Crap Idle C20XE

[nova_saloon]

Ive had a naff idle its not going mad just bumps up and down on the gauge all the time from about 1,050-1,200rpm has always done it for four years. its never idled less that that, well according to the gauge anyways. Ive replaced the engine wiring loom about 3 times, rebuilt the engine twice, replaced the inlet manifold, injectors, coil pack, camshaft sensor, spark plugs, checked compression, changed air flow meter, lambda sensor and have got four spare idle control valves cause i replaced it that many times thinking it may be that and also tried multiple ECU's. all im not sure is the throttle positioning sensor has been changed or not and never changed the crankshaft sensor. Soooooo any ideas anyone? also is anyone close by with a coil pack type C20XE just to try three of four sensors with?

[Will F]

If you've changed all that and it's still doing it, then what's the common thread? Ie what has stayed the same? Vacuum hoses etc?

[nova_saloon]

Very good poing, but the vacum line that goes from any of them have all been replaced in there time indeed. trust me its annoying an i feel like ive done all i can!. i seriously want to kick it! I wish i had some sort of clue as to why its not wokring properly!

[Will F]

Does it do it when cold or warm or hot or all three?If its hot, it can be bad heat soak. If its cold or warm or any coolant related change it could be cts? It's unlikely the crank sensor as that either works or the engine won't run at all.

[Nova_Tek]

Fuel pump relay? Had crap idle, poor running, em light flashing on and off etc all done by a bad fuel pump relay.