Hey all, new to the forum, unfortunately to get some advice on repairs. As a little background, I’ve got an 04 F150 with the 5.4l in it. I bought the truck last year for a great price with 145,000 miles on it. Seller gave me all receipts and maintenance records and the truck was evidently very well cared for. 5000 miles in, transmission went out with absolutely no warning (no grinding, warning lights, slipping, etc.). Not a huge surprise as the seller put a lift and leveling kit with 35s on without regearing. 2000 miles later, it started the 45-55 MPH misfire that seems pretty common, so I changed the plugs and COPs. All good. 500 miles after that, it started misfiring real bad (chugging and violently shaking) so I took it in. I should mention at this point that throughout all of this I never got a CEL. Mechanic decided it was a faulty PCM, as it never threw a light, didn’t store any codes, and the PCM signals were all over the place, basically haywire. New PCM. 300 miles later, got a CEL for an open circuit on the camshaft position sensor. Replaced that sensor, and the same code came on 200 miles later. New VVT solenoid. 500 miles later, I go into limp mode, code said that the transmission position sensor was bad. Mechanic found that the PCM was haywire again. He inspected the wire harness and found no damage so the PCM was replaced on a manufacturer warranty. Now almost 12,000 later, I am getting violent misfires again, but every time I clear the codes during diagnosis, I get some combination of the following codes: p0316 p030x. So I take it back into the mechanic and he tears into it, finds the PCM going haywire again and it looked like the cyl 5 injector dumped fuel and scorched the cylinder, which in turn damaged the head gasket between cyls 5 and 6. So my engine is toast, and the likely culprit is a faulty PCM... again. I can afford a new engine to put in, but I feel like there is a case to be made that the manufacturer of the PCM has been selling me a faulty product, which ultimately led to the demise of my engine, so they should be liable. Does that sound crazy?

As a side note, the engine has had the cam phaser tick/knock since I bought the truck, and I’ve always changed the oil with 5W-20 every 2500-3000 miles. Every time the PCM was replaced, all spark plugs and COPs were replaced as well.

 

Maybe... just maybe all you needed to do is the timing job on your truck, given it has 140,000 miles on it (because cam phaser knock). The ECU (PCM) is supposed to disable the injector on a misfiring cylinder if it gets too bad. Also, a bunch of fuel being dropped into the cylinder cools it off, not as strongly as methanol does, but rich = cooler running engine. Sound like you have a mechanic that likes throwing parts at it, instead of actually figuring out that after 140,000 miles you need the timing job done (new cam phasers, VCT solenoids, chains, chain guides, chain guide tensioners, and upgraded Melling M340HV oil pump, as well as lash adjusters and roller followers, which is around $1000-1400 in parts). The ECU on these trucks RARELY go bad.

Once that timing job is done, you run 5W30 oil.

 

Thanks for the suggestion, at this point, it's a little too late for a timing job I'm afraid. I do trust my mechanic, and he always had me come in to look at his diagnosis before proceding with the fix, and he was adamant that I didn't have a timing issue, though I suggested it a few times. My cam phasers were well within range every time I had it in, and oil pressure was good. I ALWAYS ran 5w-30 since I got the truck due to the excessive phaser noise and it definitely helped with that. I will be on the phone today with the PCM manufacturer to discuss the issue. Head gasket definitely blew, evident per compression and leak down test. During some diagnosis, the PCM definitely did not shut the cylinder 5 injector off when it started missing on that cylinder, and I actually threw P0175 after P0305. Then it was just an erratic burst of random codes pointing to open circuits all over the place and misfires. Put good COPs and plugs into cylinders 5 and 6, let the PCM "reset" and everything ran fine until the random codes started flying again about 30 seconds later. Good news is I've got a point A to point B vehicle, so I can take my time and do an engine swap with my spare time after work and on weekends if the manufacturer wont pay for the replacement. Pretty much no point doing all the work to replace only a head gasket on a truck with this many miles, pulling the heads actually sounds a little harder than getting the whole engine out.