Idle Stabilization Valve - Advice please

Ringmaster · 28-07-16, 10:24 PM

Greetings all,

If I replace the ISV on my engine, can I simply fit it without the need for equipment to adjust the idle setting? A straight swap of new for old.....

I have a KU 5 pot on my C3.

Roger Galvin · 29-07-16, 11:19 AM

That depends on whether anyone has messed with the engine while the ISV has been in a defective condition. Commonly as they fail the revs tend to run gradually higher and the user screws in the idle screw to reduce the air being allowed to bypass the throttle butterfly, once they have it all the way in they start messing with the mixture screw leaning it off to reduce the RPM.

Fit a new one and see what happens. Ideally it should run with 430 milliamps throught the ISV at 820 rpm and a mixture in the order of 1% CO.

AdrianH · 29-07-16, 01:05 PM

You make it sound so easy Roger...

29-07-16, 11:19 AM	#2
Roger Galvin Grown up member Classic Audi Club Member Join Date: Feb 2011 Posts: 239	That depends on whether anyone has messed with the engine while the ISV has been in a defective condition. Commonly as they fail the revs tend to run gradually higher and the user screws in the idle screw to reduce the air being allowed to bypass the throttle butterfly, once they have it all the way in they start messing with the mixture screw leaning it off to reduce the RPM. Fit a new one and see what happens. Ideally it should run with 430 milliamps throught the ISV at 820 rpm and a mixture in the order of 1% CO. __________________ Roger Galvin Chairman & Technical Secretary, qOC quattro Workshop

29-07-16, 01:05 PM	#3
AdrianH Grown up member Join Date: Jan 2014 Posts: 218	You make it sound so easy Roger...