WHAT THE HELL IS THE CAUSE OF VOLTS DROPPING UNDER SLIGHT LOAD AND THEN SHOOTING BACK UP 10 12.5 TO 13v?! I''ve cleaned all the grounds and positive contacts w/ no luck! ARGHHHHHHHHHHH!

Crank the car no problem and holds a steady 12.5 to 13v. The minute you put your foot the lights dim and the volts drop down to 7 or so and once past 2500 rpm's the shoot back up and hold steady all the way to redline. This is killing me as I don't have a clue. New Optima...waiting on a 200a alt to arrive w/ new battery cable kit with 1/0 guage. All fuses are fine and no codes. I tried a used alternator from a friend and had the same problem but it works on his. WTF??!! The car would be a rocket but the minute I stab the throttle it'll stumble because the volts drop then after 2500 I'm off.

Somebody has to have a answer. I'm getting ready to try my other set of coils for my delteq to see if it's a bad coil or something...I'm running out of ideas.
Thanks.

 

Since you have a new battery and you used an alternator from a friend we have to assume you have a bad connection somewhere since your voltage was low. 13V is low compared to normal operation. Either one of the positive cables is bad or a ground wire is bad.

If you assumed the friends alternator was workin correctly, you should go through the wiring carefully. Pull off and clean the positive cluster and the negative cluster on the passenger fender. Pull the ground strap and clean it and the ground near the starter just for good measure.

Just takes careful investigation to find it. I hope the 200A alternator didn't cost too much since it sounds like the alternator is not your problem.

Dave

 

sounds like an alternator to me, even though you said it was not

 

I cleaned all the contacts off as well as where it was grounded to. Scrub the paint off clean just to make sure. Only area I didn't touch was the passenger side and the starter contacts. Could it be heat perhaps as my starter is right there next to the header even though I've had these headers for yrs as well as the same starter w/ out incident.

300 bucks for the alternator. Have a new battery kit enroute so if it is wiring hopefully this cures it.

Thanks guys I appreciate the responses.

 

Weird but I think I found the problem. The one wire pigtail had a 90* bend and all I did was straighten that out. Cranked the car and 14.5v and no dip under load! That wire has been bent for ages and never gave me a problem before but for some reason it did. The only other thing I can think of is it's something in the fuse panel inside the car. I had it off for awhile and put it back on and now the ABS and E-brake light stay on.

Weird I know but I'll see if it's the panel for sure tomorrow....as I'm happy I have full voltage now. 200a alt on the way for nothing. Oh well it'll serve well w/ the other crap I'm throwing on there shortly anyways.

 

I seem to recall someone telling you it wasn't the alternator since the friends you put in didn't change anything and also telling you to go through the wires.

But I'm just working from memory and I may be mistaken.

 

LMAO