Low idle when A/C engaged. How do I fix?
07-26-2018, 09:12 PM
#1
Three Wheelin'
Thread Starter
Low idle when A/C engaged. How do I fix?
Hello guys, wondering if anyone can shed some light.
My car's ECU doesn't seem to increase rpm's when a/c is on, so usually wallows around 400 rpms when at stop light. It's never stalled, but how do I test and correct this? If I turn off a/c then it goes to where it suppose to be. weird.
thanx in advance
Jaime
My car's ECU doesn't seem to increase rpm's when a/c is on, so usually wallows around 400 rpms when at stop light. It's never stalled, but how do I test and correct this? If I turn off a/c then it goes to where it suppose to be. weird.
thanx in advance
Jaime
07-27-2018, 01:14 PM
#2
Rennlist Member
Have you had the battery disconnected? might be ecu just needs to relearn load from ecu. ISV (idle stabilization valve) been adjusted? Idle otherwise normal? If your ISV's been adjusted the epoxy in the screws on the end of it would be missing. Or maybe sticky and needs a clean?
07-27-2018, 02:34 PM
#3
Three Wheelin'
Thread Starter
Hey Basal, been a long time! Thanks for chiming in. I'll disconnect battery over night, then reconnect and let idle for 10min. However, in previous years I did exactly this "relearn" when I changed out the engine wiring to new wiring (remember I had gasoline hydralock from an energized fuel injector after I washed the engine compartment-Porsche's wiring loom was at fault, and there is/was a tsb for this repair in the 993). Anyway, I'll try it again, easy enough.
If it doesn't change, can you describe how to go about adjusting idle stabilization valve? thanx in advance
Jaime
If it doesn't change, can you describe how to go about adjusting idle stabilization valve? thanx in advance
Jaime
Last edited by ttAmerica RoadsterAWD; 07-27-2018 at 02:35 PM. Reason: more info
07-30-2018, 12:19 AM
#4
Rennlist Member
Hi Jamie
If it was idling ok before with the ac on, I'd probably just try to clean the isv to see if that makes it 'respond' better. Just take it off and shoot a bunch of wd-40 or something similar into the opening, and rock it back and forth.
If you need to adjust the isv, from memory, if you want to change the baseline idle, you need to use a small screwdriver to remove the epoxy in the ?3screw holes on the end of the isv that holds the valve in relation to the metal body. Mark where it is in relation to the body, (so that you know where you started) loosen the ?3 screws, then turn the inner part (that has the valve) a few degrees one way or the other in relation to the metal body (can't remember if it's clockwise to increase rpm and vice versa). The ecu seems to 'learn' again though and tends to change the rpm back closer to where you started.
If it was idling ok before with the ac on, I'd probably just try to clean the isv to see if that makes it 'respond' better. Just take it off and shoot a bunch of wd-40 or something similar into the opening, and rock it back and forth.
If you need to adjust the isv, from memory, if you want to change the baseline idle, you need to use a small screwdriver to remove the epoxy in the ?3screw holes on the end of the isv that holds the valve in relation to the metal body. Mark where it is in relation to the body, (so that you know where you started) loosen the ?3 screws, then turn the inner part (that has the valve) a few degrees one way or the other in relation to the metal body (can't remember if it's clockwise to increase rpm and vice versa). The ecu seems to 'learn' again though and tends to change the rpm back closer to where you started.
