Well, my car's idle will bounce up and down ever-so slightly, but once I hold the brakes, it'll stay totally still. Also, when I press the brakes, the interior lights (if they're on) will dim a little. I suspect it's the alternator, but could it be something else?

 

Anyone?

 

You may have bad grounds. Try regrounding your battery or add additional grounds.

 

Most autoparts stores will test your alternator for free. I don't think the alternator is your problem, but if you get it tested, then you can know almost for sure.

 

When you press the brakes you load down the alternator which loads the engine, all 100% normal.

Bouncing idles all almost 99% caused by too much air entering the throttle body. Adjust down your idle, you have two easy was to do that.


Be like Nike, just do it!

 

Being that I have very very very bad luck with alternators I can tell you that I have never had the rpms fluctuate at idle... unless it died. Test your battery. If the alt is going it'll start draining your battery if it's low it's a clue your alt maybe going.

Victor

 

Yeah, but the RPMs go back to normal (don't bounce) when I put a load on it.

 

Hrm, it also seems to do it when I move the steering wheel around when the car is idle. I'm gonna add another ground and see what happens.

 

Your EL-unit (Electrical Load) will tell the ECU when you hit the brakes, and your PS pressure switch will tell it when you turn the wheel. Both of these are input parameters for the idle control function of your ECU.

 

When you hit the brakes your brake booster uses the engine's vaccum and therefore the rpm will fluctuate. When you turn on the lights it puts a load on the electrical system which will cause the idle to fluctuate but it will settle back my understanding is that it's normal on all vehicles. When you turn the wheel your using the power steering pump which is driven off of the serpentine belt so the vehicle must compensate for it.

 

I have the same problem with my car , when I start it its at a high RPM until it warms up, then sometimes it will idle but seem to bounce up then down repeatedly... this only happens sometimes I messed with the air/fuel mixture and it doesnt happen no more...no electrical problems... nothing happens when I press brakes either...Im thinking its just the air flow in your car.

 

Having some exact symptons on this as well. Also when I press brake it goes back to normal. If you find the answer Walien plz make sure you post!

 

This guy is extremely correct, your idle problem has to do with a/f, end of story.

 

vacuum leak?

 

Classic blown LIM.

...and really fun to replace!

 

haha...that would suck. But it's all easy work, well worth it, and cool to do.

 

Hrm, I dunno if it is. I've had this problem ever since the start of the rebuild.