Low idle when cold, high idle when warm!

[mammoo]

Hi all. I've got a strange problem on my 93 rev 2 turbo and it's been like this since I bought it. When you first turn the car on it will idle at low revs - around 800rpm. If it's cold then this causes the engine to struggle and sometimes die, I need to give it some revs for a couple of minutes to get it warmed up enough to keep going on its own. Then, as the engine warms up, the idle speed slowly increases until it gets to about 1,200rpm when fully warm. The idle speed is basically doing the exact opposite of what it should be doing, 800rpm when cold and 1,200rpm when warm instead of 1,200rpm when cold and 800rpm when warm.

The ISCV has been thoroughly cleaned out but it wasn't particularly dirty to begin with and there are no faults displayed. Does anyone have any suggestions for what could be causing this?

[SonicSW20]

Have you checked the operation of the ISCV? There's a diagram in the BGB. You can applt a voltage to the pins and watch the valve move.

[mammoo]

No I've not tried that. I'll give it a try asap.

I've read other people will similar problems were related to the ecu water temp sensor so I might try changing that as well.

Any other suggestions would be appreciated - I've seen a few people who ended up changing a lot of bits to try and get to the solution!

[mammoo]

My garage has now checked the operation of the ISCV and it's working fine. They also replaced the ECU coolant temp sensor but the problem remains. We've both checked all over for any vacuum leaks and we can't find any.

Anyone else have any suggestions?

Does anyone know anyone in Yorkshire who can run proper diagnostics on them to see if its a dodgy sensor somewhere?