Rough Idle - P0354 code - SES light is on

[Dr_Z]

Hi folks - this one has me stumped...

2002 Ford Explorer 4.6L 4x4


My SES light finally came on at 128k miles. It was expected because of the mileage, so I figured it was time for the 100k maintenance. There were several codes showing up when I scanned initially, and I took some steps to eliminate them one by one. I'm trying to get things cleared up before next month's emissions inspection.

Here's what I did initially...

- Cleaned MAF sensor
- Wouldn't idle - replaced IAC - now it idles fine
- Replaced all the plugs - surprisingly, the old ones didn't look too bad
- Examined and cleaned carbon from EGR and surrounding area

Now my final problem and code is P0354 (Ignition Coil 'D' Primary/Secondary Circuit). Here's what I've tried to do to clear this one up.

- Replaced all plugs (see above)
- Visual exam of area shows nothing unusual with wires and coil
- Replaced spark plug boot and the corresponding internal spring/wire
Still same code. Cleared code.

- Swapped the coil on 4 (D) with the one on 8 thinking that if the coil was bad, the code would change after the swap.
Cleared code. Started engine and still have the P0354 code from the D cylinder. So I figured it wasn't the coil.

- Pulled coil connection and checked both sides with a test light.
- One side showed positive 12V.
- Started the engine and checked the other side against ground. The test light showed steady flashing.
Cleared code. Started engine. After driving a block, the SES light comes back on and it's the same old P0354 code. This is also the only code that shows up.

So what the heck? Connection seems good. Coil swap didn't do anything. I can't see any obvious worn / shorting spots on the wiring harness. It's hard to tell if the engine is actually missing. Idle is a bit rough, but engine smooths out when driving.

Any other checks you can suggest? I could buy a new coil, but I thought that by swapping coils with another cylinder I've eliminated that problem.

I've got a code reader, a digital multi-meter, a powered test light, and half a brain, but I'm running out of ideas...

Thanks in advance...

 

[lincolnshibuya]

could be your PCM but check the wires between your COP and PCM.

https://www.youtube.com/watch?t=831&v=ho3Kyps2i34

 

[Dr_Z]

could be your PCM but check the wires between your COP and PCM.

https://www.youtube.com/watch?t=831&v=ho3Kyps2i34

Thanks - I was thinking the wires would be OK, but I'll give them these checks and see what I come up with. I just hate to go to the dealer before I've tried everything...

 

[Dr_Z]

Forgot to post a solution.
The fix turned out to be installation of a fuel injection connector with pigtails on the D injector. That was it. Engine smooth as silk now (at least for a while).