I keep getting a misfire even after I changed everything could it be the pcm?

Question

I have a misfire on cylinder 6 i changed ignition coils spark plugs fuel injectors fuel filter could it be the pcm? I had got a code TCM:U0100 but I just cleared the code my car still runs and everything it just have a rough idle I have a Dodge Charger 2014 3.6 v6 car

jack62 · Accepted Answer

The CAN Bus communication code (TCM U0100) indicates the TCM (Transmission Control Module) is not receiving or transmitting messages on the CAN Bus (at the time the code was triggered). It must have been a short lived event or your transmission would have went into a safe/limp mode.

Whatever triggered the code (open/short in the CAN Bus wiring/connectors, weird fault in the TCM), you cleared the code, it didn't come back, so the PCM and TCM are on "speaking terms" again.

That wasn't/isn't the cause of your #6 misfire.

The fact that the issue is more prevalent at idle points to a vacuum leak.

So maybe confirm when it's throwing the code by observing your Freeze Frame Data, clearing the code, observing the FF Data again (when the code is triggered again), (and do this a few times) to see if the code is always being triggered at idle when a vacuum leak will have more of an affect on the combustion mixture.

Pay attention to what the fuel trims are doing on that side of the engine. What the RPMs and ECT are.

Are the fuel trims higher on the positive side at idle and diminish as RPMs increase on that cylinder bank?

If it's always happening at idle then you could spray carb cleaner around that cylinder's intake manifold area but chances are you'd miss a leak on the lower side so ideally you'd have a Smoke Test performed (with good equipment) to either determine if a vacuum leak is the cause of the misfire, (or rule it out).

The thing is, this is a cylinder specific issue and you've "bombed" this cylinder with every replacement part you can. (Plugs, Coil, Injector).

So what's left?

We can't say the fuel injector isn't getting battery voltage or a PCM ground signal, because the car runs good at higher RPMs.

We can't say that the "COP" coil isn't getting battery voltage or a switching signal from the PCM, because the car runs good at higher RPMs.

That leaves Compression. (You can do a Compression and Leak Down Test)

Or a Vacuum Leak on an intake manifold gasket. (You can have a Smoke Test done)

Whatchamacallit · Answer

See below under ‘Mechanical’ section:  did you perform a compression test? (and compare with the other cylinders?) https://repairpal.com/obd-ii-code-p0306