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P0172 coming and going, cryptic DAS message. EVAP problem?
Hello. I have a problem with my W211 (E280, 2009 M272 3.0L gasoline engine). I have the P0172 code coming and going for the past few years (if I drive long enough with the P0172, the P0175 comes up too). Infinite amount of shops failed to find the cause.
- When CEL illuminates, the car feels sluggish. Resetting the code restores the vehicle responsiveness.
- I have checked most of the common causes and the error remains.
- I cleared the MAF (not dirty), replaced the PCV valve (was replaced before), replaced injectors (were bad), spark plugs, etc.
- MAF, MAP and throttle position values are corelating.
- I am now monitoring the STFT and LTFT which seem OK.
- The error is now pending again (no CEL yet) but the OBD STFT and LTFT values do not seem to be that off.
- There is a cryptic message on the DAS: Module $7E8, MID=81 TID=80, Min=-4.5%, Max=4.5%, Value=-4.69% [FAILED]
- It seems like ranges for mixture adaptation but I am not sure. There is no other text.
- I have also monitored other parameters and the EVAP values seem unusual. I am attaching an image with EVAP, Fuel trims and engine RPM. They are all from the same cycle, aligned. The car was stopped once from around 08:01 to 08:05 (flat zero line on the RPM chart).
- The chart seems to show that the EVAP is higly active, with a trend line from around 10% to 50% in just 20 minutes of driving.
- I also attach oxygen sensor readings for reference.
If anyone could provide some insight, I would greatly appreaciate it.
The DAS system should be more precise and would suggest if the mixture formation for partial load for the right cylinder bank is below or beyond specific value. Also DAS has a very intuitive test for that. MAF or more likely the air leak around intake manifold.
The problem is in the EVAP system. For testing purposes, I refuel half of the gas tank only at the gas station. The CEL went away on its own, the car is responsive again and stopped shaking at idle. If anyone has had a similar issue, please let me know.
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P0172 coming and going, cryptic DAS message. EVAP problem?
