C220 CDI rough idling

[Chopper]

Have '02 c220 cdi with 75k on clock.When I cold start there is a fluctuation on the idle rpm as if it misses a beat ! Seems fine when warm and no smoke problems . Have changed Fuel filter and put some injector cleaner in today so not sure how that will work.

Any ideas??

 

[D3Less]

Have you checked / cleaned the MAF?
There is a very good thread on it here.

 

[Chopper]

I have read the thread thanks ,seems to be mixed reviews on doing it or not.
What does MAF stand for ?

 

[television]

I have read the thread thanks ,seems to be mixed reviews on doing it or not.
What does MAF stand for ?

The EGR valve is the most likely ifs its ok at naonmal running

Malcolm

 

[television]

Sorry MAF = Mass air filter

malcolm

 

[Uncle Benz]

Is there any smoke from exhaust? If it only happens at cold start and clears after about 30 secs I would have a look at glowplugs. Maybe one of them is getting weak.

 

[Chopper]

thanks malcolm ,whats involved in checking that out ? what does it stand for ?

 

[Chopper]

No it can last up to 20 min after start Uncle Benz ,seems to clear after that.Still good acceleration and power !

 

[television]

EGR valve is the Exhaust recirculation valve. it returns harmful gasses back to the intake when cruising. after 60k + miles they can stick partly open,this causes rough idle.

Malcolm

 

[Chopper]

Thanks ,is it major surgery to release it or unstick it ? How does one go about that ?

 

[television]

Thanks ,is it major surgery to release it or unstick it ? How does one go about that ?

Some people clean them,but it is a waste of time as the spring is weak, the trade always change them.

You could always take it off to see if it is stuck open a little.


malcolm

 

[Chopper]

Some people clean them,but it is a waste of time as the spring is weak, the trade always change them.

You could always take it off to see if it is stuck open a little.


malcolm

Is that a difficult job Malcolm ,where exactly is it on engine ?

 

[Chopper]

Used some diesel fuel treatment and changed fuel supplier and all running sweet again. Started with the cheapest option and it worked !

 

[James100474]

Malcom is correct as always! Had this problem a short time ago with my C 270, cleaned the MAF, used diesel treatment and cleaned the EGR valve. But , no fix. Turns out EGR valve was struck open. Fitted a second hand EGR valve and it's been running perfectly since.

 

[Marxs1]

Hi,
I had changed my glow plugs some time ago, however as the cold of winter approached the car had the rough starts and shakes. I re investigated as I thought it maybe the relay, when I checked if power was getting to the glow plugs there was none. Pulled the relay apart thinking it would be the fusible links, however they were good. After much messing around it was an earth wire near the brake booster that had either been chewed by a mouse or just broken.
I cut the earth wire Brown/White near the connection to the glow plug relay and screwed it to the chassie. Low and behold for the first time since I've had the car I get normal starts when cold and all glow plugs working. Hope this helps someone else.
Cheers.

 

[Marxs1]

I must add it was the earth wire that runs from the Glow plug relay that was the problem.
Cheers

 

[patxi]

I've got some before and after photos of my EGR somewhere, but not with me now. You also need to release the little plastic tags and ease the cover off to get all the crud out from inside.

Many people struggle to get the EGR out, you need to knock it back and forth (gently) using a a hammer and old screwdriver, see http://forums.mercedesclub.org.uk/showthread.php?t=122368