How do I increase the engine idle on a V8 EFI 302? (1986 Cougar)
Cause after the engine idles down it stutters and then stalls.
As far as SEFI you really can't increase the idle. I suspect your Idle Air Control motor to be at fault. Don't adjust the screw on the TB, though.
Mine will do that when the temperature is at a certain point. I couldn't tell you offhand what it is, maybe mid-30s, but when a day comes that it is that temp, I can tell you that my car will do it. If it is warmer, or colder, it's fine.
With the engine warmed up(and off), disconnect the IAC. Restart the engine and see if it will idle on its own, if not adj the screw on the throttlebody for a slightly less than normal idle. This usually helps a cold stall. If you still have a problem, clean the IAC(would be a good idea anyway). Problems after these would indicate a out of calibration temp sensor, dirty injectors, maybe even a bad fuel pressure regulator(was the problem on my nephews 4 cyl Stang).
Bring the engine up to normal tempurature.
Disconnect the battery for 5 mins to erase eec.
start the engine and allow it to idle for 2 mins to relearn idle speed.
Check tps voltage - .98-.99v between black and green wires KOEO.
If your problem persists repeat the process but adjust idle screw before the 2 minute idle session