2020 5.0 misfires on track

[dsharek]

I have taken my 2020 Mustang GT PP1 on track at Carolina Motorsports Park twice now for full day HPDE events. Both days I have had flashing check engine light events where cylinders 5 and 6 severely misfire and turn off the cylinders. I scanned for codes and got misfires codes for 5 and 6 as well as the multiple cylinders misfire code. After the first track day I took the car to a dealership with 23,000 miles and was denied warranty and charged $340 to change the spark plugs. The dealership also told me that my warranty is voided due to taking my car on track. The misfires only occur at high load in third gear while on track. They happened with Costco 93 octane as well as track ethanol free 93 octane fuel. The car had the same 5 and 6 cylinders as well as multiple cylinders misfire codes on the second track day with the new spark plugs. Attached is an image of the plugs removed with 23,000 miles. The car is stock as far as I know. I have only upgraded the brake fluid and pads. I purchased the car used with 21,000 miles.

I have no idea why the ground straps are bent. The Ford tech claims they are bent due to my abuse and that is how they came out of the engine. Does anyone have any ideas on what to look for to resolve the very repeatable misfires while on track?

 

[KazarS197]

Welcome to TMO! Were you hitting the revlimiter or low on fuel, like below a quarter tank, when the cels came on?

Don't forget to do a car profile. I will create build thread.

https://trackmustangsonline.com/member-cars/categories/s550-mustangs.1/

 

[RES_22]

Looks lean....hot and dry.

 

[dsharek]

Looks lean....hot and dry.

Is there any way that my driving style would cause this? I am driving in sport + with traction control on. There is usually minimal traction control interference that I have noticed. Have you ever seen the ground electrodes bend off center from running lean? Thanks for the input. To me, this is a Ford tuning or hardware failure issue. The car misfires exactly the same with new plugs.

 

[RES_22]

Seen a lot of plugs but never a set damaged consistently like that.

Never seen that on OEM tune.

Are you certain that previous owner didn't leave a tune in place before sale?

 

[Scootsmcgreggor]

Since the misfire continues with new plugs try swapping coils. 1&2 with 5&6. See if the misfire follows the coils.

 

[dsharek]

Since the misfire continues with new plugs try swapping coils. 1&2 with 5&6. See if the misfire follows the coils.

Thanks. The dealer tech decided to do nothing since they couldn't duplicate the misfire on a test drive on my return visit. They were happy to charge me for spark plugs on the first visit without duplicating the fault.

Are you certain that previous owner didn't leave a tune in place before sale?

I am also curious if the car has an aftermarket tune. I was hoping the Ford tech would have been able to tell me that. I let them know that I bought it used and didn't know the history. They just told me that the mode 6 data showed misfires on all cylinders with 5 and 6 being the worst.

 

[o-man]

From reading this and your build post, try starting off with no less than 3/4 tank. I've run CMP before in a 2015 GT and a 2019 Bullitt. Ran the 2015 flat out of gas. The Bullitt will starve at about 3/8 of a tank, but has never set a missfire code

 

[blacksheep-1]

Damn dealerships are going to be the downfall of Ford Motor Company, Ford has warrantied all types of stuff, if it has a stock tune, and was driven in an HPDE event, it should be covered. I would call BS on this dealership, and reach out to Capaldi, Kohr or some other performance oriented dealership.

 

[BluPil]

only time I've had a misfire code on my 2019 is from hitting the Rev limiter.....

 

[TMSBOSS]

I have had good luck with dealerships. I agree, some do give the brand a bad name.
Do you have options? Other dealerships in your area?

 

[dsharek]

From reading this and your build post, try starting off with no less than 3/4 tank. I've run CMP before in a 2015 GT and a 2019 Bullitt. Ran the 2015 flat out of gas. The Bullitt will starve at about 3/8 of a tank, but has never set a missfire code

Thanks for the insight. It's odd that my 2020 gives misfire codes while others seem to just exhibit similar problems without the codes due to fuel starvation.

I have had good luck with dealerships. I agree, some do give the brand a bad name.
Do you have options? Other dealerships in your area?

I have several options in the Charlotte, NC area. Unfortunately, I am new to the area and Ford cars and don’t know if there is a service department willing to look into my issue. The root cause could just be fuel starvation. However, I got misfires at around 1G turns and with over a 1/2 tank of fuel on CMP nearly every session.

 

[Scootsmcgreggor]

Thanks for the insight. It's odd that my 2020 gives misfire codes while others seem to just exhibit similar problems without the codes due to fuel starvation.

I have several options in the Charlotte, NC area. Unfortunately, I am new to the area and Ford cars and don’t know if there is a service department willing to look into my issue. The root cause could just be fuel starvation. However, I got misfires at around 1G turns and with over a 1/2 tank of fuel on CMP nearly every session.

Was the noted starvation always during or soon after a long sweeping left? I’ve had it happen on mine above 1/2tank even.

 

[dsharek]

Was the noted starvation always during or soon after a long sweeping left? I’ve had it happen on mine above 1/2tank even.

It seemed to happen with over 1/2 a tank also. Nobody else seemed to get misfire codes or bent spark plugs from the starvation events. I believe I had starvation at some point, but there is likely also a tune or intake / vacuum problem also. I am looking for a different dealership that will look into the problem without being able to reproduce the situation.

 

[Nbjeeptj]

I have a 2019 and was getting misfire codes only while on track, from very early on. Just so happens it was also at CMP, although I am not suggesting it was that track causing it. I took it to the dealer several times and they could never reproduce the problem. I have an "HP tuner" and I did a crank relearn and have not had the problem since. May be worth a try if you are still looking for a fix.

 

[Mad Hatter]

Just in case, check out the state of the Crank sensor. A dirty sensor will give you the P0300 codes as well.

 

[blvckgt]

I have a 2019 and was getting misfire codes only while on track, from very early on. Just so happens it was also at CMP, although I am not suggesting it was that track causing it. I took it to the dealer several times and they could never reproduce the problem. I have an "HP tuner" and I did a crank relearn and have not had the problem since. May be worth a try if you are still looking for a fix.

I'm also experiencing misfire everytime I'm at the track pushing hard.
And same as you, dealer cannot reproduce the issue (Duh, since it only happens during full-send track sessions lol)
My powertrain is completely stock and I don't have any handheld tuner.
Is there any way I can crank relearn myself without going to the dealership?

Thanks!
P.S. I also bought fuel jugs after reading this post to keep my fuel tank completely full after each session and I still ran into the misfire during this past weekend.

 

[TMSBOSS]

Guys

When you are on track "Pushing Hard" are you bouncing off the rev limiter?

 

[blvckgt]

Guys

When you are on track "Pushing Hard" are you bouncing off the rev limiter?

With this in mind, this past weekend, I specifically never pushed over 7100rpm and short-shifted 6500rpm~7000rpm before the 7500rpm redline
But, I still ran into 2 misfires with 1 limp mode on Sunday.
Both times reset fine after shutting off the car and starting the engine back up

I tried short-shifting and keeping fuel completely filled every session and still got misfire.

 

[Scootsmcgreggor]

Yes you can do the misfire monitor relearn with Forscan.