Rpm's Changing

[PrImEtImE]

when my subs are on and i'm at a stop i notice my rpm needle goes up and down a little bit. Is that something a battery would fix? (because i'm gonna get one because of my lights dimming also).

[Fast Eddie]

sounds more like an alt. problem

[bigd6983]

how much power are you running?? (in rms wattage)......at night only?? is your a/c on when this is happening? if your not putting out too many amps with your stereo id say your alternator may be going bad, if you gotta big stereo then its more than likely still your alternator it just cant handle the power.......go get your battery and alternator checked..........

[IndyAlero]

for the light dimming it may seem u should get a capacitor....

[PimpinGad]

The capacitor would probably only work if he wasn't going to run a system, if he is I hear the BATCAP's are the best bet. Capacitor might help a little but doubtful, if your rpms jump up and down that drastically then it's gotta be something run by your belt, maybe the pulley on the alternator is going bad, or just the alternator, but go get dem mugs tested at Pep boy or something. But are you sure you're just not screwing around and turning your wheel while you're stopped cause I can damn near get mine to drop to 500 rpms when I do that at a light. Keep it pimpin.

[mike2002]

cleaning the idle air control motor helped for me

[PrImEtImE]

its really only at night and the rpms only go a very little bit and only when my radio is on loud.

[mikegett]

What year is your car? I have yet to have a delco alt go beyond four years. This includes a 88 grand am, 91 grand prix, 98 accord coupe, and my 97 grand am. My sister and parents have had the same thing. Three to fours years seem to be max on these. My ford was eight years old and over 200 thousand miles with the original alt. When they start to go you will see some funky things happening. My accord had a computerized transmission so it would start to slip. My radio would seem to go loud and low as I sat. The lights dimming seemed to be the last thing.

[PrImEtImE]

Ya i don't think it is an alt. problem cuz' it only happens when my radio is blasting. Soon i'm going to get a really powerful cap. or a nice battery to solve both problems (light dimming and rpm) so it's probably nothing wrong with the alt. I'll just have to wait and see.