I've had an unstable idle problem on my Type R for many months. I've changed lots of the obvious stuff, but to no avail.

Basically, rather than staying at a fixed speed the engine revs cycle between about 800 and 1100rpm. It's only an intermittent problem. Much of the time the idle is stable. Sometimes the idle is not held high enough and the revs drop and the engine is very lumpy and can stall, but usually it picks up again.

Could this be anything to do with the neutral position switch, or can I discount it? Throttle position sensor is the other one I'm thinking about.

For info, I've already changed:
Plugs
HT leads
MAF
O2 sensor
Crankshaft position sensor
Camshaft position sensor
Coil pack
Dump valve (back to recirc)

I've tested the ISCV but it turns okay and the resistance is correct.



Any other ideas?

 

It sounds like you have the same problem as I have with my MY93. It only happens if I havn't used the car for a few days, and disappears once it has warmed up. I have been advised to clean the ISCV, but I havn't tried yet.

 

Actually, mine does it at any engine temperature. I've cleaned my ISCV thoroughly.

Thanks though.

 

Any resolution to this problem?