Northstar Engines and System Technical Discussion Discussion, Please help with eratic idle!!!!!!!!!! in Cadillac Engine Technical Discussion; Hi guys, I have a 99 sts that has an eratic idle or hunting idle(up and down)after its warmed up ...
Hi guys, I have a 99 sts that has an eratic idle or hunting idle(up and down)after its warmed up and sitting in traffic. It doesnt do it when I turn on the a/c. Any help would be appreciated. Thanks, Tony.
The fix is probably to: Do a good throttlebody cleaning. Do a good EGR valve cleaning. Pull the engine cover and do a thorough search for vacuum leaks.
If turning on the A/C temporarily cures the hunting, then the problem may be an erratic ISC system: the A/C ON command also increases idle speed slightly, so that function may either move the throttle butterfly or increase idle air just enough to "cure" the problem.