W124 Idles between 1500-2000rpm

[rumelk]

Hey Guys & Girls,

Got a bit of an issue with the 124. When i start it up, it constantly idles around the 1500-2000rpm. It started doing it very randomly, it use to idle between 700-1000rpm, which is what i thought was normal. However all of a sudden it just crept up to 1500-2000rpm.

The idle is not rough, but it car drive it self. I went down a straight road and it managed to accelerate to almost 30mpg without me even pressing the pedal. I did recently check the duo valve, so radiator pipes were taken out, could there be any sort of air leak which could have caused this.

Ive also checked the throttle linkage springs which seems ok, is there anything else i should be looking for?

Thanks

 

[khimani_mohiki]

check your OVP relay

 

[Pottering]

I've had a similar issue with a 1994 E320. OVP change didn't help, changed cruise/idle ecu but same result and I'll be changing the throttle body in a couple of weeks, which I've got my fingers crossed will fix things. Will report back when it's done.

 

[vincenz]

Mine seems to do this, however what i find sometimes is it does it at the lights after driving, i sometimes find the matt has shifted forward and is resting on the accelerator pedal, when you pull it back into position it goes away, i need to get some velcro or something to hold it in position.

 

[rumelk]

check your OVP relay

where can this be found? and what am i checking for?

 

[grober]

Try cleaning the throat of the throttle body carefully with solvent. It can get dirty and cause problems by not letting the throttle plate close properly.
edit that's if its a twin cam engine. If its an earlier single cam engine then the throttle bypass unit may be jamming open. They can also be cleaned with solvent but if the heated bimetal strip is gone the unit may need replacing

 

[rumelk]

checked the ovp relay and still nothing. how do i find the throttle bypass unit?

 

[grober]

checked the ovp relay and still nothing. how do i find the throttle bypass unit?

What is the exact age of your car please? Has it got the older single cam M102 engine? Is it fuel injection rather than carburettor? You will have to remove the air cleaner assembly to see the relevant rubber pipework associated with the bypass idle regulator. çàï÷àñòè Mercedes: êîäû çàï÷àñòåé ìåðñåäåñ

 

[rumelk]

What is the exact age of your car please? Has it got the older single cam M102 engine? Is it fuel injection rather than carburettor? You will have to remove the air cleaner assembly to see the relevant rubber pipework associated with the bypass idle regulator. çàï÷àñòè Mercedes: êîäû çàï÷àñòåé ìåðñåäåñ

i think the engine is a m111.940 the 1998cc version. I done a little digging around and this fits the spec of my engine.
Mercedes-Benz M111 engine - Wikipedia, the free encyclopedia

 

[grober]

Right then it doesn't have a bypass throttle unit. Have you cleaned the throttle body throat internally [carefully]with solvent together with the butterfly flap yet?

 

[rumelk]

Right then it doesn't have a bypass throttle unit. Have you cleaned the throttle body throat internally [carefully]with solvent together with the butterfly flap yet?

No. Where is that?

Many Thanks

 

[grober]

item 80 here çàï÷àñòè Mercedes: êîäû çàï÷àñòåé ìåðñåäåñ