I have an Idle problem.

LilTimmy

With engine running, out of cold loop, I turn on the lights idle drops to, say from 850RPMs to 600RPMs and doesnt recover unless you turn off the lights, and if you turn on the heater fan also at the same time, RPMs drop to 3-400 RPMs, just hardley running. I also driving about come to a stop, and the engine idles down to 600 RPMs. Ive replaced Idle air control valve, the old one was worn out, new fuel pump, and fuel regulator on top of the TBI, I thought about the MAP sensor, but I dont want to buy things that really arnt worn out or broken, if you get my drift? Any clues? Help!

LilTimmy

Thank you Mr. Shiftright! I bit the bullet, bought another Alternater, I always have been skeptical about this alternater just because of the noise it made ( not having any better sence to realize that someting was wrong with it) but that cured the problems, no more noise, idles just fine with the lights on and fan! Great! Thanks for the encouragement and a little push in the right direction.

LilTimmy

I also did'nt mention, my Geo is a Canadian model, no EGR and all of that sort of stuff.

Mr_Shiftright

I would load test your battery and alternator output.

LilTimmy

Thank you, Alt 14., batt. good

Mr_Shiftright

I wonder if your belt is slipping? It seems that if idle drops with headlights on, there is some underperformance on the alternator, or a very heavy draw on the alternator. I would persist in that direction of inquiry.

LilTimmy

O.K. I checked alt. and batt. load. Alt.14.26 at idle no lites or heater fan, 13.8 with lites and fan on, 14.2 with lites and fan on, at about 950-1000 RPM. Batt. tested good13.7v. Now one thing, about this Alt. ever since I put it in, it has always whined as if it were under load or not turning fast enough, it was a replacement for the original alt. cause they did'nt have the exact replacement, is this a possibility of my problem?

Mr_Shiftright

I don't know the rating of that replacement alternator. You can calculate the amperage you should need by using this chart:

http://www.qualitypowerauto.com/pages/AmperageLoadCalculator.php

I suppose that a bad bearing in the alternator could cause excessive draw on the engine itself. I think I remember that normally an alternator under load consumes something like 7-8 horsepower.

Did you check alternator belt deflection. If you push on the belt, it should move no more than about 13mm.

LilTimmy

the alt. was constantley under load, I guess the reg. in the alt was in a full draw mode, if that makes any sence, for a lack of better term. and no the belt was fine, the bearings were fine, just the reg. I figure.

Mr_Shiftright

So everything's working now?