C43 Idling Problem

[bigasotonuk]

Hi fellow forum members,
I have a slight problem with my C43 AMG. Ever since buying approx. 3 months ago
When starting from cold i put it into D and the car takes up the drive and the engine dies. Leave it for 2-3 minutes idling put it in D and its perfect. The MAF was replaced approx.12-18 months ago.
Any ideas?

 

[angus falconer]

Hmmm....haven't had this actual problem. Have you stuck it on a star dianostics unit?

I would assume it's related to either electrics/ignition or fuel.

I had a faulty coil pack and a couple of duff leads on my last one which gave some spurious faults on the diagnostics. Problem resolved by laborious manual testing of all the compenents by BSG Mercedes.

I had faulty crank sensors on both of mine but the symptoms are difference - cold starts OK but hot starts become increasingly hard.

Failing that maybe one of the many electrical command units...?

Failing that maybe a fueling problem?

 

[bigasotonuk]

Hi,
Cheers for the reply, I have,nt as yet even considered putting it on a diagnostic as the problem is so slight as i say. Something i forgot to say which may have some bearing on it is the air-con by default is on, when on the engine hunts slightly.
Though possible i find it hard to believe it to be ignition problems as the car runs so very well and smooth and on a run she will give nearly 30mpg.
I had similar problem on my C230K turned out it was throttle control valve (caused uneven idle at all times).
Could it be this? Have i even got a throttle control valve on the C43.

 

[angus falconer]

I had similar problem on my C230K turned out it was throttle control valve (caused uneven idle at all times).
Could it be this? Have i even got a throttle control valve on the C43.

I remember early Golf GTI's and Sciroccos had a recurring problem with the idle control unit which would cause similar symptoms.

At a guess I would suggest that most injected engines have similar components so it's worth looking into.

Why not call you local indie - they should be able to give you a streer.

 

[type49]

There is an air-bleed pipe that splits on these. It's at the back of the engine, starts in the middle just in front of the throttle housing, goes straight towards the NS wing & then turns towards the front. About 10" long. Also it is possible to knock the MAF out of the throttle housing when refitting the top air-cleaner box back on. This can cause odd running faults. Put a smear of grease on when refitting.

 

[bigasotonuk]

HI,
Thanks for the suggestion i will check this pipe out and also suggested the MAF being displaced, will keep you posted.

 

[mattkh]

I remember early Golf GTI's and Sciroccos had a recurring problem with the idle control unit which would cause similar symptoms..

Hi
Do you mean the idle control unit/relay that was behind the dash on the passenger side ???

 

[angus falconer]

Hi
Do you mean the idle control unit/relay that was behind the dash on the passenger side ???

I've no idea. I just remember that when my mates ran GTI's they quite often developed a lumpy idle and the fix was the idle controller.

 

[vtwin]

Fuel pump?

 

[MarkCL]

Might even be O2 sensor - not sure but I think Andy has this sorted now? :?:

Cheers,
Mark

 

[bigasotonuk]

No still not sorted unfortunatetly,
I,m hoping that it will be sorted when its serviced next time fingers crossed.
But talking about the O2 sensor it did only just pass the emissions last MOT so that maybe something to look at.
Do O2 sensors wear out?
Mark you had yours replaced did,nt you? I don,t suppose you can remember how much they were do you?

 

[MarkCL]

Hi Andy - Yes they do wear out unfortunately and yup, one of mine (yes, we have two - one for each bank of 4 cylinders so it's twice as expensive as usual lol! ) was indeed faulty - Oliver did a diagnostics run and found the fault so I got it changed out for a new one. Don't think it was too evil on cost - don't have the bill to hand though to be sure but say £100-150ish I think + the labour to change it out. I'll check my bill when I get home and let you know for sure though My idle speed was all to pot too - one of the reasons why Oliver checked the O2 sensors I think so it could solve your problem

Cheers,
Mark

 

[MM's C43 London]

I had exactly the same problem with mine. They replaced the Crankshaft sensor and it run alot better. warning been only two weeks but I hav not had a problem and its running better

 

[MarkCL]

Hi Andy - just to confirm the price n the O2 sensor in case you're interested, it was £95 + VAT and that was the sensor + fitting If you haven't had your crank sensor changed either then it might well be worth getting that done too as that really covers all the bases then.

Cheers,
Mark

 

[bigasotonuk]

Hi,
Been away with work, only just got back today thank you for the replies,
Was that £95+VAT each?
Personnally I,m thinking problem is the O2 sensor(s) as the emissions only just passed the MOT last year.
I,ll try the crank sensor if the O2 sensor(s) fail to fix it.

 

[MarkCL]

Was that £95+VAT each?

Yup - but considering that was the cost fitted I didn't think it was that bad to be honest Only one of my lambda sensors was posting any errors, the other one is still fine. No idea why one had gone but not the other, but then it might have had something to do with the spark plugs - one or two were still the original MB ones from when the car was new, the others were Vauxhall plugs for some reason Needless to say, Oliver changed them all for proper MB ones and also the plug leads at the same time just to cover all the bases. No real damage done, just wasn't performing like it should - with that lot changed out it was back to running sweet as you'd like needless to say 8)

Cheers,
Mark