Sadgrandad

93 WRX

1) Can anyone explain (to Mickey Mouse) how the idle air solenoid works and what its function is, please?

2) When I take the cap off mine, the spindle/plunger thing can only be turned through about 90 degrees and lifted or depressed a few mm, is this normal?

3) I keep getting an intermittent e/c 23 (i.a. solenoid) but it often only lights for a few seconds and seems to go off when I depress the clutch. The light does not seem related to any immediate change in performance. If there is a fault, should the light stay on or should it come on next time the car is started?

Pleeeeeeeeeeeeeeeeeease heeeeeeeeeeeeelp!

Sadgrandad

Pretty please

tweenierob

1. The idle valve is controlled by the ecu, on top of the ISCV is a solenoid which rotates 90degrees left to right. Inside the ISCV is a shaft with a paddle on it, this shaft also turns 90degrees left to right...
The paddle's use is to allow air to enter the inlet manifold/engine whilst the throttle butterfly is closed (idle) with the shaft fully clockwise the paddle is closed and any air entering the manifold can oly do so via the throttle butterfly (ie. whilst accelerating). When the car is idling (throttle closed) the engine would be starved of air and would cut out, this is the ISCV's Job. The MAF sensor (Airflow sensor) senses how much air is entering the engine and the ecu adjusts the ISCV accordingly.
On cold start (for example) the ISCV will be fully open as more air/fuel is needed on cold start, whereas on warm idle the ISCV may only be half open.
2. yes this is normal, but you may need to lubricate it with some WD40.. (see 3.)
3. As JGM stated, teh CEL only illuminates when there is a problem, if the problem is intermittent the light will only illuminate when teh problem is actually happening. Your ISCV (idle stability control valve) may be sticking occaisionally, this in turn will give CEL, the reason for this is because the ECU will be telling the ISCV to adjust airflow, but as it is stuck it will not adjust... The MAF will sense that the airflow is not changing and give CEL for the solenoid.
I suggest taking the solenoid off again and sparying WD40 onto teh shaft and inside the slot for the shaft on the solenoid.

Rob

Bit long winded, but its a start to your q's

Sadgrandad

Thanks very much, Rob. Why would this throw a CEL when the car is motoring, if it's only to do with idling? Sorry if I seem thick.
Rod

pugoetru

because every time you change gear the idle switch tells the ecu the engine is idling





then its not

tweenierob

No worries mate!!

Shouldnt do... But if the ISCV is stuck open it will.

Rob