Poor idle after dead battery?

Question

2003 Suburban - had no power (drained battery)... In a hurry I purchased a new battery (didn't have the alt or battery checked).

After putting in the new battery all seemed well, until I noticed the idle was very poor. The vehicle stalled when in reverse and using the power steering. I'm noticing the RPMs hover around 250-400 usually over 500 at idle. When applying the gas higher RPMs all seems fine.

I went back to parts store and had the alternator checked. It showed 13.2 volts, and 0 (zero) amps. So I installed a new alternator... The volts were now 13.8 and the amps were around 5 (still too low). So I swap the new alternator again.

I was assuming my poor idle was due to the alternator not putting out the necessary power. I'm heading back to the parts store to test yet again. Assuming I didn't get two bad alternators, what else could be causing the poor idle and low amps? Everything was fine before the battery died....

Tuner asked: My question to you is after you installed the new alternator and started the vehicle did you notice if the red battery symbol was displayed on your IPC or lower battery voltage meassage appeared on the driver information center part of the IPC.

My response: No, the info center had no messages and the battery light was not on. The only way I know the alternators were bad, was the test that showed Zero or 5 Amps....

Checked the (2nd) new alternator and it's putting out the correct Amps (around 800). The idle problem was still present at first but has seem to taper off as driving has increased. I did follow some directions to reset the idle (pull ECM fuse, then idle in drive for 2, 5 min periods with a shutdown in between). I'll give it some time and see how it runs - thanks for everyone's advice.

Answer 1

you didnt clean the battery posts vwell enoulf you arnt getting a good conection somewhere either at the battery or alternator check the voltage at the alternator

Answer 2

Lots of good suggestions given to you already, definetly get the alternator part straight before you do anything else. The alt most likely caused the battery to drop out or atleast helped it along. As far as the stalling goes it could be a variety of reasons, some newer cars have to relearn their idle after a battery is replaced. If you have a bad carbon build-up in your throttle body it can cause the new relearned idle to be set to low (the cabon clogs the throttle plate not allowing it to properly rest in normal idle position, this is especially true if you have a fly-by-wire set-up or electronic controlled throttle). My question to you is after you installed the new alternator and started the vehicle did you notice if the red battery symbol was displayed on your IPC or lower battery voltage meassage appeard on the driver information center part of the IPC, these 2 things showing up are a real good indcation you either have a bad alternator, your cables aren't attached correctly or you have a corrosion build-up on one or both of your cables, all things that can cause the battery to not charge properly and can cause a stall condition if severe enough. If yopu have corroded battery cables and it's not to severe (if the corrosion has penetrated more than about from your pinky finger nail to the first bend, it's to severe and should be replaced) you can use a mixture of hot water and baking soda and a good wire brush to clean it off. Long winded I know but I hope this helps

Answer 3

before they do another swap have them e-prom thecar for codes then its a differant story the electrical system can be affected by a sensor fault the electric ignition and sensors set the fireing and the idle according to a set of circumstances buy the haines for the car and engine its 16 bucks it explains the electrical system but the parts store should try to test for free to avoid another dead part exchange

Answer 4

i own a shop and right now with all the alternator problems your having id get that part of it straitened out first,like you said it had no problems until this happened i have seen them do this before,and as far as getting a bad alternator, i got 5 bad ones in one day,so yes this can happen over and over again,what i did was went to different store and finally got a good alternator,id get that part of it fixed first then go from there,good luck with it,i hope this helps.,,PS be sure and double check all the cables real good.

Answer 5

could be ur voltage regulator, but in most new alts they are internal, check ur cables for bad connection