Weird Idle '91 GT-S - Toyota Nation Forum : Toyota Car and Truck Forums

87TSupra · 08-03-2005, 09:57 AM

I recently replaced the head gasket in my 91 GT-S and now it has a weird surging/high idle problem. I have checked the vacuum lines and tried to check the sensors. The car appears to be in time as it starts up easily and has good power when driving. Has anyone ever had this problem and any ideas on how to fix this?

Pineapple · 08-03-2005, 12:08 PM

Does it bounce from 1500 to 500 rpm?
Could be the ICV - below throttle body. Either its broken or dirty. Use throttle body cleaner to clean it first.

87TSupra · 08-03-2005, 12:25 PM

No, more from like 1800 to about 1100 rpm. I've tried to clean the ICV valve, I took it all apart and cleaned it with brake cleaner. Didn't make any difference.

Pineapple · 08-03-2005, 01:35 PM

Adjust the idle screw. Check and make sure throttle is close when idle, adjust if needed. Check for vaccum leak, broken, missing hose. Spray throttle body cleaner around intake manifold and power steering pump while engine is running. Engine will stall when you spary near or on a leaking hose.

87TSupra · 08-03-2005, 10:46 PM

The idle screw is adjusted all the way down. I will try the the throttle body cleaner and spray around the vacuum hoses. I replaced all of the emissions vacuum hoses, but the idle is still bad.