2017 GT350 Cutting Out On Track

[11GT50]

Over the last two track days (Saturday and this afternoon) my car has started cutting out. It's fine on the out lap and the first two or three hot laps but then gradually starts cutting out and I end up parking it about half way through the session. By the end of today I made it two and a half laps and barely managed to get it back to the pits. It didn't show a CEL until the last session and that was a flashing P0300 in Track Addict - but that code is not currently stored and did not show up by the time I got home to read the code with my computer. The problem is, it drove home just fine and I can wring it out on the street and not replicate the problem. So far this is only occurring on track and after the car has some heat in it. At this point I don't think it will do any good to take it to a dealer. How in the world do I troubleshoot this?

Short video clip:

 

[Casultenbeers]

I will share my current experience with my GT350 issues that at first were only apparent while on track. Long story short, I’m dealing with P0014 & P0013 codes (VCT problems). The car would drive fine on the street. I have since narrowed it down to a wiring issue. It took a lot of pulls and hard driving to recreate the condition off track. (Idles like a cammed LS when showing symptoms). Checking for pending DTCs that haven’t illuminated a CEL is your friend in this situation. I used ForScan, once I had recreated my rough idle conditions and confirmed the pending DTC I went to the dealer and got very lucky to go through all of this with a Ford technician. When we looked at stored codes again it also showed a P0300 with my P0013. Misfire in Cyl #2. Clearly my cam timing problem is related to this. We will be replacing the cam actuator pig tails. Now my story as it relates to your situation, in my case the dealer was helpful. Solely due to the awesome technician I got to speak with and go through the car. He showed me the live data of my fuel trims and EQ. Basically what my engine was doing in real time. My advice would be to put hands on the engine harness and connectors. Make sure they are all secure for one, and believe it or not, wiggling the harness and connectors is how we isolated the problem in my case. These cars are known to have weak engine harnesses and wiring etc. Take a look at some of the HoneyBadger’s content for more on that. Long post but I hope it helps in some way and you get back on track soon.

 

[11GT50]

Thank you. That is very good information. Now that you mention it I do remember reading something about the engine harness in one of his posts. I'll see if I can dig it up.

Maybe @honeybadger will chime in? @JAJ shared a TSB on another forum regarding a loose output shaft nut causing an intermittent stumble so that's on my list to inspect as well.

 

[AdmirC]

Wow that sounded brutal, lots of misfires. Did you check the basics like plugs and such? Also ignition coils don't like heat and can fail sometimes when they get very hot but be fine otherwise. Usually not on all cylinders and they will flag a specific cylinder misfire code or a coil circuit code but still worth it to check them. Good luck.

 

[honeybadger]

Thank you. That is very good information. Now that you mention it I do remember reading something about the engine harness in one of his posts. I'll see if I can dig it up.

Maybe @honeybadger will chime in? @JAJ shared a TSB on another forum regarding a loose output shaft nut causing an intermittent stumble so that's on my list to inspect as well.

I know we chatted a bit elsewhere. Curious to hear where this leads ya'. Hopefully it's just something simple.

 

[Tonymustang302]

injector connectors too

 

[11GT50]

A quick update.

The car has started to intermittently cut out under moderate throttle while driving at street legal speeds. This evening I put the car on the lift to inspect the output shaft per the TSB posted by @JAJ on another forum. While the flange itself appears to be a press fit, the retaining nut was quite loose and likely had less than 30 ft-lb of torque on it. I removed the nut, cleaned the threads on the nut and shaft, added Loctite to the threads and torqued the nut to 105 ft-lb as called for in the service manual. I should be able to get the car out for an extended test drive tomorrow evening.

I'll drive it for a bit and to see if this fixes this issue before moving on to other suggestions.

 

[11GT50]

This did not resolve the issue. It still misfires when the engine is warm and at moderate RPM throttle tip-in. I drove around logging data with HP Tuners and found that fuel pressure is momentarily dropping to 0. I'll hook it up to Forscan tomorrow.

 

[PatientZero]

This did not resolve the issue. It still misfires when the engine is warm and at moderate RPM throttle tip-in. I drove around logging data with HP Tuners and found that fuel pressure is momentarily dropping to 0. I'll hook it up to Forscan tomorrow.

That would definitely cause issues, is the pressure sensor easy to replace? I'd try that before trying to replace the pump.

 

[honeybadger]

This did not resolve the issue. It still misfires when the engine is warm and at moderate RPM throttle tip-in. I drove around logging data with HP Tuners and found that fuel pressure is momentarily dropping to 0. I'll hook it up to Forscan tomorrow.

check the fuel pressure sensor on the rail. Check the wires and see if it’s fatigued. I had one fail on my original harness. I got a code, but similar experiences otherwise.

 

[11GT50]

It appears to be a wiring harness issue. I can move the wires at the end of the connector and watch the voltage go from 3v to 0v and back 3v and has a P0192 stored.

 

[TMSBOSS]

Warranty???

 

[11GT50]

I'm expecting it will be. I'm dropping it off Friday afternoon for an appointment Monday.

 

[VUDU V8 Steve]

Lemon law it back to mother Ford and start over- That's what I did, after 6 month long electrical nightmare, 16 trips to two stealerships, etc, etc..My second, a 2018 GT350 is dialed, no problems yet- but I will sell when 2 years 11 months old- I like Lemon Law/full Warranty protection- and I don't have your knowledge and trouble shooting ability! I hope it works out- such a fun track car when it behaves...

 

[11GT50]

Car is back from the dealer with a brand new engine harness courtesy of Ford Motor Company. Wiring to the fuel pressure sensor looks noticeably larger too.

Lemon law it back to mother Ford and start over- That's what I did, after 6 month long electrical nightmare, 16 trips to two stealerships, etc, etc..My second, a 2018 GT350 is dialed, no problems yet- but I will sell when 2 years 11 months old- I like Lemon Law/full Warranty protection- and I don't have your knowledge and trouble shooting ability! I hope it works out- such a fun track car when it behaves...

Nope, not doing that. I troubleshot and pretty much knew the problem ahead of time. Not worth the time and effort to Lemon Law it over something like that. It wouldn't be eligible for it anyway.

 

[nordique14]

Any update on if the dealer fix solved the issue? I just experienced what is likely the same issue. Intermittent hesitation (and cannot set cruise control). But in my case, no stored error code or warning lights.

 

[11GT50]

So far so no issues. It's only been on track one day since the repair but it ran well enough to set personal best a couple times. I'm satisfied.

If you have any scanning software you can measure the signal voltage and manipulate the wires at the connector to see if voltage falls to zero. You can also see it on a test drive as well.

There's also a TSB for the transmission tailshaft nut backing off that can apparently cause similar issues. Mine was only at around 35 ft-lbs when I checked it. Spec is something like 105 ft-lbs. I just cleaned the threads, added some Loctite and retorqued it.

It turns out it wasn't a complete harness though, they just replaced the pigtail.