just bought a 1998 impreza turbo and love it! the car runs great but has a problem when idleing. when the cars first turned on it idles no problem but after a run it jumps between aboot 2000 revs down to nearly zero, nearly stalling itself.

has anybody got an idea what this could be? any help would be grateful.

cheers.

 

MAF? you can test it by disconnecting it whilst the car is running and it should stall ( but this is by no means a definate test).
I think the only real way is to test the voltage.

Idle control valve may be another possibilty.

There are quite a few other things that can cause dodgy idle such as airleaks,other sensors playing up.

 

test the maf as said above, ICV is a possibilty, take if off & clean it or replace

last thing i can think of is crank sensor? knackered, or reading wrong?

got any fault codes or is the CEL on?

 

I had this problem with mine not so long ago and the rubber seal on the ICV was fubard and also the inlet manifold was not bolted down tight enough so had an airleak.

 

thnks for the comments. what actually is a MAF?

 

Mass Air Flow sensor it's connected to your airbox/induction kit and has an electrical connector

 

try inside the idle control valve if u have had any work done at scooby clinic as they stick it down with with silicone and it stops the idle valve from moving inside

 

the car has a dump valve on it dont know if this will have anything to do with it??
mayb not fitted properly??

 

checked the maf today by disconnecting it and it did stall. will try the idle control valve next and se if it is that.
how would i go about cleaning the valve out?