ML320 CDI excessively high idle

[Flythomas]

Hi Everyone,
Been away from the forum for a while, but still having problems with the ML320 CDI !! Starts well, and idles at 700 rpm. As soon as you engage "Drive" the rpm increases to 1400 rpm and stays there until engine is at normal operating temp. This results in a vehicle that is hard to stop, and harsh down changes for the first 3 miles or so. Local Merc dealer has been really helpful, and just replaced the ECU to cure the problem. No luck unfortunately !! However, the problem only occurs when the outside air temp is 10 degrees celcius or below. Above that it behaves faultlessly. Hoping someone out there might have some helpful suggestions..........Best regards

 

[television]

Surely this has to be a temp sender fault, easy to check by removing the wire or grounding

 

[Flythomas]

Hi Malcolm,

Thanks for the reply. Could you tell me where the sensor is located, and I will do as you suggest. If I ground it, should that repeat the fault, or will it work OK? With the warm weather, I will struggle to get down to 10 degrees for a test.

Otherwise, I will tell the dealer what you have said, and I am sure they will try a new sensor.

Thanks again for your help, I am determined to fix it !!

Best regards

Bruce

 

[television]

I see that this new engine has different technology in this area, see what I can find out

 

[dazren]

I've got a 2006 M/Y ML320CDi, with exactly the same problem as the OP. Cold weather, select D, idling rises to 1400pm, bad downchanges, engine pulling against the brakes, until engine is at normal operating temp.

So far we've had the fuel rail/sensor replaced and the problem is back.

Has anyone solved this problem?

 

[Alex Crow]

We had the same fault reported more recently on the forum, and was attributed to an electronic throttle pedal issue.

When the pedal was changed, the fault was resolved - quite common apparently.

 

[dazren]

Thanks Alex. Your post prompted me to do a search and found this thread:

http://forums.mercedesclub.org.uk/showthread.php?t=94207&highlight=throttle+pedal&page=2

Will book the car in.

 

[Tom-B]

Thanks Alex. Your post prompted me to do a search and found this thread:

http://forums.mercedesclub.org.uk/showthread.php?t=94207&highlight=throttle+pedal&page=2

Will book the car in.

I appreciate this is an old thread, but has changing the pedal solved the problem?

 

[Steve@Avantgarde]

Best of luck trying to get an answer to that question!

But if you are experiencing the same fault then I would suggest you too would need a new throttle pedal. Its a common problem.

 

[Tom-B]

It seems it’s also the throttle pedal for me too.... lifted it with my toe during high idle and tadaaa problem solved!