G60 high idle/revving itself

[Hoppum 0]

A few weeks ago my G60 started idling at about 1800rpm after a few minutes of driving and then a week or so after started revving itself between 1600 and 1900 continuously, again after a few minutes of driving.

 

Firstly I cleaned the ISV which was pretty dirty but when I refitted it the car started revving itself between 1000 and 1300 immediately on start up and was very jerky to drive. Thinking that the ISV was knackered I fitted one from a KR engine which didn't solve the problem either (the G60 ISV also works fine on the KR engine).

 

I then ordered a new blue water temp sensor but while I was waiting for it to arrive at the stealers the car (still with the KR ISV) started sticking at 1500 on idle and eventually dropping to about 1050 if I was stationary long enough. When the sensor arrived I replaced it anyway and things remained unchanged. Then on the way to work this morning the engine started revving itself between 1600 and 1900 again! It did the same on the way home.

 

So currently the car idles fine at 1050 on start up but after a few minutes driving starts sticking at 1500 then slowly dropping and then after a few minutes more starts revving itself between 1600 and 1900. The only other problem with the car currently is a blowing exhaust.

 

Any help would be greatly appreciated as this doing my head in as I look like some moron revving his engine every time I stop at a roundabout/junction (which is a lot in Milton Keynes) and the MOT is next month and I can imagine this failing it.

[mimjed 0]

check throttle cable and butterfly valve on throttle body, but im sure you have already.

 

getting a smoke test is helpful to spot any leaks.

 

when mine was idling high and revving itself it was the inlet mani gasket. i hated looking like a gimp at the lights too.

 

good luck.