Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: MikeDundee on 10 July 2007, 20:30:28
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Jaime done the Tech 2 on the car today and came up with fault codes P0170 & P0173 seems to think this may be pointing towards the Lambda sensor?.......
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Its actually BANK 1 fuel trim malfunction and BANK 2 fuel trim malfunction.
Cleared the codes, then a live data showed the trim values adjusting as expected. The o2 sensors B1S1 and B2S1 were doing the normal rich/lean process. The o2 sensors B1S2 and B2S2 were reading constant Lean.
The car appears to be using quite a lot of oil, hint maybe of cam gaskets. If oil was burning in cylinders, would this affect emmission feedback?
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Dodgy fuel is a possibility. This is what mine barfed up when it had a dodgy tankful from Morrisons during the contaminated fuel fiasco in February. The fact that both banks are complaining makes me think it's something common to both. Fuel is a possibility, as is an air leak or metering problem, although that may well have thrown up a MAF sensor fault instead.
Could be that the Lambda sensors have been misreading due to oil consumption I guess but I think they can cope with a fair amount of oil consumption before becoming inaccurate. I'd say it's unlikely to be Lambda sensors as both are complaining. Unless something has killed them both at the same time?
Kevin
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Dodgy fuel is a possibility. This is what mine barfed up when it had a dodgy tankful from Morrisons during the contaminated fuel fiasco in February. The fact that both banks are complaining makes me think it's something common to both. Fuel is a possibility, as is an air leak or metering problem, although that may well have thrown up a MAF sensor fault instead.
Could be that the Lambda sensors have been misreading due to oil consumption I guess but I think they can cope with a fair amount of oil consumption before becoming inaccurate. I'd say it's unlikely to be Lambda sensors as both are complaining. Unless something has killed them both at the same time?
Kevin
Mmmm, I did put Morrisons fuel in it the week before last, normally always use BP, and have since used up Morrisons and back to BP again.
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All the gaskets where done on the engine e.g., sump, cams etc.. according to my mate (when I was in Thailand), I am waiting on the receipt to confirm but he is certain they were all done.
Could it be the o2 sensor playing up?
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I think (but would like confirmation) that the BxS2 sensors are the ones post cat. These were always reading lean. Not sure if this is normal. The BxS1 sensors (pre cat ones?) were doing the Rich/lean constant cycle as expected.
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I think (but would like confirmation) that the BxS2 sensors are the ones post cat. These were always reading lean. Not sure if this is normal. The BxS1 sensors (pre cat ones?) were doing the Rich/lean constant cycle as expected.
Thanks Jaime, what is the difference between pre- and post :-[
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I think (but would like confirmation) that the BxS2 sensors are the ones post cat. These were always reading lean. Not sure if this is normal. The BxS1 sensors (pre cat ones?) were doing the Rich/lean constant cycle as expected.
Thanks Jaime, what is the difference between pre- and post :-[
2 sensors are in exhaust between engine and cat, and the post cat ones are fitted in exhaust between cat and middle section of exhaust.
Sorry for not explaining myself properly first time.
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I would speculate that fuel trim is controlled by the pre-cat sensors (these are the ones that are cycling, so it must be). As it was the fuel trim that caused the complaint something was causing them to correct out of the normal range. The post-cat ones are presumably there to detect when the cats are working properly so I guess they don't change state once the cats are up to temperature.
I'd expect an additional fault code if the reading from the post cats was wrong although I'm trying to think if they should be lean or rich. :-/
Kevin
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Jaime, has already suggested checking for air leaks and vauxhall have suggested checking the air mass meter (whereabouts it that?), the mass meter?
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Jaime, has already suggested checking for air leaks and vauxhall have suggested checking the air mass meter (whereabouts it that?), the mass meter?
MAF is between air filter and throttle body - in your case (V6), follow pipe from airbox (where filter is), as it goes through 90 degrees downwards, its the unit just below the 90 degree bend.
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What you have to consider is that these sensors detect oxygen presence and by lean the actual reading is no oxygen...............
Its not inconceivable that the CATs act as a slight buffer for unburnt fuel and oxygen and hence everything leaving them has no oxygen (a good thing) so you could infer that always lean is the correct state.
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What you have to consider is that these sensors detect oxygen presence and by lean the actual reading is no oxygen...............
Its not inconceivable that the CATs act as a slight buffer for unburnt fuel and oxygen and hence everything leaving them has no oxygen (a good thing) so you could infer that always lean is the correct state.
Yeah, wasn't sure what the post cat readings should be. Ta.
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They way I see it is that when it runs slightly rich, any fuel vapour will sit on the cat and flash over when the next lean pulse appears and hence you get no O2 after the cat....
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What you have to consider is that these sensors detect oxygen presence and by lean the actual reading is no oxygen...............
Its not inconceivable that the CATs act as a slight buffer for unburnt fuel and oxygen and hence everything leaving them has no oxygen (a good thing) so you could infer that always lean is the correct state.
Yes, that's right. Any unburnt hydrocarbons will react with oxygen in the cat.
However, a lean mixture implys the presence of oxygen in the exhaust. You have put less fuel in than you have oxygen to react with it so you must end up with some spare oxygen in the exhaust, surely?
You need a rich mixture to remove all the oxygen because you'll never have complete break down of all the oxygen in the air unless you have a slight excess of fuel, and this is what I couldn't get my head around.
Not sure what the after cat sensors are telling the ECU now. :-/ Unless, it's that if there is not spare oxygen after the cat (not reading lean) then the engine needs to be leaned a little to give the cat some more oxygen wo work with.
Off to wikipedia...
Kevin
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.. actually, I think the cat is relinquishing oxygen into the exhaust when it breaks down CO and NOx from the exhaust gases so that's probably why it reads lean, and would start blipping up to rich in unison with the front sensor if the cat were not working.
Kevin
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Wikipedia says (rather vaguely):
The second sort of diagnostic is more complex and is a result of the California OBD-II rule (though temperature sensors are sometimes used for this). In vehicles with OBD-II, a second oxygen sensor is fitted after the catalytic converter to monitor the O2 levels. The on-board computer makes comparisons to the readings of the two sensors. If both sensors give the same output, the catalytic converter is non-functioning, and must be replaced. It will also spot less serious damage to a catalytic converter, such as the use of racing fuel in an on-road vehicle. Lead is still legal in racing fuel, and use of as little as half a tank of leaded fuel will cause enough damage for the computer to notice, and warn the operator that the converter is not functioning properly.
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Blocked air filter?????
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Ok folks thanks for all the feedback so far, great stuff :y...so on saturday I am going to be cleaning out the breathers (nothing to do with this problem), and checking for air leaks, and looking at the MAF meter (even though not sure what I am looking for when checking).
So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
Please forgive me folks as I am by no means a mechanic, but will atempt minor jobs. :-[
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So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
I wouldn't say you have a cat problem, TBH. Did the fault codes recurr after they were cleared?
I think the cycling of the front sensors proves they are working to some degree. The rear sensors are reading constant lean which I think is OK and means the cats are working. The problem is that the front lambda sensors have caused too great a fuelling correction and put the fault light on. This could be due to two failed lambda sensors but I'd say this is unlikely. More likely is that something else is feeding the ECU with duff information which is causing it to correct more than it should, or something has contaminated the lambda sensors.
Check for anything likely to cause an air leak while you're doing the breathers. It might be worth putting a tankful of decent fuel through it, and trying some injector cleaner just in case the fuel system is not delivering fuel as it should. I guess air filter is a possibility although the MAF should have been reading the correct airflow even if this was restrictive. It's worth giving the throttle body a clean while you're at it.
Has the fuel filter been changed recently?
Kevin
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Ok folks thanks for all the feedback so far, great stuff :y...so on saturday I am going to be cleaning out the breathers (nothing to do with this problem), and checking for air leaks, and looking at the MAF meter (even though not sure what I am looking for when checking).
So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
Please forgive me folks as I am by no means a mechanic, but will atempt minor jobs. :-[
Dont think you will have an air leak.....as ECU would be recording a MAF sensor fault.....when you find the MAF sensor.....dont go prodding it....they are fairly delicate.....just inspect visually for dirt on it....if it is dirty....they can be cleaned.....i think i read somewhere as gently swirling about in a container of white spirit does the trick......BUT wait till someone else advises how to clean it......i tend to melt things when i try cleaning ;D Altho my expansion bottle seems to have survived the abuse i gave it ::)
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So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
I wouldn't say you have a cat problem, TBH. Did the fault codes recurr after they were cleared?
I think the cycling of the front sensors proves they are working to some degree. The rear sensors are reading constant lean which I think is OK and means the cats are working. The problem is that the front lambda sensors have caused too great a fuelling correction and put the fault light on. This could be due to two failed lambda sensors but I'd say this is unlikely. More likely is that something else is feeding the ECU with duff information which is causing it to correct more than it should, or something has contaminated the lambda sensors.
Check for anything likely to cause an air leak while you're doing the breathers. It might be worth putting a tankful of decent fuel through it, and trying some injector cleaner just in case the fuel system is not delivering fuel as it should. I guess air filter is a possibility although the MAF should have been reading the correct airflow even if this was restrictive. It's worth giving the throttle body a clean while you're at it.
Has the fuel filter been changed recently?
Kevin
I cleared the codes, and we went for a little drive whilst I did a live data. pre-cat sensors looked fine, wasn't sure about post-cat (as I wasn't sure what they should read). Everything else looked fine. EML stayed off. A couple of hours later, he called me to say the EML had popped on again :(
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So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
I wouldn't say you have a cat problem, TBH. Did the fault codes recurr after they were cleared?
I think the cycling of the front sensors proves they are working to some degree. The rear sensors are reading constant lean which I think is OK and means the cats are working. The problem is that the front lambda sensors have caused too great a fuelling correction and put the fault light on. This could be due to two failed lambda sensors but I'd say this is unlikely. More likely is that something else is feeding the ECU with duff information which is causing it to correct more than it should, or something has contaminated the lambda sensors.
Check for anything likely to cause an air leak while you're doing the breathers. It might be worth putting a tankful of decent fuel through it, and trying some injector cleaner just in case the fuel system is not delivering fuel as it should. I guess air filter is a possibility although the MAF should have been reading the correct airflow even if this was restrictive. It's worth giving the throttle body a clean while you're at it.
Has the fuel filter been changed recently?
Kevin
No the fuel filter has'nt been changed since I boUght it in Nov 2003, I always use BP stuff apart from the other eek wehn I topped it up with Morisson fuel. I put Wynns injector cleaner in before I went up to see TB on Tuesday. Throttle body, book of lies recommends new seals, so may have to leave that if I can't get the seals, But I would have assumed when the seals where all done in April the y would have had to remove the throttle body and replace the seals in any case, even though they may have not cleaned the throttle body.
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So the way I see it so far Lambda's are Ok, o2 sensors are OK, May have a problem with the CAT?
I wouldn't say you have a cat problem, TBH. Did the fault codes recurr after they were cleared?
I think the cycling of the front sensors proves they are working to some degree. The rear sensors are reading constant lean which I think is OK and means the cats are working. The problem is that the front lambda sensors have caused too great a fuelling correction and put the fault light on. This could be due to two failed lambda sensors but I'd say this is unlikely. More likely is that something else is feeding the ECU with duff information which is causing it to correct more than it should, or something has contaminated the lambda sensors.
Check for anything likely to cause an air leak while you're doing the breathers. It might be worth putting a tankful of decent fuel through it, and trying some injector cleaner just in case the fuel system is not delivering fuel as it should. I guess air filter is a possibility although the MAF should have been reading the correct airflow even if this was restrictive. It's worth giving the throttle body a clean while you're at it.
Has the fuel filter been changed recently?
Kevin
No the fuel filter has'nt been changed since I boUght it in Nov 2003, I always use BP stuff apart from the other eek wehn I topped it up with Morisson fuel. I put Wynns injector cleaner in before I went up to see TB on Tuesday. Throttle body, book of lies recommends new seals, so may have to leave that if I can't get the seals, But I would have assumed when the seals where all done in April the y would have had to remove the throttle body and replace the seals in any case, even though they may have not cleaned the throttle body.
Change the fuel filter - its about £5 or £6 on TC, but remember the 2 little clips as well (50p each)
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
Are you also checking oil on dipstick?
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
Are you also checking oil on dipstick?
Yes have been, just checked the dipstick, oil up to the first notch, which means I need to put around 1 litre back in. What i can't get my head round is that there always oil on the last notch, but nothing on the notches in between, have to assume this is normal :-[
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
Are you also checking oil on dipstick?
Yes have been, just checked the dipstick, oil up to the first notch, which means I need to put around 4 litres in. What i can't get my head round is that there always oil on the last notch, but nothing on the notches in between, have to assume this is normal :-[
Eh? there are 2 marks on v6 one - min and max. Difference between min and max is 1l
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
Are you also checking oil on dipstick?
Yes have been, just checked the dipstick, oil up to the first notch, which means I need to put around 4 litres in. What i can't get my head round is that there always oil on the last notch, but nothing on the notches in between, have to assume this is normal :-[
Eh? there are 2 marks on v6 one - min and max. Difference between min and max is 1l
:-[ yeah fair enough, :-[ was counting the notches on the dipstick, which there are 4 of :-[, potentially may have been topping it up too much?, been looking for one of those oil jug thingy's but can't seem to find one, to avoid over filling :-X....could that contribute to the Tech 2 readings?
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Throttle body is a long shot anyway, TBH. Any air that goes through it is metered so even if it's dirty it probably wouldn't contribute to the problem.
Can you remember what you were doing when the light came on again?
How much oil is it losing at the moment? I wonder if oil consumption is affecting the lambda sensor readings :-/
Kevin
Before I left Biling, I topped up the oil, and after I left was on the dual carriageway, some idiot in front hit his brakes cos someone in front of him, I obviously had to do the same thats when the light came on, reckon its taking about a litre plus per 1,300 miles. However, before i got to TB's work on Tuesday Oil check came on then never showed again till just before oxford, seems to come on and off at times. :-/
Are you also checking oil on dipstick?
Yes have been, just checked the dipstick, oil up to the first notch, which means I need to put around 4 litres in. What i can't get my head round is that there always oil on the last notch, but nothing on the notches in between, have to assume this is normal :-[
Eh? there are 2 marks on v6 one - min and max. Difference between min and max is 1l
:-[ yeah fair enough, :-[ was counting the notches on the dipstick, which there are 4 of :-[, potentially may have been topping it up too much?, been looking for one of those oil jug thingy's but can't seem to find one, to avoid over filling :-X....could that contribute to the Tech 2 readings?
If you are overfilling, yes. And that won't help with your suspect cam covers?
4 marks? Trying to remember if a 2.6 dipstick is different to 2.5 one which only has 2 marks?
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4 marks? Trying to remember if a 2.6 dipstick is different to 2.5 one which only has 2 marks?
Mine has 4 notches. It's like a section of steel cable with a slug of lead moulded on the end. This has 4 notches cut into it. Presumably the top notch is full and the bottom one is empty.
Kevin
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4 marks? Trying to remember if a 2.6 dipstick is different to 2.5 one which only has 2 marks?
Mine has 4 notches. It's like a section of steel cable with a slug of lead moulded on the end. This has 4 notches cut into it. Presumably the top notch is full and the bottom one is empty.
Kevin
Ah, right, yes, I have seen that sort. Top notch = max...
Though still only 1l from min to max, not 4l!!!
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4 marks? Trying to remember if a 2.6 dipstick is different to 2.5 one which only has 2 marks?
Mine has 4 notches. It's like a section of steel cable with a slug of lead moulded on the end. This has 4 notches cut into it. Presumably the top notch is full and the bottom one is empty.
Kevin
Oil up to the first notch, and oil from the fourth notch up, will take a pic in the morning and post it up, the nothces in between nothing?, I keep assuming it is catching oil as I put it back in or take it back out?
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Though still only 1l from min to max, not 4l!!!
EEK! :o Yes, just re-read that. Min to max is not much oil. I'd be wary of putting a litre straight in without checking after the first 500ml, TBH.
Kevin
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Though still only 1l from min to max, not 4l!!!
EEK! :o Yes, just re-read that. Min to max is not much oil. I'd be wary of putting a litre straight in without checking after the first 500ml, TBH.
Kevin
OK folks will accept idiot of the week for that one ::)....changing fuel filter is slightly out of my bounds at the mo, as would need to get under the car and have nothing to get the car up with.
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Just checked the oil this morning got a better reading as engine was still a bit warm last night, oil up to the second notch only.
apologies for picture quality, batteries on camera ran out :-X
(http://i85.photobucket.com/albums/k65/mickdundee_01/2004_0209keswick2007billing0004.jpg)