razzele

I have a rough idle when the engine is warm. I've cleaned out the IACV thingy on the side of the inlet manifold and it hasn't improved.

When I unclip the wiring to the IACV the idle speed raises to 1200 and steadily stays there, effectively solving the rough idle.

Any idea on why this is happening? Is it ok to leave the car running with this disconnected?


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MB

Removing it will possibly leave it fully open and send a fair bit too much air into the manifold, thus it will idle high. The valve itself acts as a variable restriction.

I'd find the root of your issue, and put the ISCV back on.

razzele

I'm wondering if the valve itself is at fault.




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MB

Being subject to 2 bar boost all the time probably doesn't help

Rare they totally go bad though, normally just need a clean.

s2konroids

What ecu are you running could be a few things? Wrong injector dead time, idle settings etc etc as you'll be running bigger injectors.

Or was it running okay beforehand?

simonix

I had the same problem and it turned out that the throttle body had crud at the bottom and wasn't allowing the butterfly to shut completely when at idle and this then confused the IACV and the MAP sensor, etc. The fact that it still idles high when you disconnect the sensor could show that the throttle is still open slightly because of this.

A good clean with some brake cleaner and it was sorted on mine. Worth a check?!

oxhouser

my car used to stall at junctions, i cleaned the ICV and the problem went away for a month but returned just as bad, ended up getting a 2nd hand ICV from a brakers yard for £40, that fixed it.

razzele

Im sure ive got another iacv in the garage somewhere but that would mean tidying it!

I think ill just leave it unplugged for the mean time.