So I've been sort of chasing this for a while but as it's kind of minor haven't really gone too hard. There's plenty of threads on the internet about mixtures albeit usually running lean due to vaccum leaks and the like.
My S54 is running slightly rich though. Not enough to flag codes or anything. In fact it runs and drives perfectly. The only give away is when cold it's slightly smelly particularly noticeable in underground garages. Presumably this is because it's open loop (although do the LTFT still not apply even in open loop?). Once warmed up all is good.
LTFTs both sit about -7 to -9% when read via typical OBD apps or 0.93 to 0.91 in INPA or the ECUworx DME tool. I reset the adaptations and within about 20-30 minutes of driving they're back to where they were. e.g. after a clear then drive just now:
Running rich has a smaller list of things to look at. Car has about 100k kms on it so not high mileage and is pretty well looked after. I've had it for >10 years since about 60k kms
1) I have checked fuel pressure at 5 bar at idle with (vaccum?) hose removed and about 5.7 with it fitted and engine running which is right, well at least with the limits of reading my gauge. Thinking about that, shouldn't pressure drop with vacuum if that's a vacuum hose? I might have the numbers the wrong way around here - it's been a while since I measured. At the time they seemed right when I looked it up though.
2) Cleaned the MAF as a bit of an easy thing to try with little expectation it would do anything and it didn't. It is a Bosch unit and appears to the be original factory one as the plastic stamping showed 5/04 (car is a 08/2004 build)
3) There are no codes and there have never been any rich/lean type codes.
4) O2 sensors are original and likely the original factory parts although when cold they're ignored and it does run rich based on smell although that's hard to quantify and all vehicles run a bit richer when colder.
5) As both banks show essentially the same value, it largely rules out specific injectors, cylinders or banks (i.e. O2 sensors). So needs to be something common to both banks i.e. MAF or fuel pressure seem the main culprits.
6) Entire drivetrain etc is stock. Even the DME version etc look like the factory ones. Only "mod" is a Bluebus
I did also recently do a Beisan VANOS install along with valve adjustment, plugs, oil change, air/oil/fuel filter etc although this problem has been around for a long time before this - it just hasn't really been a priority to look at really.
Any ideas? I was thinking MAF but don't want to throw parts at it. I'm not sure what else it could be though. USD$150 delivered (for me) for a MAF is not going to break the bank if the general opinion of the knowledgable people here think it worth a punt.
My S54 is running slightly rich though. Not enough to flag codes or anything. In fact it runs and drives perfectly. The only give away is when cold it's slightly smelly particularly noticeable in underground garages. Presumably this is because it's open loop (although do the LTFT still not apply even in open loop?). Once warmed up all is good.
LTFTs both sit about -7 to -9% when read via typical OBD apps or 0.93 to 0.91 in INPA or the ECUworx DME tool. I reset the adaptations and within about 20-30 minutes of driving they're back to where they were. e.g. after a clear then drive just now:
Running rich has a smaller list of things to look at. Car has about 100k kms on it so not high mileage and is pretty well looked after. I've had it for >10 years since about 60k kms
1) I have checked fuel pressure at 5 bar at idle with (vaccum?) hose removed and about 5.7 with it fitted and engine running which is right, well at least with the limits of reading my gauge. Thinking about that, shouldn't pressure drop with vacuum if that's a vacuum hose? I might have the numbers the wrong way around here - it's been a while since I measured. At the time they seemed right when I looked it up though.
2) Cleaned the MAF as a bit of an easy thing to try with little expectation it would do anything and it didn't. It is a Bosch unit and appears to the be original factory one as the plastic stamping showed 5/04 (car is a 08/2004 build)
3) There are no codes and there have never been any rich/lean type codes.
4) O2 sensors are original and likely the original factory parts although when cold they're ignored and it does run rich based on smell although that's hard to quantify and all vehicles run a bit richer when colder.
5) As both banks show essentially the same value, it largely rules out specific injectors, cylinders or banks (i.e. O2 sensors). So needs to be something common to both banks i.e. MAF or fuel pressure seem the main culprits.
6) Entire drivetrain etc is stock. Even the DME version etc look like the factory ones. Only "mod" is a Bluebus
I did also recently do a Beisan VANOS install along with valve adjustment, plugs, oil change, air/oil/fuel filter etc although this problem has been around for a long time before this - it just hasn't really been a priority to look at really.
Any ideas? I was thinking MAF but don't want to throw parts at it. I'm not sure what else it could be though. USD$150 delivered (for me) for a MAF is not going to break the bank if the general opinion of the knowledgable people here think it worth a punt.
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