4.0 Electrical Problem

[ET]

I have a 94 Ranger with a 4.0 I was out this weekend driving around the dez.. and it started runnin pretty bad. It sounded like it was only running on a couple cyclinders. i pulled the plug wires at the coil and only the back two were sparking. I went and bought the new coil pack or whatever it's called and it fired right up only to run about 5 minutes and back to only running on two plugs? Any sugestions???

 

[Bob Ayers]

It could be the ICM (Ignition Control Module) which has the open collector coil drivers in it. But, try reseating the connector on it first.

 

[ET]

How do you reset it?

 

[Bob Ayers]

How do you reset it?

Reseat, not reset......Unplug the connector, and plug it back in.

 

[ET]

Oh.. I did unplug it and made sure it was clean plugged it back in, I also replaced the plug wires. I started thinking it could be the computer because it started back firing when i was trying to start it. This is currently my daily driver so i don't know what to do??

 

[KELLY88]

Any check engine lights?

 

[ET]

Yeah but i swaped the cab on this truck so some of the instrument panel is jacked. The cab i used was off a 94 3.0 that had 346,000 miles on it so interior is pretty nar.. The truck actually has 116,000... I know that typically the computers don't go bad but when i originally did the swap i forgot to take out the 3.0 computer and it did this very same thing. i quickly put the 4.0 computer back in it and it's ran perfect ever since. I just can't figure it out. Only the coils closest to the firewall are sparking.

 

[ET]

Fixed it !!! two wires leading out of the harness close the the computer somehow shorted against each other. it took some hunting to find them but the truck runs good now. Oh yeah but i had to buy another Coil Pack

 

[KELLY88]

Well done. Small electrical gremlins like that can be a real PITA to hunt down.