850 Idle Issue

[grumpysteve]

Hi Chaps, I have an issue with the idle on my 850 (2.5 10v auto), its idling high at 1500-1600 rpm. Tends to be when its warmed up but does not happen all the time, so if I'm stopped in traffic in drive the idle is high (1100 ish), if i put it in neutral it goes up to 1500. Sometimes putting it in neutral the idle goes up and then down to the normal level! Its recently been serviced and the mot has just been done with no issues. Anyone else had this or any ideas what the problem might be? Any help appreciated!

GS

[morgrp]

could be(or i'd check the) Idle control valve, purge valve or throttle position sensor - Purge valve faults are common as muck on 850's - piss to change and cheap too - when they bugger up they tend to raise the revs between gear changes - is it a 10 or 20 valve engine?

[grumpysteve]

Thanks for reply. Its a 10v engine and an auto(done 126k). It doesn't rev up between gearchanges, but does when the car is stationary or in traffic. Also occasionally while driving it can feel like the throttle is open even though I am hardly pressing the accelerator, if that makes any sense!
I initially thought it may be some sort of idle control valve - but where abouts is it?

Thanks

GS

[morgrp]

It's situated near the throttle boy on the front right hand side of the engine bay:


Its the black circular item with a hose at each end and an electrical plug

The 10v engine has a Siemens injection system rather than a bosch - Buy a second hand one to replace - make sure its the right one though - piss to replace - Once replaced start the car and don't touch the throttle. The ECU will need to adjust itself to the new valve - you may hear it hunt around for a minute or two - this is normal.