RPM idle - How low is too low?

[OptimusPrimeSr]

Setting the idle...

how low is too low?
what are the ramifications of a lower/higher idle?

was having eratic idle, went through all parts, coolant, IAC, EGR, FIT, AirBoost, etc...lowered my idle from 900 to 600 and its gone.

[HA91]

i think it is supposed to be 800 rpm

[BlackMagicCB7]

Around 750 to 800 rpm is teh lowest. You should have it between 900 -1000 rpms....

[MyCord]

I've always thought it was supposed to idle at 650 my car usually idles at 550-650

[cb7Choler]

lowest is 650.... highest is 1,000... most all cars idle around 800 to 900.... so give or take whatever go around 800 to 900 rpm....

[OptimusPrimeSr]

now that we have everyone's educated opinion, could I get a little justification or knowledge behind the scenes?

what are the ramifications of a lower/higher idle?


fwiw, I'm probably going to bring mine up to 650-700...I like the low idle.

[MadSpleen85]

I over adjusted mine a while back and I almost lost power everytime I stopped. I dont recall what RPM I was running at Idle but the lights dimmed, and the engine seemed to almost spudder to a halt when I got on the brakes. Later

[Otto]

Its on the emissions sticker on the underside of the hood. No guessing there.

550+/-50 with IACV bypassed, 750+/-50 with IACV connected.

Mines right at 750 according to my portable tach.

edit:my bad...its 700+/-50 with the IACV connected.

[NAiL05]

650-750 is about right for our stock vehicle specification. When its too low you will know the car will try to stay on and keep on wanting to cut off.

[TypeG]

to be honest, the idle shouldn't be adjusted as it's set from the factory. they even put a dab of thread lock to keep it from moving around. if the car doesn't idle right, it's not the idle screw, it's some other problem. later.

[jova1993cb]

vaccume leaks will cause this too pain in the ass to track down too. see if there might be a leak somewhere. get a mechanics stethoscope. makes tracking the leaks easier.

[Otto]

to be honest, the idle shouldn't be adjusted as it's set from the factory. they even put a dab of thread lock to keep it from moving around. if the car doesn't idle right, it's not the idle screw, it's some other problem. later.

True...better to fix what's causing the bad idle, then adjusting to compensate. Unless engine mods warrant it, of course.
Mine did need a slight adjustment, but it had never been adjust before then, and probably won't need to be adjusted again.

[jova1993cb]

yea, but with everything on our cbs it is a biotch to find the problems

[accordaffair]

lower idle - less fuel usage

higher idle - less vibration at stop lights(mostly auto users would be concerned about this)

[DFRHonda]

vaccume leaks will cause this too pain in the ass to track down too. see if there might be a leak somewhere. get a mechanics stethoscope. makes tracking the leaks easier.

Actually, tracking a vaccum leak is not hard to find, best trick is using propane with a nozzle, turn it on just enough to where it flows out of the tip(you will see the gas coming out of it). Take that and run it along your vaccum lines, once you hear your car idle faster, you have pinpointed the "leak" (hole). I've done this to many cars when I was in high school fixing other peoples cars that had a problem with their vaccum lines, and it has worked every time to know which line needs to be replaced.