Lowacura

Hey all, its been about 2 years now since i have been troubleshooting this dang car…. WITHOUT A STAR program and a basic code reader. But i have no codes at the moment….

ive done quite a bit of work to the car that ill list below after i explain my problem…

2007 mercedes e320 bluetec OM642
car has 138400 miles

The issue:

ive had this shudder jitter when light on the throttle as if the gas just cuts on and off for the last 2 years. And now recently i am getting a consistent surge in rpm when i come to a complete stop and sometimes when i put it in park. So i dont think its transmission related? Its as if the gas is still pressed and gets a signal late to release. The surge is much more consistent than the judder but thats because i learned not to feather the throttle now.

update:
i tried to rev the engine with and without the ac and it seems to happen much more when the ac is on. Could it be a bad ac unit? Ac blows out excellent.


so my thoughts are possibly:

swirl flap? Never replaced it
gas pedal position sensor?
throttle position sensor?
egr valve?

Any other suggestions?

i pulled the turbo actuator off and took it apart to inspect the inside and it all looked great, all solders were fine.

The list of work done: most of it done 13k miles ago unless stated
oil cooler seals
transmission fluid and filter
intercooler hose pipe to the intake
Changed all the engine mounts including center carrier mount which made the car so much smoother
replaced the fuel filter 4000 miles ago
replaced the oil filter gasket 200 miles ago
replaced the y pipe intake with maf sensors just done 200 miles ago same issue
replaced the breather valve and installed a catch can. 4000 miles ago
Oil changed from liqumoly toptec 5w30 to mobile1 esp 5w30 less than 300 miles ago

Wifey says its time to let this car go but its been a good car and i would hate to see this thing go if its a simple fix. Good gas mileage, diesel, ac words excellent, speakers are great, and its a good road trip car.


Thanks for the help in advance!

doxland

I've been facing the same thing. At a dead idle engine rpm bounces just slightly; when holding the rpm slightly above idle it does the same. No thing discovered so far.
This is on a 2005 E320 CDI.

Lowacura

I went to a euro specialist today to make an appointment. I explained my issue and he said it sounds like a vacuum leak. He also mentioned there was a bulletin that came out for the throttle pedal sensor. So I am thinking of doing a smoke test myself if i have the time before monday. If i cant figure it out then ill just take it in to him so he can hopefully figure it out.