C4 runs rough when charging
Thread Starter
1st Gear
Joined: Jan 2009
Posts: 1
Likes: 0
From: Pinellas park Florida
C4 runs rough when charging
I recently had the trans. in my Vette changed from manual to automatic. The car now has a very erratic idle, it coughs chokes misfires and backfires. But when I unplug the alternator, it runs perfect. I tried tracing the wires back from the alternator but I can only go so far. I would like to know if anybody has any idea of where I go from here. I thank you all for any suggestions. I forgot to mention in the original statement that my Vette is a 1987, sorry about that.
Last edited by willmorn; Jan 27, 2009 at 04:31 AM. Reason: I never had the year of my Vette
Melting Slicks
Joined: May 2007
Posts: 2,171
Likes: 1
From: Warwick RI
I recently had the trans. in my Vette changed from manual to automatic. The car now has a very erratic idle, it coughs chokes misfires and backfires. But when I unplug the alternator, it runs perfect. I tried tracing the wires back from the alternator but I can only go so far. I would like to know if anybody has any idea of where I go from here. I thank you all for any suggestions.
I missed the year of your car but it doesn't matter until you look for the idle procedure anyway.
Basic old school troubleshooting here but commen sense has always worked well for me. You increased the load at idle with the Auto swap. It is not in your wiring for the alternator, it will have a load when it charges. The idle should adjust automatically but it wouldn't hurt to do a complete idle adjust procedure to see if that fixes it. It may just be idleing too low and that is what you feel as rough. This would also cause your alternator output to be low and take longer to bring the battery back up after start.
Race Director
Joined: Jun 1999
Posts: 14,924
Likes: 9
From: Merritt Ils Fl
Iroc57 is most likely on the right track but there may be another possibility. For some years the program in the chip are different for an automatic and a stick. Haven't looked at the 87 to be sure but it might be worthwhile to look.
