I have a 94 F150 with a 5.0 and a 5 speed. My truck was idling at around 1000 rpms. I replaced the IAC, the TPS and the MAP sensor. Now it idles so low that it's almost stalling the engine. Any suggestions on how to bring the idle back to normal?

 

Is the throttle body clean? If it's all gunked up that could be causing some issues like that.

Have you checked for codes?

 

I cleaned the throttle body when I replaced the IAC and the are no trouble codes. Someone suggested replacing the ERG valve, would that help?

 

Unplug the IAC, adjust the idle set screw to where you want your idle then plug the IAC back in.

 

Just adjust the idle screw.

 

How low is it? Mine idles right at 650.

 

This is the service manual procedure.

 

I've checked the service manual and it says there is no idle screw for a 94. I was told to change the egr valve and it should smooth everything out so thats what I was thinking of doing next.

 

Re-ranging IAC Idle

Pre-warm the engine to normal op. temp.

Disconnect the battery for 5 mins. minimum. Reconnect.

Restart. Have someone disconnect the IAC. It should try to dump the Idle/stall.

As this happens, catch the dropping idle w/ the accelerator pedal. Maintain the RPM (Approx. 675 RPM for Manual trans./650 for A.T.) for 2 minutes or longer w/ the accelerator. It will fight this at first, but will settle in.

Shut off the engine for 2 minutes. Reconnect the IAC. Restart engine.

I think the "Idle screw" is referred to as the "Throttle stop set screw", set at the factory & adjustment is not recommended. Is your base timing at least set at stock 10BTDC?

Anytime a sensor is replaced, the Kept Adaptive Memory (KAM) should be cleared. (For OBD1 ECU's, disconnect battery for 5 min. minimum)

 

GOOD POST!

Glad you're back from vacation.