Engine dies while idling

[chaka]

Engine is a 302 in an 86 F-150. It runs great above idle wether or not it is warmed up or not.

When idling while partially warmed up or completely warmed up the engine will begin to die and then surge. repeats a few cycles and dies. Does this in every gear when car is stopped. Once car is moving engine has no problems.

At a stoplight it will hesitate off idle and then run smoothly once the idle is up.

When the engine is dying and surging the voltage will drop to 12.5 and rise to 13.5. Above idle the voltage varys between 14.2-14.5. Voltage does not rise above that.

Also the air pump pulley is removed because the air pump is seized. Besides that everything is stock setup.

How can I fix this?

Recent tuneup before I purchased with motorcraft parts. The P/U then sat for a year.

 

[gt90stang]

A few things to check:

1. could be ISC, check to see if it works by unplugging while idleing. RPM should drop and maybe die if the ISC was working.

2. If no change in 1. above the ISC may need cleaned or replaced.

3. Battery in good condition? Voltage fluctuation could cause what you are seeing.

Good Luck, Don

Engine is a 302 in an 86 F-150. It runs great above idle wether or not it is warmed up or not.

When idling while partially warmed up or completely warmed up the engine will begin to die and then surge. repeats a few cycles and dies. Does this in every gear when car is stopped. Once car is moving engine has no problems.

At a stoplight it will hesitate off idle and then run smoothly once the idle is up.

When the engine is dying and surging the voltage will drop to 12.5 and rise to 13.5. Above idle the voltage varys between 14.2-14.5. Voltage does not rise above that.

Also the air pump pulley is removed because the air pump is seized. Besides that everything is stock setup.

How can I fix this?

Recent tuneup before I purchased with motorcraft parts. The P/U then sat for a year.

 

[chaka]

Battery is new and all connections are snug and corrosion free. Have not tested the voltage drop across them since I have no starting problems or charging problems.

I am not sure if it is the ISC but I unplugged a cylinderical one on the side of the TB with two wires. (I thought it was the Air bypass valve?) And the engine died.

A few things to check:

1. could be ISC, check to see if it works by unplugging while idleing. RPM should drop and maybe die if the ISC was working.

2. If no change in 1. above the ISC may need cleaned or replaced.

3. Battery in good condition? Voltage fluctuation could cause what you are seeing.

Good Luck, Don

 

[gt90stang]

Chaka,

Yes, that is the ISC (idle speed control) and it does bypass air around the throttle plate. I'd adjust the throttle plate so that with the ISC disconnected so it can barely idle. Then reconnect the ISC and reset the KAM by disconnecting the battery for 10 minutes. Re-connect the battery and see it this helps fix the problem.

Good Luck, Don

Battery is new and all connections are snug and corrosion free. Have not tested the voltage drop across them since I have no starting problems or charging problems.

I am not sure if it is the ISC but I unplugged a cylinderical one on the side of the TB with two wires. (I thought it was the Air bypass valve?) And the engine died.