Mersuman

Hello!

I'm Ilkka from Finland. I just registered to mbworld because of very tough problem with my w211 cdi. Any of old posts doesn't solve my problem...
After almost one year didnt get help any of local mechanics or dealers or Finnish forums.
You guys are my last hope

Shortly problem is high and rough idle when shift is park or neutral position.
And here is details:

- RPM jump to ~2000 when shift N or P position.
- Revs want drop below that and idle is rough and whole car shakes.
- Little push to throttle pedal and idle is smooth and normal.
- Taking leg off from pedal and revs stuck to 2000rpm and shaking start
- When engine cold it works fine, problems start after short ride.
- Nothing problems with driving, ONLY P and N.
- Diagnostic doesn't recognize any faults!

So far done:

- New ECU and transmission "ECU" also.
- New crank shaft position sensor.
- New fuel pressure sensor / valve.
- Injector pressures measured.
- All fuses taken off one by one when fault is on.
- All sensors plugged off when fault is on.
- Something else what i right now remember...

Sounds familiar to anyone?
It may sound simple failure but seems to be something else... Very tough and tricky problem, or is it

Best regards
-Ilkka

uraberg

In general:


Vacuum leak
Dirty throttle body,
Malfunctioning idle air control


I'd say, the problem is insufficient air at idle. Probably blocked air passages.

cmriv

not to familiar with this but see if theres a connector going to your gas pedal.... disconnect it and if your idle adjusts back to normal when in park or neutral theres your problem.

AMGAffalterbach

I would tend to agree with uraberg, it seems through the parts you've replaced that you've eliminated a large proportion of problems associated with the electronics / engine management side of things. My bet would be insufficient air as well.

alika808

+1 here, the above are caused for idle issues.