Troubleshooting P0301 misfire

[Zpak]

Ok not my SHO but my brother-in-laws 2012 3.5 Ecoboost F150.

It started with a P0131
Bank 1 sensor 1 low voltage

He rode on that for a couple weeks. He checked and cleaned the plug for the O2 checked a few other things then cleared the code. It came back a couple days later so he bought a new upstream O2. Literally on the way home from buying the sensor the rough idle started. Got home pulled the codes and now in addition to the P0131 he had P0301 cylinder 1 misfire. Figured they were related so changed the O2 and cleared the codes. Still running like trash, CEL still on, P0301 for the misfire. I had him swap the plug and coil to 4. Code stayed with cylinder 1. Original plug as well as new plug moved to 1 looked like this.



So at that point we were both thinking must be the injector. We changed the injector, no difference, same P0301 cylinder 1 misfire.

Thanks for reading guys. I’m at a loss now. Outside of shot rings I can’t think of anything else it could be. He’s going to do a compression test after work tomorrow and poke around with a scope. Any help, advice, direction, or information would be greatly appreciated.

 

[SM105K]

Have him pull the negative terminal tonight.

 

[SHOdded]

Looks like possibly valve cover gasket at this moment, tho it could be a defective piston ring as you suspect.

1. Does it feel like the engine is misfiring?
   
2. Have you checked the values on the VCT advance error PIDs?
   
3. Has the intercooler mod been applied, or has the intercooler been upgraded?
   
4. Have you checked compression?

You can get a USB borescope to inspect the cylinder in question, pretty easy since it is a longitudinal configuration.

 

[Zpak]

Appreciate the replies.

Battery was pulled for three days waiting on the injector job. Most definitely a miss, rough idle and bucking. Compression test will be done tonight. I’ll report back on that. No intercooler mods, everything is bone stock. The plug, boot and well were completely dry on top. Have not checked the VCT advance error PIDs. I only have a basic OBDII code scanner.

Edit: sorry, plug was dry.

 

[Zpak]

News!

Compression test was good. So that’s a relief. Ran the engine and pulled the plug completely on the coil pack made zero difference. So it seems it’s not misfire, it’s no fire. It’s not getting spark.

Three wires to the plug, two for power one for signal. 12v power tests good to the plug but what doesn’t is signal to fire. So, still dead in the water but there is a glimmer of hope as it seems there is no physical engine damage.

 

[SM105K]

News!

Compression test was good. So that’s a relief. Ran the engine and pulled the plug completely on the coil pack made zero difference. So it seems it’s not misfire, it’s no fire. It’s not getting spark.

Three wires to the plug, two for power one for signal. 12v power tests good to the plug but what doesn’t is signal to fire. So, still dead in the water but there is a glimmer of hope as it seems there is no physical engine damage.

That is good to know. I was really hoping it wasn't ringland or something goofy.

 

[FiveLeeter918]

Was gonna say the plug looks like you're crazy rich, but after reading and you saying it's not firing at all, there's your answer.

Just to make sure, you are calling cylinder 1 the passenger side front cylinder correct?

 

[SHOdded]

So that is the coil or the coil driver. Generally don't see failures of either on ecoboosts, but this being a 2012, age could be a factor.

If it is indeed the coil driver, you may be able to get the PCM repaired by circuitboardmedics.com. Check the harness carefully in case a wire has depinned.

 

[Zpak]

Was gonna say the plug looks like you're crazy rich, but after reading and you saying it's not firing at all, there's your answer.

Just to make sure, you are calling cylinder 1 the passenger side front cylinder correct?

Yes, thanks for looking out Lee.
And I know crazy rich! that’s why we changed the injector. After moving known good coil to #1 it was the only thing that made sense. Guess we were both wrong.

 

[Zpak]

Any thoughts on possible bad crank sensor?

 

[SHOdded]

I don't see a crank or cam sensor causing a misfire. No fire, maybe, but usually a trouble code will set or the PCM will initiate lower power routines to compensate. Of course, codes are set after a threshhold is met, and if the sensor is weak but not weak enough, the PCM would keep doing what it is supposed to do, and you'd be none the wiser.

If you really want to check it out, put it on a scope and watch the waveforms under varying load conditions. It helps to have a reference (known good), but if you see irregularities where there should be none, then you have found a problem.

You could also have a problem that requires teardown to discover. Sometimes the crank tone ring will crack, or the harmonic balancer/crank pulley will be worn. The PCM may not react, but you would feel the effects down the road in vibration/harshness, if the knock sensor does not pick it up first. No knock events, right?

Maybe look at Mode 6 data? Not sure how useful that is on Ecoboost engines, but we use on nat asp engines all the time.