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Before I go digging into the car or get time that is, just wondering what are some common places for vacuum leaks that could cause this lean condition. When coldish the ltft start at around 6-8. and once warm get upto 16-18. close to setting a check engine p0171 code. Its not quite there yet but i think it may be on the horizon. Do the pcv fail on the m157 similar to some other european make and models? do they have a similar effect and cause lean conditions and lean codes? let me know if anyone has ran into something similar. car has 78k miles now.
It’s not lag. LTFT I stated were at idle. When cold and get worse as it is fully warmed up. Just trying to see if anyone here has ran into lean codes and what their fixes were. From what I see lean only at idle is usually some sort of vacuum leak or dirty worn maf sensors but not leaning toward maf since both would be very unlikely to go out at the same time. I’m strict about changing airfilters and only using Mann paper filters. I’m not into using kand n style due to poor filtration and don’t like the thought of ingesting dust on a motor with delicate cylinder walls like the m157. Thats just me though. Anyways, let hear from anyone with lean codes and what your fixes were. I can’t be the first one
Last edited by Matermerc; Feb 20, 2025 at 08:32 PM.
It’s not lag. LTFT I stated were at idle. When cold and get worse as it is fully warmed up. Just trying to see if anyone here has ran into lean codes and what their fixes were. From what I see lean only at idle is usually some sort of vacuum leak or dirty worn maf sensors but not leaning toward maf since both would be very unlikely to go out at the same time. I’m strict about changing airfilters and only using Mann paper filters. I’m not into using kand n style due to poor filtration and don’t like the thought of ingesting dust on a motor with delicate cylinder walls like the m157. Thats just me though. Anyways, let hear from anyone with lean codes and what your fixes were. I can’t be the first one
Ok you have lean engine without lag.
Definitely not spark related as engine is combusting satisfactorily.
Normally a cold engine is richer than in closed loop, yours is still too lean... then low fuel supply.
Are both bank LTFT nearly equal or normal with only one offset?
Last edited by CaliBenzDriver; Feb 20, 2025 at 08:56 PM.
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