Idle Charge issue

EF5.0 · Dec 19, 2012

Don't know for sure if here or the 5.0 specific forum is the right place for this question but I'l ask away here first since it is electrical.

94 5.0 stock except for CAI

When I am sitting at idle (stoplights, driveway etc..) the car idles really rough, rpms drop down to about 400-500 and the Amps jump back and forth from the O to the A in NORMAL.

It doesn't run as rough when I have my headlights off, but still idles bad, (only really goes up by maybe 50 rpms guesstimate).

Does anyone have an Idea of what it could be? I am going to do a tune up (plugs, wires, cap, rotor) this weekend and hoping that helps, but hoping for some other input or ideas. Can't really find anything definitive through search.

CC'S95GT · Dec 19, 2012

do the tune up first with standard replacement plugs, don't forget the fuel filter too. clean the MAF and IAC as well.
the reason the amp guage bounces is because the idle is to low.
You may need to do a "base idle reset" if it's not any better after the tune up. (there is a sticky for it in the 5.0 section)
keep us posted.

EF5.0 · Dec 20, 2012

Will keep everyone up to date. Plan to do the tune up Saturday.

EF5.0 · Dec 28, 2012

Little update on my issue. Tune-up completed, Idle is better, but the Charging still seems to struggle. But I did find a catalyst for the amps spiking.

They only drop or spike when my foot is on the brake. So I believe that maybe when we put the new tail lights in one of the grounds is either loose or is touching something it shouldn't be. I plan to take them off tomorrow to check.

CC'S95GT · Dec 29, 2012

have someone else step on the brake pedal while you look at the lights to see if any are extra bright or dimmer than the rest.

EF5.0 · Dec 31, 2012

Ok, Checked the tailights, other than a faulty bulb no issues. The rpm's have quit jumping at idle, now it is just the Amps... I believe it may just be the alternator, or maybe a loose engine ground. When it warms up a bit I will work on tightening all of the engine grounds and then if that doesn't work have the alternator tested...