C220 CDI Eratic Shaking at Idle.

[Pillabenz]

Evening folks, Just bought another Mercedes. This time its a C220cdi Auto. 01 model.

Car dives excellent, very responsive, very pleased with it.

However, at idle its not very well, it idles at approx 650rpm, the whole car shakes, if i touch the throttle slightly and put it at 750 rpm its absoloutely fine.

Its worse when the engine is at full temp, its not as bad when the engine is cold, i assume the cold startsensor is compensating with the fuelling there.

I have today removed the EGR and cleaned it all making sure the shaft was free. Still the same.

I've checked intakes etc, injectors, no leaks anywhere, Unplugged the MAF sensor, seems to be the same except the revs hold for a second or so after revving with it unplugged so i dont think its that.

Tried turning off the heater booster setting, still the same.


Is there anything else i should do myself ?


Many thanks folks, car drives lovely otherwise. Glad to be back in a Benz.

Pilla.

 

[Pendragon]

Good luck on solving the problem as it seems to be a common fault. I spent over £600.00 on parts for mine because people said it was this, that or the other . Even Mercedes couldn't solve the problem or even find one.

I put my STAR on it and no faults at all.

Cured it last weekend when I gave it a good blast from Cardiff to Bromsgrive and back when I had to go there to do a job.

Purrs like a kitten now so if you have a fair trip coming up then use that to see if it rectifies the problem but don't go throwing money ate parts you will probably not need.

Not many have cured the problem but I suspect that like me they were using the car for localised runs and not giving it a chance. However, I certainly would suggest cleaning your EGR anyway.

Keith

 

[BlackC55]

Very likely to be an injector missfire.

Needs to go on a Star to check the smooth engine running to see which injector is causing it.

 

[Pillabenz]

Good luck on solving the problem as it seems to be a common fault. I spent over £600.00 on parts for mine because people said it was this, that or the other . Even Mercedes couldn't solve the problem or even find one.

I put my STAR on it and no faults at all.

Cured it last weekend when I gave it a good blast from Cardiff to Bromsgrive and back when I had to go there to do a job.

Purrs like a kitten now so if you have a fair trip coming up then use that to see if it rectifies the problem but don't go throwing money ate parts you will probably not need.

Not many have cured the problem but I suspect that like me they were using the car for localised runs and not giving it a chance. However, I certainly would suggest cleaning your EGR anyway.

Keith

Ok Keith, thankyou for the reply.

 

[BlackC55]

Before you do that. Put some injector cleaner in the tank and some vpower diesel and drive it hard. Plenty of RPM.

 

[Pillabenz]

Very likely to be an injector missfire.

Needs to go on a Star to check the smooth engine running to see which injector is causing it.

I see, do you think a dose of injector cleaner would make any difference, would like to try all avenues before seeing any specialists. Cheers.

 

[Pillabenz]

Before you do that. Put some injector cleaner in the tank and some vpower diesel and drive it hard. Plenty of RPM.

Hah, just what i was typing out! Ok will do. Cheers for that.

 

[Pendragon]

Before you do that. Put some injector cleaner in the tank and some vpower diesel and drive it hard. Plenty of RPM.

Yep, totally agree with that. It took a 200 mile blast up the M4 & M5 and back to sort it. Just wish I had done that 1st before spending a fortune on parts I didn't need but hey, at least I have a bundle of spares should I need them lol

Keith

 

[Pillabenz]

Ok thanks guys, will report back in a week or two, I started it this morning and it ticks over perfect, its when it gets warm that it idles slightly low, bit strange as its usually the other way round, (poor when cold, good when warm)

 

[Agwarn]

Can't beat an Italian service!

 

[Dieselman]

Are the engine mounts OK?

The ECU should perform a cylinder balance after 30s of running so unless the injectors are faulty, it should running smoothly and maybe just transmitting idle shudder.

 

[htavs]

Get yourself a cheap diagnostic tool one that shows stored codes and pending codes. This will give you a pointer to where the problem is. My guess and that's all it is from what I have read in your thread is that your car has a vacuum leek somewhere. These cars have umpteen sensors all working within certain tolerances. What I believe is happening is when the engine is returning back to rest (idle speed) its getting misinformation from a sensor like its been told it needs more air or more fuel etc. What often happens with heat from the engine is pipe dry up or pipes chafe against things and over a period of time the split which makes the sensors go mad hence the erratic idle.

When you tap the gas the car goes back between the tolerances and it seems fine.

Do a good visual check for any split pipes first place I would look, The Cheap diagnostic tool will guide you in the right direction.

 

[xkillz]

Try using injector cleaner and fuel treatment I also used engine flush had the same problem the injectors are dirty if you do not clean them you block completely and no products will work and spend £1000+ on new injectors it happened to two of my cars the w211 needed new injectors because was completely blocked and w251 had idle issue injector clean engine flush and fuel treatment worked and no longer have the issue