This is for a friend. Engine shuts off while coasting down hills or stopped idling. What could cause this? New plugs, wires, opti. Is the car idling to low? I think it is still idling at stock rpm.

His car idles at 700 rpm, my car idles at 1,100 rpm.

 

My car idles right around 500 and it's fine, doesn't bog down or nothing. maybe he has some tranny problems bogging it down, idk. That's a tough one.

 

My car used to do this after heavy nitrous runs. It would die at stops and in neutral. My engine later died from low oil pressure. Make sure he has good pressure; it might be a sign.

 

The IAC valve opens up to prevent stalling on closed throttle coast down. As long as the car is rolling (VSS not = to "0") the RPM should stay above the normal "idle speed". Maybe the IAC passages are plugged up or the IAC valve is dead.

 

Wouldn't you throw a code for a bad IAC? Just asking, because mine died while pulling into a parking stall today. I had my IAC off during the rebuild to clean it. I used carb cleaner and a brush and didn't take apart the spring or plunger.

Thanks:

ZMAN

 

Update: I think it is a fuel system problem. The car cuts off like it is running out of gas. The car died and didn't start for awhile. After adding dry gas to the tank it was able to be started up and driven home.


Is this a sign the fuel filter is clogged possibly?

Anything else I should check?

 

There is no code for the IAC valve. It could be completely missing and not set a code in OBD-I. The PCM reading is simply what the PCM is commanding the valve to move to, there is no feedback as to whether the valve is actually doing what its told. You will eventually get a code for idle speed out of range in OBD-II, but not in OBD-I.

If you feel there is inadequate fuel, check the fuel pressure.