W202 erratic idle on cold start & backfire

[c200_impressor]

Hi. Need some advice....

I have a 1998 C200 W202 which idles erratically between around 500 and 1500 rpm on a cold start. Also the engine seems to 'kick' when driving and occasionally 'pops' which i guess is a backfire. The problem clears after a few minutes once the engine warms up.

I have replaced (with new parts):
- Mass air flow sensor
- Ignition coils
- Spark plugs
- Ignition leads

But the problem is still occurring and am now at loss as to what it is!!???

Any advice would be much appreciated. Cheers.

 

[kamalpatel12448]

Get the fault read on Star machine?

 

[martyz]

I have replaced (with new parts):
- Mass air flow sensor
- Ignition coils
- Spark plugs
- Ignition lead

Maf Bosch ? if not you will have problems

 

[c200_impressor]

Maf isn't Bosch but problem is the same even with maf disconnected/bypassed... so is not the maf.

All connections of ignition leads and coils checked and ok.

Cheapest quote I had to get codes read was about £90. No way will I pay that just for a code check. Total rip off. That's why i've posted this question.

 

[martyz]

Have you checked fuel rail pressure.fuel flow(blocked filter) ?
it could be one of many reasons.but my advice is after basic checks are carried out and
you are still drawing blanks find yourself a good indie with star and get it diagnosed. I am sure you can get that done for less than £90.good luck

 

[Auto-mobile]

Remove throttle body, clean and reset adaptations, that should do it.

 

[Dieselman]

It sounds like the mixture is too lean when cold so I suspect it's either the coolant sensor or MAF.

 

[Rock]

hi, c200 impressor

Ive had exactly the same problem few months ago ( Oct 2011) and tried everything and felt selling my beloved C200k at one point than someone who knew about MB suggested to take out the trottle body, clean and replace.

BINGO...... it solved the idling etc there was allot of oil, debris in the trottle body. before ive changed the MAF 3 times...... at no expense to mines as i took it back to euro parts every time.

Suggest you get a local indie to do that as its allot of fiddling around it cost me £30 and about 45 mins all done.

Good luck

 

[c200_impressor]

Turned out to be dirty injectors. Couple of bottles of Redex OneShot did the job and still running perfectly 3 years later!