Hey all,

Recently my 88 Iroc with the 350 TPI has been having weird idling and voltage dip issues. The voltage on my car while idling will randomly dip down to a little over 9 volts for just a second and come back up around 13. When this happens, the car will feel like it stumbles and the rpm drops, but only for a second. This tends to happen with the AC on. The car still has erratic voltage and idling behavior without the AC on, but I’ve noticed the more strain I put on the electrical system, like having the lights on, AC on max with the fan full blast, blinker on, etc the worse it gets. It’s especially bad if the car is in gear, I.e I put it in reverse and keep my foot on the brake. This happens intermittently, and it did stall on me once at a stop light. Any ideas what could be causing this? No check engine light has come on. Recently replaced: ECM, distributor cap and rotor, MAF burn off relay, IAC, fuel filter, ignition control module. Thanks in advance for any input.

 

It might be a good time to perform a hot load test on the alternator. Many parts stores will briefly test an alternator for output current and regulated voltage, but will not get it to full temperature (it take time). Unfortunately, that is one of the few ways to test the integrity of the rotor winding and insulation, output rectifier performance at temperature (forward voltge drop and PRV of a diode changes with temperature), and the reliability of the solid state regulator.

Inspecting all the alternator and battery connections would also be adviseable.