High output alternator problem
 

2001 Camaro V6

My problem is at idle with installing a 200 amp high output alternator. The gauge inside the car when it is idling goes into red, the car starts stumbling and other things. When I hold the gas at 900 rpms and higher, then it is charging fine.

The HO alternator has a smaller pulley than the stock alternator, but I kept the stock belt. I am wondering if the stock belt is the problem? Maybe I need a shorter belt or something?

I also have not upgraded the wiring from the alternator to the battery. Could this be the the problem why I am not getting an enough charge at idle? It is crazy low at idle, I don't think it is supposed to be this way.

Please somebody help...ASAP.