940 rising idle

Hi I have got a 1994 940s 2.0. I have a problem in that after driving for a
while my idle speed increases from ~600 rpm to @1000 and then to 1500. If I
stop the engine at that point and then imediately restart the motor it idles at
600 rpm again. Any ideas on why this is happening?
Andy

 

Do you do any regular preventive maintenance on your car? I would suggest that
every two years you thoroughly clean the inlet tract including the Idle Air
Control Valve (which is probably why your idle is going haywire). Use fuel
system/fuel injector cleaner every fifth fill-up. Clean the PCV system tubing
and filter (filter is not fitted on turbo models). Take especial care when
cleaning AMM unit as it is easily damaged. Make sure that all connections
between engine and fuel computer/ignition computer are making good contact and
that the ignition power module is working OK with all earths correctly earthed.

Most of these techniques are available in the Haynes manual for your car.

Cheers, Peter.

: Hi I have got a 1994 940s 2.0. I have a problem in that after driving for a
: while my idle speed increases from ~600 rpm to @1000 and then to 1500. If I
: stop the engine at that point and then imediately restart the motor it idles
at
: 600 rpm again. Any ideas on why this is happening?
: Andy