Idle Control Advice

[MarkMc]

Some information for everyone.

First thing that must be burnt into your brain. IDLE CONTROL IS NOT A FUNCTION DESIGNED TO SMOOTH OUT A ROUGH IDLE. IF THE ENGINE DOES NOT IDLE SMOOTHLY WITH IDLE CONTROL SWITCHED OFF THEN SWITCHING IDLE CONTROL ON WILL GENERALLY MAKE THINGS WORSE.

Idle control is designed to help maintain a set idle RPM when extra load is placed on the engine by things like air conditioning, power steering, alternator load when turing on headlights, etc. Also it is used to hold idle speed a bit higher when the engine is dead cold.

It is very important to get the fuel and ignition table sorted out at idle before attempting to use idle control. I see so many people who have an engine yet to be tuned with the idle control turned on and wondering why the engine stalls, hunts and is generally unhappy.

Turn the idle control off, get the engine hot, set the base idle air (either butterfly position or idle bypass screw or DBW Translation Table) and sort out the fueling and ignition until the engine is idling smoothly.

For engines with big cams you can either raise the base idle speed or live with the fact that it has a rough idle. You can always just use the idle valve to bump up the idle speed when the engine is cold.

[bbs16]

Am using a 3 wire bosch idle control valve with an M4 unit. How can I use the valve to up the idle slightly when it is cold?
Thanks Andy.