Need your help on this one...
Recently I noticed that my car idles at 500 RPM but at night, with the headlights and interior lights on, the car idles at 900 RPM. I had the battery checked out and the battery is fine.
My car is a '99 with 34,200 miles on it so I'm thinking it isn't the alternator that could be the problem... but then again I did get a system installed about 4 months ago which could contribute to the alternator being the problem.
I'm wondering what the problem could be? I was thinking the alternator could be the problem... or maybe the timing needs to be adjusted?
Feedback on this issue would be much appriciated...