dwb
Proven Member
- 813
- 560
- Sep 9, 2021
-
Broomfield,
Colorado
When I start turning on power hungry accessories - blower, headlights, rear defroster, etc. - my idle becomes a little erratic. It idles a little lower and the engine runs a little rough. Sometimes when coming to a stop the engine stalls or barely catches in time when all the accessories are on. The more electrical load, the worse the symptoms.
I have a 90amp alternator, a lifetime warranty unit from Advance Auto. Charges good at 13+ volts. My idle is 750rpm most the time, ISC is good, blocked FIAV, idle switch working, TPS set correctly, and no major boost leaks. I set curb idle per the vfaq by grounding the firewall plug and the pin on the diagnostic plug.
Obviously extra electrical load causes more load on the alternator which takes more mechanical power. But why doesn't the ISC account for the extra load and most importantly, why would it not always catch idle when coming to a stop? It never has a problem catching idle if the headlights are off.
Thoughts, ideas?
It's a 91 TSi AWD mostly stock.
I have a 90amp alternator, a lifetime warranty unit from Advance Auto. Charges good at 13+ volts. My idle is 750rpm most the time, ISC is good, blocked FIAV, idle switch working, TPS set correctly, and no major boost leaks. I set curb idle per the vfaq by grounding the firewall plug and the pin on the diagnostic plug.
Obviously extra electrical load causes more load on the alternator which takes more mechanical power. But why doesn't the ISC account for the extra load and most importantly, why would it not always catch idle when coming to a stop? It never has a problem catching idle if the headlights are off.
Thoughts, ideas?
It's a 91 TSi AWD mostly stock.