W156 Misfire



Cam solenoids and cam adjustment gears were replaced when heads were done.
Cause or symptom the injector turns off at light load intermittnantly
I did note that my exhaust cam positon values were fluctuating between -10 and +14 while cruising at that low rpm though
Both intakes were approx. +17 , and the other exhaust was about -6



How did you capture/measure that?
I have a theory though. Disconnect the cam position sensor on Bank 2. Go for a drive. See if it still misfires without the cam adjuster running.
If its fine, then its either the cam adjuster or the cam position sensor
Last edited by kkkk; Aug 30, 2019 at 09:51 AM.
The Best of Mercedes & AMG
the M156 engine was CAD designed so I'd doubt the head flow characteristics to allow for a deviation of 11%. deviation is unavoidable with OEM built engines, but not of a spread of 11%. I'd look to maybe the possibility of air flow restriction of some sort? it wouldn't be a fuel flow issue as fueling will be based off metered air and oxygen sensor reading.
does your trims always have a 11% spread, or was it just this instance? my LTFT's with larger injectors and e85 tend to have a spread of about 3-7% at times, but never static.
anybody else here have any thoughts?
Feel bad as they took him to the cleaners changing everything but the one thing that is making noise.




Im just wondering maybe someone skipped a step or something when putting the car back together after the headbolt install
https://www.youtube.com/watch?v=XhgVA6Ajm5w
Did your misfire come after the headbolt install dogtag?
What are your long term fuel trims like?
I hope you got that cleared up.
I havnt looked to see what it reads with the intake cam solenoid unplugged, or if it defaults to a safe setting with the exhaust cam solenoid unpolugged.



With brand new cam solenoids plugged in, misfire on cylinder 7 still present.
Unplug exhaust cam solenoid. Misfire goes away entirely....at this point I'm completely at a loss.







