No Fire

[Lynn Canez]

I have 97' 4.0 sohc motor in an 99 sport. The problem I am having is finding out why I can't get the #1 & #5 cylinders to fire. I have tested the coil pack, check for voltage from the pcm(even had it flashed). The plugs and wires are brand new. I also tried another coil pack. Still nothing.

 

[slipknotas]

So these plugs have no spark? Have you checked for that yet? Just looked at the wiring diagram and it looks like pcm direct to coil. So check wiring from pcm, maybe try a new coil or a known good one(not sure if the one you swapped was), and if that don't work looks like it could be a bad pcm. Trust me I feel your pain, mine is abs though.

 

[2000StreetRod]

waste spark ignition

Your Explorer has a waste spark ignition system. There are only three coil sections in the coil pack and two plugs fire simultaneously for each coil section. Pairs are 1 & 5, 2 & 6, 3 & 4. A bad plug or wire for cylinder #1 can impact cylinder #5 and vice versa. I suggest that you measure the resistance of the plug wires - one may be broken internally having very high resistance. Also check the gaps on the plugs. If not excessive then measure their resistance. Unfortunately, defective new plugs occasionally occur.

There is a trigger wire from the PCM to each coil section. My wiring diagram does not indicate which one is associated with coil section for 1&5. Neither does my Haynes Repair Manual. Check the electrical connector pins for proper alignment and the wires going to the connector. Make sure the connector is pushed on completely.

 

[Lynn Canez]

Thanks for the reply, I just had the pcm flashed so I'm assuming that it is good and as for the coil pack i had swaped it with 2 other ones that I know they are still good. Even one of them I have in another explorer that I drive myself.

 

[Lynn Canez]

2000stretrod, thanks for the reply, I just checked the plugs and wires. They both are fine. Going to try and track down those wires. I will let you know what I find out. Thanks again.