideas would be of help.
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Are the long term trims around 0% (assuming your code reader can read it)?
Any stored codes?
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Sorry I can't read the trims on my reader and there are no stored codes......the P0107 was the only code that has come up (other than the recent low torque message which I assume was due to the power issue giving the gearbox a problem) and that vanished with the new lamda sensor.
Tom
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If you can get to Wootton Bassett tomorrow I should be able to read the trims for you ??
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If you can get to Wootton Bassett tomorrow I should be able to read the trims for you ??
If you 2 can get together, can you get:
Codes
Trims
MAF
Confirm that S1 flicks at about 1hz, S2 is always lean
Might be worth checking condition of coil pack - easy on 4 pot, slide the trim back, unplug CP at rear, unbolt and lift as per a V6 one.
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If you can get to Wootton Bassett tomorrow I should be able to read the trims for you ??
If you 2 can get together, can you get:
Codes
Trims
MAF
Confirm that S1 flicks at about 1hz, S2 is always lean
Might be worth checking condition of coil pack - easy on 4 pot, slide the trim back, unplug CP at rear, unbolt and lift as per a V6 one.
Thats my guess ;)
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I had O2 sensor codes, but problem was MAF sensor. Disconnect MAF, if car runs better, it is bad. Very often computer doesn't recognize bad MAF sensor, because signal is within specs.
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did you change the right lambda sensor ?
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Wow- such fast responses. Thanks to all. Going in reverse order The lambda sensor changed was the front one and it certainly got rid of the error code. Whether it was the correct one I can't answer. I did try running the car with the MAF sensor disconnected with no better results and probably slightly worse. The coil pack did have oil coating the plug connectors and these have been cleaned thoroughly. I am aware that they can fail after an oil 'bath' - the low power and unsteady running could indicate an ignition problem but i don't hear any hint of misfiring. Oh to have a spare car to swap parts with.
Entwood, I can attempt a trip to Royal Wootton Bassett - is anytime in particular good for you? In the meantime I'm going over the engine with fresh pair of eyes to be doubly sure I have not done something stupid in my cleaning!
Tom
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Wow- such fast responses. Thanks to all. Going in reverse order The lambda sensor changed was the front one and it certainly got rid of the error code. Whether it was the correct one I can't answer. I did try running the car with the MAF sensor disconnected with no better results and probably slightly worse. The coil pack did have oil coating the plug connectors and these have been cleaned thoroughly. I am aware that they can fail after an oil 'bath' - the low power and unsteady running could indicate an ignition problem but i don't hear any hint of misfiring. Oh to have a spare car to swap parts with.
Entwood, I can attempt a trip to Royal Wootton Bassett - is anytime in particular good for you? In the meantime I'm going over the engine with fresh pair of eyes to be doubly sure I have not done something stupid in my cleaning!
Tom
PM sent with phone number .. :)
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I had O2 sensor codes, but problem was MAF sensor. Disconnect MAF, if car runs better, it is bad. Very often computer doesn't recognize bad MAF sensor, because signal is within specs.
Reading codes alone is a poor way to do diagnosis, hence in this case the request for live data.
Disconnecting MAF can help in diagnostics if no other tools available, but that still cannot pin it down to MAF (in cases where MAF is correct, but other sensors are incorrect)
Hope that makes sense? :)
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Quick and dirty, accurate stuff to follow...
S1 not changing,
Sht trim 0.0 not changing
Lng trim 11.7% not changing ..
Off to write some info down .. back shortly :)
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Right accurate info :)
Closed Loop
SHRTFT1 - 0.0% - not changing
LONGFT1 - 11.7% - not changing
RPM - 762
ADV - 4-6 degrees, varying slowly
MAF 2.53 g/s
TP 3.1%
O2B1S1 0.075 STATIC over 5 minutes
O2B1S2 0.330 dropping to 0.25 over 5 minutes then static
SHRTFTB1S1 0.0
Any ideas what we can check quickly/easily ?? Looks to me like the Lambda is simply not working
:(
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Whats the coolant temperature?
Also the MAF idle value when warm
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The MAF value is about 9.1 Kg/h which is a bit low.
any sign of a vac leak, pipe not fitted on inlet, brake servo pipe ok?
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No leaks apparent, done the carb cleaner trick, nothing found. Unplugged the lambda and it gave fault code 0170 as expected. plugged back in and cleared faults. engine not running S1 voltage is 0.45 as soon as engine is running in closed loop it drops to 0.075 and stays there. No faults shown
Lambda was changed 5 days ago for MOT emissions failure. Engine was NOT rough before then but is certainly rough now. Resistance from lambda body to engine block is 20 ohms.
Open loop to closed loop takes about 2-3 minutes
Am I being daft in thinking a faulty lambda has been fitted ?? are there any checks I can do on the lambda sensor
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Car was running fine until 5 days ago when code 0170 and MOT fail for emissions so lambda 1 changed. 0170 went away but car barely passed retest on emmisions.
Tom now on his way home to put the old lambda in, and (hopefully) return so we can check the readings to see what, if anything changes. Hopefully at least we'll see the old one switching which the new one doesn't.... he'll then take the (suspect) new one back and try and change it.
Does this sound like a plan ??
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Changed the lambda sensor back to the old one and straight away it came back with the P0170 error code. I think I must becoming super sensitive to the sounds of the engine but tickover still seems a little rough. Anyway back to Nige's now to put it on his meter and see what gives.
Tom
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Next set of numbers .. from the "old" sensor ...
SHRTFT1 - 0.0
LONGFT1 - 11.7
RPM 754
ADV 6-8 degrees
MAF 2.49 - 2.59 slow cycle
TP 3.1
O2B1S1 - 0.055
O2B1S2 - 0.075
SHRTFTB1S1 - 0.0
So very little difference. Tom says the car seems to "hang" at various rpm's .. so tried stepping up through the rev range .. definite hang at 4000 rpm for about 2 secs then it accelerates through. Holding RPM at 2000 B1S1 starts to cycle VERY slowly. After holding 2000 RPM for 2 minutes the system went to OL_FAULT and the "hang" at 4000 rpm had gone , although the engine still is not smooth in any way !!!
Given that BOTH sensors fail to "cycle" I'm more and more convinced that the "new" sensor is faulty .... any ideas gratefully accepted :)
Another hypothesis .... sensor heater circuit not working ??? of the 4 wires which are the heater ones .. we can then stick a meter across and check for a voltage at least !! Heater circuit failure "should" give a fault code though I think ??
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And the coolant temperature sensor reading is.....
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MAF reading is still pretty low.
And P0170 is a fuel trim malfunction and not neccassarily an O2 sensor code.
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MAF reading is still pretty low.
And P0170 is a fuel trim malfunction and not neccassarily an O2 sensor code.
When we unplug the Lambda the P0170 comes up straight away, and the S1 is not switching on either sensor ??
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Which makes me think that the MAF is giving a low reading (which it is), the ECU is applying fuel quantity based on MAF value and hence constant lean mix......all assuming its closed loop.
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Which makes me think that the MAF is giving a low reading (which it is), the ECU is applying fuel quantity based on MAF value and hence constant lean mix......all assuming its closed loop.
But whatever the actual fuel the S1 should switch at 1hz I thought ?? However .. would unplugging the MAF achieve anything ?
Engine temp off my reader is 80 C
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OK MAF unplugged
ETC 80 C
SHRTFT1 5.5
LONGFT1 11.7
RPM 871
Adv 5 deg
O2B1S1 .250 static
SHRTFTB1S1 5.5
O2B1S2 0.370
Car & Spanner light on, no codes on MIL
Engine runs without missing and accelerates throughout the range with no hesitation at all (not tried underload however)
Could it be 2 problems ?? MAF incorrect and Lambda not switching ???
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Tom's driving home with the MAF disconnected to see the effect under load .....
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Yep- drove home with the MAF disconnected and it was almost a relief as it was certainly much smoother even if the power was clearly down.
I think I'll get my hands on a MAF sensor and see what that does....if it doesn't change anything then I have reached step 2 of being an Omega owner.............building a collection of working sensors to compare with the ones on the car ;D
It's been an interesting experience so far and it has improved my understanding of the systems no end. Any thoughts following on from Nige's data are welcomed and many thanks to those responding.
Tom
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Next set of numbers .. from the "old" sensor ...
SHRTFT1 - 0.0
LONGFT1 - 11.7
RPM 754
ADV 6-8 degrees
MAF 2.49 - 2.59 slow cycle
TP 3.1
O2B1S1 - 0.055
O2B1S2 - 0.075
SHRTFTB1S1 - 0.0
So very little difference. Tom says the car seems to "hang" at various rpm's .. so tried stepping up through the rev range .. definite hang at 4000 rpm for about 2 secs then it accelerates through. Holding RPM at 2000 B1S1 starts to cycle VERY slowly. After holding 2000 RPM for 2 minutes the system went to OL_FAULT and the "hang" at 4000 rpm had gone , although the engine still is not smooth in any way !!!
Given that BOTH sensors fail to "cycle" I'm more and more convinced that the "new" sensor is faulty .... any ideas gratefully accepted :)
Another hypothesis .... sensor heater circuit not working ??? of the 4 wires which are the heater ones .. we can then stick a meter across and check for a voltage at least !! Heater circuit failure "should" give a fault code though I think ??
Black is signal,grey is earth,both whites are heater :y
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Yep- drove home with the MAF disconnected and it was almost a relief as it was certainly much smoother even if the power was clearly down.
I think I'll get my hands on a MAF sensor and see what that does....if it doesn't change anything then I have reached step 2 of being an Omega owner.............building a collection of working sensors to compare with the ones on the car ;D
It's been an interesting experience so far and it has improved my understanding of the systems no end. Any thoughts following on from Nige's data are welcomed and many thanks to those responding.
Tom
i'd try cleaning it first with electric contact cleaner. I know people on here don't favour it but it worked for me. worth a try if you were going to swap it anyway imo :y
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Contact cleaner won't work on the first film type MAFs (it does on the old hot wire ones).
Of the MAF is causing a lean mix then the lambda won't switch
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The MAF value is about 9.1 Kg/h which is a bit low.
any sign of a vac leak, pipe not fitted on inlet, brake servo pipe ok?
I would say for a 2.2 at hot idle that 9kg/hr is the lower end of normal.
I would have thought there would be some lamda activity, even if MAF was low, and the the LT trim would move drastically from 0%.
I suspect that its not trimming because it can't see any lamda activity, thus is ignoring it.
What d'ya reckon?
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Contact cleaner won't work on the first film type MAFs (it does on the old hot wire ones).
Of the MAF is causing a lean mix then the lambda won't switch
I accept what you are saying ... but don't understand why :( so I ask in order to learn ....
Assuming "Closed Loop"
If the MAF is low, yes the initial fuel from the ECU will also be low but should still be in the correct "ratio" to what the MAF "thinks" rather than what is so the mixture is lean - understand that bit .....
....if the lambda then senses that lean mix, surely the ECU should ADD fuel to correct this - that's what closed loop is all about ?? So I would have thought a low reading MAF would give high fuel trims as the ECU/MAF/Lambda all "fight" for control ?? then the fuel mix richens and the lambda starts to work as normal ??
Once the MAF is unplugged the system reverts to a "default" setting ?? and seems to increase the fuel as the engine revs much more freely, but the lambda is still not cycling so still running lean - which would explain the loss of power I suppose ??? but why does it stay so lean when MAF unplugged ??
Confused of North Wilts :)
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Sorry for coming back to this one .. but a further thought (dangerous I know) has left me even more confused than the questions above did ....
If the MAF is under reading to a large(ish?) extent, and the ECU only gives MAF rated fuel .. then it runs lean .... yup .. as said ... got that .....
however, if my thoughts in the above post are totally wrong, the engine stays lean which accounts for the loss of power ...... why then does it fail the MOT on emissions ??? emissions cannot be "high" on a lean running engine ??? can they ???
REALLY confused of North Wilts now ... :(
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If you go too lean, HCs can go up again due to misfiring.
Described halfway through here: http://www.autoshop101.com/forms/h55.pdf
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My head hurts too ???
Just a brief update: I cleaned the MAF sensor using an electronics cleaning spray (shouldn't affect any electronic components) and took the car for a run. I thought the problem was solved as initially it seemed to run just as I would expect but once it started to warm up the hesitation was back but nothing like as bad as it had been although I'm finding it hard to be objective about this. I should point out that I did reconnect the MAF sensor for this test. Does this support the idea that it is the MAF sensor causing the problem? A new sensor is on the way and will hopefully arrive before the weekend is out.
Thanks again to Nige for taking so much time helping sort this one out. I'm not sure if it helps 'Confused of N. Wilts' but I wonder if this has been a simple problem of a duff sensor sending data that puts the ecu out of range and therefore making any other inputs meaningless?? This would explain the fact that the lambdas are not switching as the ecu has now 'locked' into an extreme solution. This is probably what has been discussed (?) but I need to make sense of it in my relatively simple terms.
Once the MAF sensor has been fitted I'll post an update. Once again....thanks for all the inputs.
Tom
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If you go too lean, HCs can go up again due to misfiring.
Described halfway through here: http://www.autoshop101.com/forms/h55.pdf
Indeed. Plus the catalytic converter won't be active unless the mixture is centred around stoichiometric, so what little CO it does generate will go straight through.
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Fitted the new MAF sensor and engine starts well . :y..this is with the original lambda sensor in place, not the new one. Seemed a little hesitant a few times and the gear box seemed less smooth than usual but after a good run everything seem perfectly normal in terms of how it runs. The only downside is that the yellow light was back on and the same fuel trim error message (P0170) was there, as were two other error messages P0100 Air Mass Flow circuit error and one the number I forget but was the engine torque error. Cleared the codes and had another run and the error codes have not returned.
After the engine has cooled a little I'll change the lambda sensor to the new one and see how it goes. So it looks like the AMF sensor was the problem though I remain suspicious that the old lambda sensor may after all be duff.
This has been an interesting experience and I have learned lots. I chose the title of the thread because having had all the weird errors generated by a bad cam sensor in the past I had decided that there is a great risk of being misled or confused by the codes and so it turned out to be. Thanks to Entwood and the other inputs we seem to have cracked it. I'm keeping an eye on the error codes but now I won't be so readilly intimidated by them!
What a fantastic resource this site is 8).
Tom
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Nice one :)
I'd be intrigued to see how the lambda is switching on both old and new sensors ... but sounds like you are getting there :y :y :y
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I can't check the switching but have just returned from another run with the new lambda sensor fitted and I have to say that the car is running better than before all the problems following the MOT :y :) :y. No error codes - no yellow dash lights so feeling a little smug. I'm just waiting for the engine to cool down a little then I'm off to change the oil: this will definitely be an antidote to any smugness as it's already touching on freezing here!
I'm off to Cumbria tomorrow for a couple of weeks and, if you're up to it, we could have a look at that lambda switching.
Tom
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I can't check the switching but have just returned from another run with the new lambda sensor fitted and I have to say that the car is running better than before all the problems following the MOT :y :) :y. No error codes - no yellow dash lights so feeling a little smug. I'm just waiting for the engine to cool down a little then I'm off to change the oil: this will definitely be an antidote to any smugness as it's already touching on freezing here!
I'm off to Cumbria tomorrow for a couple of weeks and, if you're up to it, we could have a look at that lambda switching.
Tom
Have a good run .. watch the weather its a tad cold and white up there I believe :) If you want the live data checked any time just call .. you have the number :)
I'm slowly convinced you were unfortunate to have a double fault, MAF and Lambda .. :(