Misfire Counts On All Cylinders

[Fat_Joe]

Hello all!

Recently bought a 2016 Ford Mustang Gt Premium with 22k miles (now 28k). Been having misfire issues that showed up a month into ownership after I got more comfortable driving it as it's my first manual car. I have been encountering misfire codes for cylinders 1-6 with cylinder 4 having the most counts. (Mode 6 in Forscan). 7 and 8 also have counts in Forscan with 7 having the least amount out of all cylinders. The engine light will flash when I am cruising on the highway in top gear around 2k rpms. I also notice the car misfires with the ac on at idle every 30ish seconds it will have a drop in rpm. Talked to my tuner and all logs look good from what they can control. The tuner stated that most of the misfires are happening in bank 1 and they can't control specific banks like that. I was wondering if anyone has some insight on what could be causing something like this or even anyone who experience something similar. This has been my dream car that I finally was able to buy but it's been more of a headache then anything with these misfires. I would appreciate any help!

The mod list of the car is below:

• Roush CAI
• Roush catback with x pipe
• SolidPower Long Tube Headers (catted)
• Steed short throw shifter
• 47# Fuel Injectors
• 18 intake manifold with IMRC active
• McLoad clutch (Not sure which one)
• Tuned by VMP

Things I have tried with no luck

• New spark plugs, torqued down
• Swapped coil packs, still misfires mainly on cylinder 4
• New injectors
• New o2 upstream sensors
• New intake manifold (2018+), had the same issue with the original intake manifold
• Cleaned MAF and throttle body
• Went with a new tuner (VMP), originally tuned by a local tuner
• Retorqued everything under the hood and checked vacuum lines
• Crank Relearn and KAM reset
• Replaced crankshaft position sensor
• A different shop did a compression test and vacuum leak test. Everything looked good
• Took it to Ford and they couldn't figure it out (I don't think they really tried)

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[Jackson1320]

try locking out the imrc's

 

[Fat_Joe]

try locking out the imrc's

I was encountering the same misfires with the old intake manifold and the IMRCs were deemed working by a shop and I confirmed that by removing and checking if the rods were all still functional

 

[UhhhGoblin]

The IMRC actuators failed on my car. The shafts were fine, the valves moved by hand, but when commanded they didn’t go all the way to the closed position.

Not saying this is your issue, just that pushing the flappy-dos doesn’t necessarily rule out the IMRCs in troubleshooting.

 

[bankyf]

One really bad cylinder will absolutely register as misfires on every cylinder. I see it every day. Not saying that is your problem, but I wouldn’t dismiss the possibility. The bad cylinder will obviously be the one that is significantly higher.

Edit: just read your entire post again.Clearly I’ve been no help, lol. I wish you were local, I’d love the challenge. Either it’s the PCM or something was overlooked while doing the repairs/testing.

 

[Jackson1320]

smoke test it and lock out the imrc's. you can always turn them back on. it's just a test.

 

[Torinate]

I feel your pain man...

Watching in the hopes it get solved...

 

[Fat_Joe]

The IMRC actuators failed on my car. The shafts were fine, the valves moved by hand, but when commanded they didn’t go all the way to the closed position.

Not saying this is your issue, just that pushing the flappy-dos doesn’t necessarily rule out the IMRCs in troubleshooting.

That is so true. I originally thought it was the imrcs which is why I replaced the manifold in the first place with a 18+ manifold. But same thing happen on the new one

 

[Fat_Joe]

One really bad cylinder will absolutely register as misfires on every cylinder. I see it every day. Not saying that is your problem, but I wouldn’t dismiss the possibility. The bad cylinder will obviously be the one that is significantly higher.

Edit: just read your entire post again.Clearly I’ve been no help, lol. I wish you were local, I’d love the challenge. Either it’s the PCM or something was overlooked while doing the repairs/testing.

Yes, it’s been through a local tuner/service shop, ford’s performance shop, and it’s about to go to another shop this week. I am hoping someone can find out what’s wrong with it. I thought clogged cat but ford said no. And tuner said logs all look looked good. I had cat efficiency codes pop up but I put spacers on the downstream o2s. I am running long tubes with high flow cats so I heard it’s common. No extensions on the front o2 sensors, already removed them and replaced with longer o2 sensors lol

 

[Fat_Joe]

smoke test it and lock out the imrc's. you can always turn them back on. it's just a test.

That’s going to be my next step if this next shop still can’t figure it out. I am assuming I will need a new tune for locked out imrcs right?

 

[Torinate]

What codes does it show for the misfires? CEL on? I’ve got misfires all over as well but no CEL...

 

[Fat_Joe]

What codes does it show for the misfires? CEL on? I’ve got misfires all over as well but no CEL...

So far I got CEL with:
p0300
p0301
p0302
p0303
p0304
p0305
p0306

And P0420, P0430 at one point but put spacers on the downstream o2 sensors to take care of that

 

[Torinate]

Thanks.

Hope it gets figured out. So frustrating!

 

[stars_fan]

I would do another compression test. The tool is pretty cheap and it’s an easy process.

 

[Fat_Joe]

I would do another compression test. The tool is pretty cheap and it’s an easy process.

its in the shop right now, they are running through their own tests. Last I spoke with them, they are going to check the timing and pull out the spark plug for cylinder 4 to check compression of that cylinder since it has the most misfire counts

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