rotary idle actuator

[chilled]

hi all

i have a 1991 300e that stalls when i stop at junctions etc
it only happens when the engine is up to temperature
it idles at about 750 rpm in park but drops down to 500 rpm when in gear
i removed the idle actuator and found that the valve does not fully shut is this correct
should there be voltage to the actuator all the time the engine is running
i found that if i unplug it the engine stalls
it as the bosh ke jetronic injection system
is there a way to adjust the idle speed

if anyone can suggest other parts that may be causing the above and tests to carry out i would appreciate it

thanks in advance

chilled

 

[Dieselman]

Firstly check there isn't a misfire due to an HT lead or spark plug.
The actuator valve woon't fully shut as it acts as the idle bypass. There should be some power to it all the time IIRC.

The idle either isn't adjustable or there is a bypass screw in the side of the throttle body.
If the engine revs to fast idle when cold then the idle valve is working. It sounds like you may have an air leak which will always be moree pronounced once the engine is warm and the idle valve closes more.

 

[chilled]

thanks for the reply dieselman
will start checking for leaks at the weekend

cheers chilled

 

[chilled]

hi again

been looking for leaks as dieselman suggested
there seems to be a leak on the hose from the rotary idle to the inlet manifold
the leak appears to be below what i think is the cold start valve
does this valve fit into the hose and is there a easy way to change the hose

thanks in advance

chilled