Holding revs

[rwb]

I've been trying to investigate my latest noise (I'm pretty certain it's the air con compressor).

The noise is most noticeable at 1300RPM. But it's really difficult to hold 1300RPM. Push the accelerator down a tiny bit and it goes shooting up to 2000, then easing off to bring it back down I have to move a long way before anything happens, then over-shoot 1300 in the other direction (and hear the noise as it passes).

Are they all like this?

I don't think its the throttle position sensor, as I'm now on my third -- although it is second hand.
What else could it be?

While I'm at it: there is effectively slack on the accelerator cable, but adjusting it up on the TPS results in engine anti-pollution system defective, presumably because the TPS isn't sending zero when the ECU thinks it ought to be. Again: are they all like this?

Ta,
rwb.

[Doggy]

Mine is more or less the same - can't get 1300 without overshooting to say 1600, but can almost hold it steady by letting it slow gradually back to tickover.

I think it's normal behaviour, your turbo is just starting to make a difference as you pass 1200 RPM or so. It's less pronounced on mine, (but I've got a vnt turbo).

[rwb]

...your turbo is just starting to make a difference as you pass 1200 RPM or so

good point

[Bailes1992]

I don't think your turbo will make much boost at idle because it's not under any load?
Anyway mine is exactley the same!