Rodrigo

Working on my 2013 F150 Lariat SuperCrew, 3.5 EcoBoost. Currently at 145k miles, but the problems started 5k - 8k miles ago. I've been chasing misfire problems all summer and I'm ready to lose my mind.

Back in April I got a flashing CEL while nearing the end of a 300 mile trip while towing a load. Limp into OReilly and read code P0304 (using their scanner). Pulled the coil and found it melted. Replaced the coil in the parking lot; it ran smooth and was back on the road in 15 minutes.

Experienced the same symptoms about a month later in the middle of a trip. Limp into another OReilly, and read the same P0304. The #4 coil looked ok, so I put in a set of new plugs in their parking lot. Truck started and ran smoothly; finished the trip without event.

The remainder of the summer I would go weeks without a problem. Then out of the blue I'd get a flashing CEL. I found that pulling over and shutting down for a minute would smooth things out. Sometimes the CEL would be lit afterward, sometimes not. But even if it stayed lit after an episode it would typically turn itself off the next day. A couple of weeks ago I put in six (6) brand new Motorcraft coils. Everything seemed to be running great until a few days ago. At the end of a long trip the truck starts misfiring with a flashing CEL. Forscan reads P0304,P0316, and P2309 - Ignition Coil D Primary Control Circuit Low. I pull the (2 week old) coil off #4, and it looks like this:


Mode 6 data in Forscan does show a couple/few misfires in other cylinders, but I clearly have something going on in #4 that is cooking my coils.

The only think I think this can mean is I have a wiring/grounding problem somewhere in the wiring between coil & PCM, or in the PCM itself. I did verify continuity in the three wires between the coil plug and the PCM plug. Not sure what else to check or how to go about it.

Can anyone point me to a source or reference that walks through these troubleshooting steps? Do I just have to start peeling apart that wiring harness to look for a pinch or crimp? A bad splice somewhere? Is there a process anywhere to determine if the PCM is at fault?

Thanks for your advice.

Rodrigo

Well right after I post my question I find this:
Guess I'm heading out to open the hood and trace the harness path.

Update: Traced the path of the entire harness on top of the engine, but didn't note any spots where it was obviously damaged or rubbing on something it shouldn't be.

flyswat446

Did you take out the plug on #4 and make sure the sealing surface is not compromised? Also, are all misfires on one side?

13fx4150

Was there any oil or moisture in there?

Rodrigo

The second time I got the flashing CEL back in the spring I replaced all the plugs. I didn't notice anything goofy going on in #4 (or any of the others, for that matter) but I wasn't really studying plug wells super closely, either.

The catastrophic misfires are always in #4. However, Forscan tells me I sometimes have individual cold start misfires in other cylinders on both sides.

The blinking CEL appears to be rooted entirely in #4.

When I most recently fried the nearly-new Motorcraft coil a few weeks ago, I briefly thought I had some oil in #4 plug well. I realized it was not oil at all, but more likely resins leaching out of the melting plastic cover of the coil.

I do have an update to share. I bought a junkyard PCM and had it cloned to mine a couple weeks ago. I've driven maybe 1k miles on it and haven't had the problem resurface. I'm not ready to close the case yet because I would go for weeks and weeks without a problem over the summer. If the problem resurfaces I would have to think it's not in the spark generation side of the equation.

flyswat446

Fingers crossed that you fixed the problem.

13fx4150

Hopefully that fixes it. Please keep us updated so future folks who have this issue can look into that.