2014 Ford 3.5, #3 Misfire Intermittant

If it has any history of engine replacement, timing chain work, etc, try performing the “Misfire Profile Correction Relearn” procedure in the scan tool. This is the PCM's learned position of the crank trigger wheel, if the “Actual” position varies from the “Learned” position, it can cause the PCM to fire the coils at a slightly incorrect time. The symptom of this is typically intermittent…

What plugs were installed? And was the gap checked when they were installed?

I would suggest scoping the ignition during the misfire to see whether you have a fuel issue or a spark issue or perhaps a mechanical issue. Once you determine that then you can focus your efforts on that system. Maybe a wire with high resistance to the coil or something like that. You gotta find out where the problem is before you can know what to investigate to fix.

You could rule out valve train issues by using a pressure transducer in the intake and another pressure transducer in the tailpipe while cranking the engine. This capture is from a 2016 Challenger 5.7 that only misfired near WOT. The red channel is the starter amps. The green channel is a pressure transducer in the intake and it shows 1 cylinder with a poor intake vacuum pull. The blue…

Hi Allen, The 3.5 engines have had a history of burning the PCM coil drivers in the past. A scope should find the issue. Was a Motorcraft coil and plugs used? Did swapping coil to another cylinder change anything? If you are using mode 6 for cylinder miss counts, keep in mind that a companion cylinder on the same crank journal can be the possible true fault. Misfire data is recorded by the…

I had a client that I programed a used pcm computer and that was not the problem than we changed the in ignition coils not the problem change spark plugs not the problem there was a air leak in the turbo system problem fixed this sounds like the same problem

What are you fuel trims doing during misfire? Monitor O2s while you perform a VE Test. It may be an injector not supplying enough fuel at WOT.

at the end it was a leak in the turbo chamber, intercooler. So it lost power at 4500 rpm

How many misfires are reported in mode 6 data? Check mode 6 for any other cylinder misfires.

Hi Allen, What are you after here? With due respect, I see that things have been done and you still have a misfire. What I don't see is what you want. Are you looking for an informed guess at which part to replace next? Would you like input on further testing to do or how to do it? I want to help. What kind of help are you looking for? Compression testing is kind of like ohms testing. Bad…