Misfire Counts On All Cylinders

[Basspro302]

Hard to diag some thing like this without actually seeing the car, but im leaning towards a crankshaft sensor issue. Most likely the tone wheel is jacked up. Since it had a clutch installed. You would need a oscilloscope and probe the crank signal. I have ran into it on other types of cars and it never triggered a crankshaft position sensor code or timing correlation code. The truck i ran into that issue was a ford ranger where the trigger was bent causing the air gap to change, and it would randomly misfire then run good. It may be hard to catch if you aren’t familiar with cam/crank waveforms. Having a known good to compare it to will be helpful.

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[Fat_Joe]

New plugs. Cleaned injectors, smoke test x2, cleaned MAF, new TB, switched coils around x4, compression test, scoped the cylinders, KAM reset x3, crank relearn x4, numerous logs and mode 6 data.

Nothing makes sense. Misfires galore at idle. Nothing under strain when it is more likely too. I did see one during a pull in a log though. No cels. Lamda is excellent. STFT are fine. Same as when initial logs were done.

I do here small pops idling and have had some backfires on decel. I’m out of options as well. Was hoping the VCTs did it for you then I would have given them a go.

Well we got two things in common. A 2016 mustang and misfires for no apparent reason. I am pleasantly surprised you did all that but yet haven’t found the issue. Then again, I’ve done pretty much what you have except a new throttle body which crossed my mind at one point. This is honestly a pain for both of us

 

[Torinate]

Yes it is. Weather is getting cooler and there’s a few track rentals coming up. But I don’t want to take it with the misfires happening for fear of hurting something. Very frustrating. Lots of smart people on here and from reading so many posts, this seems to be common. Surprised there hasn’t been someone that can pinpoint it.

 

[Fat_Joe]

Yes it is. Weather is getting cooler and there’s a few track rentals coming up. But I don’t want to take it with the misfires happening for fear of hurting something. Very frustrating. Lots of smart people on here and from reading so many posts, this seems to be common. Surprised there hasn’t been someone that can pinpoint it.

I get that, I have full bolt ons and only put 379hp to the wheel. Something is not right. But then inlet temps were really high as I didn't connect the CAI right, It was pulling near 150F at a standstill and it was a very hot day. My fault 100%.

Either way, are you getting misfires on all cylinders, more on one bank? Have you looked at the flaps in the intake manifold?

 

[Torinate]

I get that, I have full bolt ons and only put 379hp to the wheel. Something is not right. But then inlet temps were really high as I didn't connect the CAI right, It was pulling near 150F at a standstill and it was a very hot day. My fault 100%.

Either way, are you getting misfires on all cylinders, more on one bank? Have you looked at the flaps in the intake manifold?

Misfires all over. Worse on a few different cylinders but spread out.
I have an Edelbrock Supercharger so no intake or IMRC to worry about.

 

[Fat_Joe]

Misfires all over. Worse on a few different cylinders but spread out.
I have an Edelbrock Supercharger so no intake or IMRC to worry about.

Dang, yeah we do have the same problems. I was thinking imrcs but you don’t have any. How long has this been going on for you? Right after supercharger install? And under what conditions does it misfire? At idle every 20ish secs I have a cylinder misfire for mine. Car shakes and rpm drops under 600 for a sec. And then of course the highway misfires at part throttle cruising

 

[Soulja4187]

Dang, yeah we do have the same problems. I was thinking imrcs but you don’t have any. How long has this been going on for you? Right after supercharger install? And under what conditions does it misfire? At idle every 20ish secs I have a cylinder misfire for mine. Car shakes and rpm drops under 600 for a sec. And then of course the highway misfires at part throttle cruising

I think your issue could be a tune problem. Just like someone suggested I think you should get a different tuner like Wengerd

 

[Replicator]

Didn't read the entire thread but what feedback are you seeing from the wideband in terms of A/F ratio? Idle, Part throttle, WOT. This would give you an idea of the health of the tune you're running.

 

[Torinate]

Dang, yeah we do have the same problems. I was thinking imrcs but you don’t have any. How long has this been going on for you? Right after supercharger install? And under what conditions does it misfire? At idle every 20ish secs I have a cylinder misfire for mine. Car shakes and rpm drops under 600 for a sec. And then of course the highway misfires at part throttle cruising

Started this spring when I took it out of storage. Noticed it a little then got a little worse from then. Has been consistent all summer though. I have been through everything I know of but didn’t change out the VCT.

I’m tuned by Lund. Have had the blower for 3 years now. No track passes this year. Babied for the most part. Cruiser car basically.

Logs I’ve run have looked good. STFT are fine - on par with previous logs when first done and the last couple summers. Car is stored in my heated garage. All wiring looks factory new. Checked grounds everywhere and they’re fine. No cels ever so the car doesn’t know it has an issue.

I do get a little popping at idle every now and again and watching mode 6 those are the actual misfires. So if can timing was off, could cause it. 99% of my misfires are at idle or when off the gas and coming to a stop. On occasion it will backfire then. Just once so it a “burble” type thing. Just a louder pop. So timing or extra fuel perhaps?

 

[Fat_Joe]

Started this spring when I took it out of storage. Noticed it a little then got a little worse from then. Has been consistent all summer though. I have been through everything I know of but didn’t change out the VCT.

I’m tuned by Lund. Have had the blower for 3 years now. No track passes this year. Babied for the most part. Cruiser car basically.

Logs I’ve run have looked good. STFT are fine - on par with previous logs when first done and the last couple summers. Car is stored in my heated garage. All wiring looks factory new. Checked grounds everywhere and they’re fine. No cels ever so the car doesn’t know it has an issue.

I do get a little popping at idle every now and again and watching mode 6 those are the actual misfires. So if can timing was off, could cause it. 99% of my misfires are at idle or when off the gas and coming to a stop. On occasion it will backfire then. Just once so it a “burble” type thing. Just a louder pop. So timing or extra fuel perhaps?

Hmmm did you happen to install an after market fuel pump or mess with the fuel pump in any way? Maybe something like a fuel pump is going out

 

[Torinate]

Stock pump with BAP. Lambda runs what’s commanded and doesn’t fall off. No fueling issues that I can see.

 

[Jackson1320]

It's been through 3 shops already and 2 tuners. The mystery still goes on. I hooked up forscan and manually turned on the imrc's And I could see them open and close along with the short fuel trims on both banks go up and down depending on whether they were open or not. (They go up when the imrc's are open and back down when I close them via forscan) So they appear to be working correctly, unless they are not closing all the way??? But the same misfire issue would happen on the old intake manifold.

this is not the same as locking them out. if you just refuse to take advise then why do u ask for it?

 

[Fat_Joe]

Little update: My car was at the ford performance shop for nearly a month. In the end, they couldn't find what was wrong with it. They were able to reproduce the misfires by fluttering the gas pedal but deemed that as irregular driving. They said they could only read so much off the car because it is tuned. They pretty much told me not to worry about it as it happens intermittently and it's not damaging the engine. And mentioned that the only person that will be able to fully diagnose it would be the one who tuned the car. I might go with a different tuner next year such as Lund. I have tired a local tuner and VMP but the issue still persisted. At this point I may just drive the car as is for a bit

 

[Torinate]

Little update: My car was at the ford performance shop for nearly a month. In the end, they couldn't find what was wrong with it. They were able to reproduce the misfires by fluttering the gas pedal but deemed that as irregular driving. They said they could only read so much off the car because it is tuned. They pretty much told me not to worry about it as it happens intermittently and it's not damaging the engine. And mentioned that the only person that will be able to fully diagnose it would be the one who tuned the car. I might go with a different tuner next year such as Lund. I have tired a local tuner and VMP but the issue still persisted. At this point I may just drive the car as is for a bit

I hear you.

That's what I ended up doing the last month and a half. I've been holding off putting the car away for the winter as the weather has been nice. My plan is to start earlier in the spring before I take it out and maybe start throwing parts at it, It's bad enough that even my wife says it has a problem when it pops (usually just once though) on decel. I keep telling her - I know there's a problem, but the car doesn't know there's an issue as it's never thrown a code. Nothing stored. No blinking light no nothing. I did do a couple of long logs the other night and will go through them when the car is away just to see if I can pick anything up. My plan will be to start again with a compression test first and re-double check lol. Then pull the injectors again and send them to be cleaned and flow tested. Then replace the evap. If still no change then likely IMRC and coils (although moving them around didn't change anything).

Beyond that, start with a new tune? Not sure. My off-idle hesitation is extremely annoying!!

I keep thinking there has to be something that's been overlooked...

 

[Fat_Joe]

I hear you.

That's what I ended up doing the last month and a half. I've been holding off putting the car away for the winter as the weather has been nice. My plan is to start earlier in the spring before I take it out and maybe start throwing parts at it, It's bad enough that even my wife says it has a problem when it pops (usually just once though) on decel. I keep telling her - I know there's a problem, but the car doesn't know there's an issue as it's never thrown a code. Nothing stored. No blinking light no nothing. I did do a couple of long logs the other night and will go through them when the car is away just to see if I can pick anything up. My plan will be to start again with a compression test first and re-double check lol. Then pull the injectors again and send them to be cleaned and flow tested. Then replace the evap. If still no change then likely IMRC and coils (although moving them around didn't change anything).

Beyond that, start with a new tune? Not sure. My off-idle hesitation is extremely annoying!!

I keep thinking there has to be something that's been overlooked...

Right, it's been a ride for sure. Keep my updated on how it goes with yours. I see a couple other people have the same issue on different forums but no resolutions. I also replaced the PCV valve and MAF sensor. But they are still there. Might run a seafoam spray through the intake and see if it cleans up a little. I need to get a catch can because I noticed oil accumulates fast around the intake (Hopefully it accumulates less with the new pcv valve).

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