2014 w/random misfires (Roush supercharged)

[FordTechOne]

The radio suppressor capacitors turned out not to be what's causing the issue, so we're replacing the PCM next.

Does anyone know of a reputable place to get a new PCM or have mine inspected and refurbished? It would be especially helpful if you have a recommendation for a person/shop that's located on the west coast. Thanks.

Before replacing the PCM be sure that the technician verified all power and ground circuits to the PCM by performing a voltage drop test. This can be done by back probing the PCM connector pins and comparing the voltage reading to battery voltage.

Another test that can be done before condemning the PCM is to place it in a freezer overnight and then re-install it. If the fault doesn’t occur or the symptoms change upon reinstalling it, you can have confidence that the module is root cause.

 

[Canuck714]

Chasing electrical issues is a nightmare..I feel for you.
My gut instinct is that the PCM is not the issue, but can 100% recommend the JDM tune. The Roush tune is garbage!!
It seems that most of the time that you experience the failure, is when under load or high heat offroad type use. I would think that somewhere in the wire harness you have wires rubbing/shaking and creating resistance or grounding out.

 

[W0n70n]

Out of curiosity what do your ground straps and chassis ground points look like? have they been cleaned/replaced recently? I had an issue like this on my truck and it was a failing ground strap from the block to the bulkhead.

 

[Brad12]

Out of curiosity what do your ground straps and chassis ground points look like? have they been cleaned/replaced recently? I had an issue like this on my truck and it was a failing ground strap from the block to the bulkhead.

I personally haven't been able to inspect the ground straps since the truck has been at the dealership, but they said they checked them and they looked good.

I went ahead and gave the green light for them to replace the harness and I got a call yesterday saying they found a "pencil eraser" sized area that had chaffed through, so I think that's likely the cause. I ordered some Flexo F6 wrap that they are putting over the entire harness to try and prevent this from happening again for a loonnnggg time.

The dealership also talked to some Ford engineers who said there is a "1 in a million" chance it's the PCM since the PCM is so unlikely to cause all four cylinders to throw an open circuit code at the same time. That's why I green lighted the harness and it appears we found the issue.

If replacing the harness turns out to fix it, I should finally get my truck back after two months of it being at the dealership. I'll update this thread with some closure if that's the case.

 

[W0n70n]

Glad they found at least some issue and it's not just gremlins that no one can actually point at. Good luck with the fix and I hope it doesn't end up being for nothing. I spent over a year chasing electrical issues with an 05 f150 that ended up being broken solder joints on the gauge cluster causing issues throughout the cab.

 

[Brad12]

Well, I got the truck back and while I haven't driven it a ton, it seems we found the issue. The harness had chafed through right at the intersection where it splits to go to the coils on each side of the motor, so this was likely the issue. You can pretty clearly see it in the pic.

 

[CoronaRaptor]

Well, that's good. What did it cost for the new harness? Hope you can enjoy that truck now.

 

[Brad12]

Well, that's good. What did it cost for the new harness? Hope you can enjoy that truck now.

I got the harness for about $150 (I don't remember the exact price), but it was the labor that made it very expensive to replace.

 

[Brad12]

Well, I'm still having misfires after the harness was replaced. It was driving fine in the city, but about an hour into driving on the freeway and it threw a P0430 catalytic converter efficiency code. I was heading home for the holidays so I wasn't able to deal with it until I got home a few days later, where it also ended up throwing a P0308 (cylinder 8 misfire) code.

I wanted to do some preventative maintenance anyway, so I replaced all the ignition coils and spark plugs (except the 8 exhaust ones) with brand new NGK ones and I gapped the spark plugs to 0.030 as recommended by JDM due to the supercharger.

After that, it ran great on city streets, but under heavy acceleration on the freeway it threw codes P0308 and P0306, the engine sputtered, vibrated fairly violently, lost power, and the CEL was blinking. As soon as I exited the freeway and got back on city streets, it ran fine and the blinking CEL went away.

I found out my battery was bad, so I replaced it with a good battery and tried again. The exact same thing happened, except it only threw a P0308 code and NOT a P0306 code and there was the sound of something clanking. But again, it ran just fine on city streets afterward.

I hit the catalytic converter with a mallet and didn't hear anything rattling around in there, but other than replacing the final 8 spark plugs, does anyone have any suggestions on what it could be?

I also plan to take off the valve cover to see if the valve springs are in good shape.

 

[mprice1234]

Wow, I can't imagine the pain you must be going thru! I hope you can find the issue before you go bankrupt. It's pretty sad when a dealership just throws parts at an issue without doing a through troubleshooting and verifying before hitting you up for more parts and labor. Good luck and keep us posted.