W108 3.5v8 warm running problem

I understand, that’s why he runs cold better than warm.
Thanks

Hello Dr,

A small update. I occluded the AAV with a small plug with a hole drilled through it. My hunting idle is now solved and it doesn’t get so cold here so I think this is ok. Again today the car stalled when at traffic lights after ten min of driving and wouldn’t start. I also noted it turning over rather slowly at this time. Two hours later it starts ok and I drive home. Could it be bad voltage regulator, battery or alternator causing this condition. I thought if MAP sensor then it should still turn over quickly? Btw MAP I have checked and resistances are ok and hose looks good. Haven’t done vacuum test as don’t have this tester. Thanks again,

Kind regards

Hemal

Hi Hemal,

I can confirm that D-Jetronic runs badly if your voltage drops too much.

you have to check vacuum leak of MAP sensor. Resistance is not enough. And I will not comment on your AAV closing . I also do not understand why you left a hole in it. It closes completely on hot engine when it works properly. Unless you live at 80°C environmental temperature an AAV still has work to do from 20° to 80°C engine temp.

Hi Volker,

Many thanks for your prompt reply. I will find a vacuum tester and check the MPS as per your guide.

Very frustrating to have to push the S class across an intersection!

Alternator tested ok so I am not sure why it wasn’t spinning over well after stalling…

Hi Volker

I hope you are well. I can confirm that the MAP sensor holds 15in of hg for more than 10 seconds. Where do you think I should go to next?

Kind regards

Hemal

Hi Hemal,

are you able to measure exhaust gases. Especially CO and HC ?