Car is Vauxhall Vectra 2.5L V6 1998 S reg (X25XE engine)
Can anyone verify where the idle control valve is? Is it the black plastic component mounted on top of the inlet manifold over the rear bank of cylinders, just in front of the square plastic box? Secured by two torx screws and has a 2-pin electrical connector on the left hand side.
The reason I am asking is a couple of months back the engine revs dropped right down and died when waiting at a junction. A day or so later when sitting idling the engine speed started to become erratic then climbed to 1500 - 2000 rpm or so. I switched the engine off, restarted, and everything was ok. Just recently the engine decided it was going to idle at 1500 rpm that day. A sharp blip of the throttle would not alter it. On the way down the revs would drop to about 800 rpm but something immediately pulled the speed back up to 1500 rpm. Now it won't idle at all. The car drives ok but come up to a junction and it needs constant throttle to keep the revs above 2000 rpm to prevent it from dying. Incidentally, the engine management light has not come on during any of this.
A search on the net indicates this is a common problem usually caused by the Idle Control Valve getting gummed up. Often cured by removing the valve and cleaning with carburettor cleaner. Trouble is, none of the pictures I have seen show a valve that I recognize on this engine. The Haynes manual for the Vectra does not cover the X25XE engine. It just refers to the Omega manual which appears to have yet a different valve. Hence the need to ask someone who knows.
Thanks MW