I have an 88' mustang that was recently purchased. It is a 347 with H/C/I and the usual goodies. I thought the car needed a 3g swap but after investigating, I realized it already has the 3g in it. The original owner mentioned it needed a tune, could this help the surging lights situation?
Does the car have underdrive pulleys on it? If so, either swap the stock pullies back on, or at least put an overdrive alt pulley on the car.
Even with a 3G alt, the alternator needs to spin at a minimum RPM to produce full charge. Based on the limited info you've provided, i'm assuming your surge happens at idle and goes away with a small bit of throttle? If so, need to spin your alt a little faster
I will agree, either the car has underdrive pulleys or you could have a 3G that is not putting out the correct voltage. I am not much of a fan for UD pulleys myself
I agree as well. My car car has UD's on it and it was doing the same thing before and after i upgraded to the 3G. I put my stock Alt. pulley back on and it really helped my problem.
Hows the battery? I would at least get the battery load tested to make sure its good. Also get the alternator tested, It definitely could be cause by UD pulleys but check the basic things first. Also check the wiring and make sure he upgraded to a larger wire size and didnt use the factory wiring.