Random Miss that makes no sense.

[bassahaulic]

I have a 1998 GT, Teksid Cobra swapped.

Car has been running fine as it sits for about 2 years, with basic tune ups done every so often.



Other day car started having a bad miss, and idle issue where it would randomly die at idle. If I killed/restarted the motor it would fix it self for a random amount of time.

I changed the the plugs/wires and the miss/idle issue both went away.


Well, fast forward two days, I'm driving home and a small miss comes back and idle issue returns. Get in the car to come to work this morning. Start driving, the small miss is still there. Get on interstate and it goes back to the horrible miss. Still, the kill/restart fixed it for a short time.



I'm at a loss as to where to start. Ideas?

 

[96blak54]

An idea is the coil packs having a crack...? Or wires crapping out.....?

Heat is the culprit here. The items function correctly untill heat distorts the ability to perform. Hopefully you have motorcraft packs and wires.

 

[bassahaulic]

An idea is the coil packs having a crack...? Or wires crapping out.....?

Heat is the culprit here. The items function correctly untill heat distorts the ability to perform. Hopefully you have motorcraft packs and wires.

Actually ended up being a bad O2 sensor lol. Driver side was bad.

I have MSD Coils packs and Ford Racing wires.

 

[96blak54]

Interesting! Thanks for replying

 

[JPhilBradley]

Actually ended up being a bad O2 sensor lol. Driver side was bad.

I have MSD Coils packs and Ford Racing wires.

I was going to suggest looking at an Oxygen Sensor for this problem. When you turn the engine off and then back on, even when warm, it'll take a short while for the PCM to go from open loop to closed loop. In closed loop fuel control the PCM is looking at the oxygen sensors for spark and fuel timing.