High idle speed?!

[dajm1]

Hi, for some reason the Cerb has started playing up? When you first start it it idles fine (900ish) but it seems as it gets warmer the idle speed gradually goes up to about 2000 rpm! Driven it miles but the idle speed won't drop. Checked on computer and everything is reading as it should.
Any ideas?

[Tanguero]

If the throttle readings are the same as when it is idling at 900 when cold, then the only thing that I can think of is an air leak. If its leaking somewhere that expands as it gets hot thus opening up a leak that might explain it.

If it was a 4.2 I would say check the bolts that hold the intake manifold and thermal insulator to the head, but I don't know what the 4.5 arrangement is.

[dajm1]

Hi, It's a 4.5. Any idea of the throttle opening % at idle on the 4.5, mines set at about 18% just read that thats for the 4.2 not the 4.5?

[Tanguero]

I believe its the same for both