hostagewrx

On my WRX MY94 the engine check light is on and when i have tested to see what the fault is, it indicates its the idle switch, this seems right as the engine does idle abit to roughly!

Anyone got any ideas how i can check the unit out or what i should be looking for?

Cheers

STI5300

iTrader: (4)

I had the same problem on my RA, I found the wires that feed into the ECU from the wiring diagram and checked the resistance anainst that given in the workshop manual. The switch is a sod to adjust as it is very close to the inlet but once rotated to give the correct value it was ok. 1/2 an hour at the most

Dark Blue Mark

Ok, is is the ISCV (Idle speed control valve) or TPS (throttle position sensor).

The one with a switch is the TPS and is mounted on the throttle body. It give a 0-5 v output and they generally fail rather than need adjusting. The ISCV is mounted down from the intercooler and has a plastic lid on it. Its held in by 2 bolts and can be adjusted left to right to increase / decrease the idle speed.

On another point, the fault code you see may actually be the result of another failed sensor, just to confuse you more! For example, I have heard of a faulty lambda sensor (which can cause idle probs) throw up a TPS fault as the tps thinks it is misreding.

MB