high idle speed

[teddymac]

hello, new to the forums, have a quick question.

I have a 1990 200E which when warm idles at 1200-1300 rpm and wont come down. and is sometimes difficult to start. have replaced plugs, new leads, and cleaned the carb housing with carb cleaner. Any help gratefully appreciated!

 

[sheff1972]

check the throttle linkage there should be a micro switch , this is the idle speed contact , it has 3 wires , it may not be going fully home

 

[Dieselman]

It's possibly the auxillary air valve is stuck or there is a vacuum leak or the throttle return spring is broken.

 

[television]

I think it is the thottle switch and the car is running off the main ECU in the fail safe mode.

By putting an ohm metter on the contacts its easy to see if the switch is closing at Idle