Forscan misfire counts

[scoobaru88]

So I’ve been trying to figure out this annoying misfire I’ve had for a couple weeks. It only showed a check engine light twice, but in forscan mode 6 scan it picks up counts on all cylinders, highest being cyl4 and second highest being cyl3.
Thought it was bad gas so I drained tank and switched back to e85.

I’ve done new plugs, new injectors, checked fuel pressure, sent a log to tuner and they said everything looks good. Tried crank relearn, and kam reset. Checked the imrc on intake manifold(not broken). I was thinking possibly coils, I swapped cylinder4 with cylinder 5 and it made no difference in the counts. Misfire happens about 1500rpms, not bad but can be felt while driving. Car is driveable as is.

Anyone have other ideas? Gonna do compression test tomorrow but unless the whole engine is done I don’t see it being a problem (misfire counts on all cylinders).

2019 Mustang GT, ess g3x 100mm pulley, fic1200 injectors, four 285 fuel pumps, bmr solid motor mounts, 2m headers.

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[ice445]

Did you check the long term fuel trims? Could be a vacuum leak ahead of the manifold. Or a MAF that needs cleaning. Or does the ESS kit delete that and use a speed density setup?

 

[scoobaru88]

Did you check the long term fuel trims? Could be a vacuum leak ahead of the manifold. Or a MAF that needs cleaning. Or does the ESS kit delete that and use a speed density setup?

It uses the MAF, I don’t remember what the LTFT was but tuner said logs looked ok. I can check the LTFT today.

 

[Cory S]

Have you check the plugs lately? Ie: loosened up/plug gap under .028”?

 

[scoobaru88]

Have you check the plugs lately? Ie: loosened up/plug gap under .028”?

Yes. New plugs set to .026. I tried tightening them too .024 and no change. Tuner checked logs and said everything looks perfect. Fuel trims within a few percent and holding stoich.

I went for a 10mile drive yesterday and then checked the misfire counts. Cyl 1-2-3-4 all over 100counts, with cyl3 at 200counts and cyl4 over 300. Cyl 5-6-7-8 were anywhere from 10 to 30counts.

 

[Cory S]

Yes. New plugs set to .026. I tried tightening them too .024 and no change. Tuner checked logs and said everything looks perfect. Fuel trims within a few percent and holding stoich.

I went for a 10mile drive yesterday and then checked the misfire counts. Cyl 1-2-3-4 all over 100counts, with cyl3 at 200counts and cyl4 over 300. Cyl 5-6-7-8 were anywhere from 10 to 30counts.

Man that’s annoying. Having all cylinders acting up means it’s probably something in the tuning then. Maybe….
Crank sensor acting up?

 

[Einstein_nikola]

I once had this happened to a friend with a Gen3 , we disconnected the battery for a whole day to let the ECU drain out and of course cleared the codes before we removed the battery and it never came back, he had a whipple setup

 

[scoobaru88]

Man that’s annoying. Having all cylinders acting up means it’s probably something in the tuning then. Maybe….
Crank sensor acting up?

I ordered a new one, figured I’d I’m going through the hassle of pulling it might as well throw a new one in.

I once had this happened to a friend with a Gen3 , we disconnected the battery for a whole day to let the ECU drain out and of course cleared the codes before we removed the battery and it never came back, he had a whipple setup

I’ll give that a go. It’s pretty annoying, I’ve checked over everything but clearly missing something.

 

[scoobaru88]

Still chasing this. Link to a log is below - it idles normal, then at the end it acts up and dies. Not sure if anyone can look at the log and see if they notice anything.
Dealer had it for a week and all they said was the throttle pedal was no good, they replaced it with no change. Still just misfires and random stalling at idle, throttle and driving its fine with no misfires above 2k rpms.

https://ufile.io/5rb43yji

wouldn't let me attach it since its a hptuner file. Suggestions or ideas?

 

[scoobaru88]

Update - Had VCT solenoids, cam phasers replaced. Smoke tested (no leaks), compression test (all cyls were good), leak down test (all were good), new crank sensor, Crank relearn, new o2 sensors, new MAF, new port and direct injectors, new fuel pumps, new fuel pressure regulators. Threw on a Boss intake thinking maybe the IMRC were bad.

Been to a couple different shops, none can figure it out. Dealer said it was throttle pedal so they replaced that with no change (not sure how they came to that conclusion).

Still shows Cyl4 and 3 being highest misfire counts.

 

[Guusgeluk]

In my case, Mustang GT 2021, annoying engine stuttering around 1300/1500 rpm under load, but no codes. Using forscan mode 6 i found some misfires in cilinder 5 only. It appeaed to be a faulty coil. Hope this helps others (only 28k Km).

 

[Guusgeluk]

Update - Had VCT solenoids, cam phasers replaced. Smoke tested (no leaks), compression test (all cyls were good), leak down test (all were good), new crank sensor, Crank relearn, new o2 sensors, new MAF, new port and direct injectors, new fuel pumps, new fuel pressure regulators. Threw on a Boss intake thinking maybe the IMRC were bad.

Been to a couple different shops, none can figure it out. Dealer said it was throttle pedal so they replaced that with no change (not sure how they came to that conclusion).

Still shows Cyl4 and 3 being highest misfire counts.

Any new updates on stuttering at low rpm? All sparkplugs and 1 coil replaced, but no improvement and without DTC’s, but still misfires on nearly all cilinders (very annoying while driving). The shop mentioned it all has to do with 2 cilinder switch off…. I have doubts about that.

 

[mhunsr]

It could be the O2 sensors - either fouled or if you have extenders they can cause problems. I have had that happen on Shelby's.

 

[Guusgeluk]

It could be the O2 sensors - either fouled or if you have extenders they can cause problems. I have had that happen on Shelby's.

Could a faulty O2 sensor deliver parameters values within normal range? See pic.

My GT 2021 has no DTC’s, but i feel stuttering at low rpm’s under some acceleration load. Operating fine under higher rpms. Mode 6 see some misfires on all cilinders. My shop mention the cilinder shut of system could be tge culprit, but basically has no clue… car is still under warranty

 

[mhunsr]

I would not guess bad O2 sensors in your case. Do you have any vehicle modifications? What octane fuel do you use? Have you tried fuel system cleaner? (royal purple complete fuel system)

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