All cars today have a number of systems that control every aspect of their operation. Years ago when all cars were carburated, the engine operation was dependent on the carburator for all fuel management. Now with fuel injection the responsibilities are computerised and taken care of by valves. One of the valves is the idle control valve. Ir is a mechanical valve and therefore subject to failure, which is a condition that is easy to recognise.
Start your car, and listen to the idle. Does it sound faster or slower than usual? Does it "stumble?" All of these things are symptoms of a failing control valve.
Locate the idle control valve on the intake. In every car they look different so refer to the repair manual of your specific car to know what it looks like.
Remove valve from the intake and clean with carburator cleaner. It will probably be covered with black varnish so some amount of cleaning will be necessary. Once clean, reinstall.
Start the car and determine if the engine's idling has improved. If the idling has not improved, you may need to replace the ICV.
ICV valves rarely need more than a cleaning and tend not to break.
Tips and warnings
- ICV valves rarely need more than a cleaning and tend not to break.
Things you need
- Carb cleaner fluid
- "BMW 3 Series (E36) Service Manual: 1992-1998 M3, 318i, 323i, 325i, 328i, Sedan, Coupe and Convertible"; Bentley Publishers; 1998
- "BMW 3 Series (E30) Service Manual: 1984, 1985, 1986, 1987, 1988, 1989, 1990 318i, 325, 325e, 325es, 325i, 325is, 325i Convertible"; Bentley Publishers; 1991
- Haynes: Jeep Wrangler Repair Manual Years 1987 to 2008