Greetings!
My LS swapped (5.3 from a 2002 Yukon) Firebird has been having electrical issues. I dont know how long its been happening but it became apparent when i replaced my overcharging alternator. When i start it up the volts read at 14v and it drops a tick when i put it in drive. But if i have any accessories on like headlights or AC, the volts drop a bit more in park and while driving it slowly creeps down to 13v and when coming to stops it starts to sound like its about to stall. Ive had it almost shut off while driving with the AC on. Both the battery and the alternator are new. I've had my OBD2 scanner and my battery tester on them and both state they are good. Alternator is charging normally. Anything i need to look at?

 

A) Where / how are you monitoring voltage? Note: Gauge in the dash is not a calibrated instrument.

B) How did you determine the last alternator was overcharging? Be specific in your answer, please.

C) Why are you blaming alternator for drivability issues?

 

A). Through the gauge. I have New Vintage gauges and have compared it to both when my OBD2 scanner and battery tester are reading and all 3 are reading the same
B). Through my battery tester
C). Idk where you got that from but i clearly wasnt blaming my alternator.

 

how long has this swap been done, like how many miles on it since it was done.

14 volts is not over charging

i run 14.8 in my cars.

going to have to do more diagnosing, but car dying isnt a part of the charging system unless youre under 11 volts

 

I did not say 14v is overcharging. I said the overcharging alternator has already been replaced and the new alternator is sitting at 14v idle, drops a tick when driving, and slowly starts dropping when headlights or AC is turned on. I have to repeat myself here and say that the battery and alternator have already been tested and both are operating normally. Its had the swap for 4 years now.