Help - Fluctuating idle C36

[bongC36]

Gents, My 95 C36 suddenly developed a peculiar idle today. It fluctuates from 1000 to 1700 RPM in approx 1-second cycles, in gear or in neutral. This is scary because the car speeds up by itself when the RPM climbs and brakes can hardly hold it.

I shut the motor off but the problem was still there when I re-started. I shut it down once again and when I fired it up after a couple of seconds, the idle was now steady but very low (400-450 RPM). There are no check engine lights showing and everything else seems normal.

I did a search but can't find any posts with these particular symptoms. The plugs are about 1 year old (less than 15,000 km) and car is very smooth and powerful until today.

Assistance in troubleshooting this malady is highly appreciated.

[kameraguy]

Holy crap....sounds terrible. Well, I recall seeing threads related to fluctuating idles due to defective MAS sensors....maybe that would be something to check out?

Do you know anyone who can check for trouble codes too? This sounds like a problem that would document something.

[Alps]

sounds like the good old MAS sensor to me too!

theres been loadsa threads in the past on this!

let us know if you cant find any more tdetails

[J Irwan]

Bong

I would check your MAF first thing ...


if you have fluctuating idle 90% of the time MAF would be the culprit.. ;)



Regardz,

J Irwan

[bongC36]

Thanks for the tips guys, I kind of figured it is related to the MAS too because we opened up the air intake box a few days ago to change the air cleaner. How do I check if the MAS is defective? I live quite far from the MB dealer.

[Dr. ///AMG]

moved to engine tuning.