Mystery Misfires (p0300 went away by itself but $06 says otherwise)

[SensesFail]

So I’ve had an issue with p2004/p2005 and p0300 early on but p0300 went away on its own a week ago(?). I did an IMRC lockout on the intake manifold with a PBD tune and there’s been no check engine light since.

HOWEVER.

I like to look at all the diagnostic data because I’m paranoid since I got this car. In the photos are within 107 miles of driving,and there is a 12 minute difference between the two photos. I was just sitting, idling in a parking lot, not driving. Can someone please tell me if these types are values are normal, if they aren’t normal, what to do because I’ve been dealing with this for months, there’s no check engine light and no p03xx at all.

Please and thank you.

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[Cobra Jet]

I don’t know if you have seen the below 2 threads yet, it may offer some additional insight to the misfire question.


This thread may give some enlightenment to Ford's misfire strategies:
https://www.mustang6g.com/forums/threads/good-tech-article-on-ford’s-misfire-strategy.108076/

Also to note, this thread contains shop manual info about diagnosing the S550 misfires:
https://www.mustang6g.com/forums/threads/misfiring-even-after-replacing-coils.153240/#post-3124335

 

[SensesFail]

Update: was able to tune it out after trial and error

 

[Baldilox]

Update: was able to tune it out after trial and error

When you say you tunes it out. I’m assuming you mean PBD changed something in the tune and got the misfires to stop? If so, do you know what it was? I ran into the same thing with a Lund Tune. Thanks

 

[Torinate]

Same issues i've been dealing with...

Not sure if he meant the tune was actually changed or he's tuned them out like my wife tunes me out when I talk about something of no interest to her...

 

[SensesFail]

When you say you tunes it out. I’m assuming you mean PBD changed something in the tune and got the misfires to stop? If so, do you know what it was? I ran into the same thing with a Lund Tune. Thanks

Yeah I got her pre-owned with some obvious previous unknown mods so I was chasing after some CEL codes which included p0300 and a couple others. Turned out to be the intake manifold runners, so I locked out the IMRC. I originally was getting the tune done remotely then finally said 'F it' and went in person to get whatever kinks out, which they did.

 

[Biggus Dickus]

Yeah I got her pre-owned with some obvious previous unknown mods

When I read this I first thought you were talking about your wife.

 

[Baldilox]

Yeah I got her pre-owned with some obvious previous unknown mods so I was chasing after some CEL codes which included p0300 and a couple others. Turned out to be the intake manifold runners, so I locked out the IMRC. I originally was getting the tune done remotely then finally said 'F it' and went in person to get whatever kinks out, which they did.

Thanks for the reply. Unfortunately I don’t have a local tuner I trust to take the car to. Lund at this point has said that misfires are caused by mechanical parts on the car and there is nothing they can do about it. These issues started after locking out IMRCs, larger injectors, VMP BaP and Lund Tune. Mode 6 scanner is showing random misfires on most cylinders with one or two being quite a bit higher.

 

[SensesFail]

When I read this I first thought you were talking about your wife.

You technically aren't wrong

 

[SensesFail]

Thanks for the reply. Unfortunately I don’t have a local tuner I trust to take the car to. Lund at this point has said that misfires are caused by mechanical parts on the car and there is nothing they can do about it. These issues started after locking out IMRCs, larger injectors, VMP BaP and Lund Tune. Mode 6 scanner is showing random misfires on most cylinders with one or two being quite a bit higher.

Have you been watching your A/F? STFT and LTFTs? Are you running lean? I went as far and did a compression test out of paranoia.

 

[Baldilox]

Have you been watching your A/F? STFT and LTFTs? Are you running lean? I went as far and did a compression test out of paranoia.

Yeah everything looks good in the logs, Lund has verified. I think I may do a compression test as well. Currently pulled the intake back off to replace the intake manifold gaskets, waiting on those to show up.

 

[SensesFail]

Yeah everything looks good in the logs, Lund has verified. I think I may do a compression test as well. Currently pulled the intake back off to replace the intake manifold gaskets, waiting on those to show up.

Keep us updated

 

[noshine4mine]

Try a Crank re-learn. When I put my new engine back in I had misfires for days, did the re-learn and they stopped. HP Tuners VCM suite had the relearn available in the software. I had to get the OS ID from the tuner in order for it to be an option in the software.

 

[Torinate]

I’ve done multiple crank relearns- both through my nGauge and also Forscan without any success. I get the notification that says it’s complete but doesn’t change anything. No misfires during warm up when the idle is higher but once warm, they start. Maybe OP will have better success than what I’ve had.

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