Need help please! Rough Idle, Not MAS

[MikeL]

Hey guys, my 00 W202 C230K recently hit 83K miles and its starting to act up. When I am in Drive and at idle, my car will jolt, shake and sputter, its kind surges of makes the rpm dance, jumping up and down. My rpm at idle is at 600 rpm, is this correct? Prior, I searched and others told me the problem is the Mass air flow sensor. I changed the MAS, air filter and I have a new fuel filter that I have to put in. I also flushed/cleaned in the gasoline/fuel injectors. My friend's BMW had a similar problem but his car wouldnt idle at all. If his car wasnt moving, the car would just die. He had to replace his actuator, which im hoping its not that because that is quite costly from what I understand? Also, does anyone know how long the spark plug intervals are? I think I am in need of changing those as well. Which ones are a better upgrade from stock? Any ideas guys? Thanks in advance, Any help will be greatly appreciated

[ryhi]

could be ur fuel filter. also.. check your intercooler pipes where the maf sensor is. i remember i had similar prolems when i hit a HUGE dip and the piping became loose.

[SLAMMED_C]

It may be a good idea to replace the spark plugs.. Im not sur eon the mileage.. either 8?,???, or 96,000km or 4 years for spark plugs.. the bes thing to do is hook it up to a computer and check actual values.. see what cylinders are having a possible missfire from what you are saying. you can check the supressor resistance..
remove the spark plug cover, remove the bolts holding in the coils, remove the coils and supressors,
check each supressor with a multi-meter.
I believe there should be 2000K Ohms of resistance.. the value is printed on the supressor, so double check that.
is your check enigne light on?
The M111 is a somewhat harsh engine, not super smooth at idle.. and small "missfires" like there commonly is wont set off the check engine light..

[alphanumeric]

is your intake system OEM or modified? I put an intake on mine..and it ran fine.. untill 1 day my idle was like shit.. from sucking in all the hot air .. put OEM back in and everything works fine

[1st_C_Class]

My C280 did that as well. It turned out to be a vacuum leak in the valve located between the intake and the brake booster. I have seen other posts about the same problem as well. It was fine one day and surged and shook the next day. Surprisingly, the CEL never came on during a day of limping around.

The plus side was that it was a lot cheaper than an MAS or throttle actuator.


Tim