Transmission Issue

[WIStingerGT]

Twice this week while accelerating from a stop in comfort and sport mode (auto shift not paddles), I accelerated hard and when shifting the transmission slammed back into first or wouldn't shift up, i couldnt tell. Revs went sky high. As soon as I backed off the gas it shifted into whatever gear it was looking for. I proceeded as normal without pushing it too much and it drove fine. Very concerning as it has never done this before and the speed from the line is the best things about this car.

Back story, 2019 gt awd, 15000 miles. I have already had to replace the spark plugs after the engine chewed them up (around 8k miles).

Any idea what this could mean? Common problem? Easy to fix? Should I be worried that my powertrain is a lemon?

Thank you in advance.

 

[Snicklefritz]

The only "good" thing about this story is that it is a drivetrain issue, because that is the one warrantied area of the car to 100,000 miles. straight up if your drivetrain grenades it will be replaced. unless you have mods your not admitting that could complicate the warranty claim. question, what do you mean by "chewed up" spark plugs? I've had cracked plugs but only after well over 40,000 miles.

 

[WIStingerGT]

By chewed up I meant that 2 were cracked and had to be replaced. To note, it is 100% stock all the way and only use premium fuel. Have done 2 oil changes, both at dealer.

Both instances of the issue happened with Temps around 30 degrees F but I had been driving for over 10 minutes both times. Could it be the trans wasn't to temp yet?

 

[oddball]

My trans regularly act poorly when it's cold, but that's within the first two minutes or so of starting. It should be warm enough after 10 minutes even in cold weather.
It will likely be a dealer repair issue, so you'll have to make sure it can be easily reproduced and have good notes about what, exactly, is happening. e.g., is the car still in first trying to go to second? Is the trans still engaged or is it in neutral at that time and you're hitting the rev limiter?

There's a slight chance the trans fluid is low. Accelerating hard causes the fluid to rush to the back of the trans, but the pump pickup is normally towards the front. This can cause a lack of fluid supply, causing a line pressure drop, causing poor shifting or dis-engagement. Symptoms go away once the acceleration slows down as then the pump can pull the fluid. Only problem is there's not much of an opportunity for a transmission leak on these cars, and checking the level is annoying. So if this is the case then the first question is "where the hell did the fluid go?"

Seems unlikely to be a programming problem since you're stock. Could be the start of an internal failure on the trans but that's pretty unlikely. These have proven to be pretty reliable units.

A good data log from a mid-tier scan tool would be very revealing, but it's tough to spend $600+ to chase a single issue.

I would recommend replacing all the spark plugs. If two failed then it's likely the others are not far behind. The most common spark plug symptom is rough idle and massive misfire on hard acceleration though.

 

[WIStingerGT]

On another forum someone recommended checking out the low pressure fuel pump. Have you heard of that?

 

[oddball]

Nope. Not sure there is such a thing. There's an electric auxiliary pump, but that's part of the auto-stop system. It'll keep the trans circuits pressurized while the engine isn't running so the trans stay engaged and ready to go once the engine fires back up. Can't generate enough flow to actually feed the transmission, though. And it's only important when the engine is off due to the auto-stop.

 

[Snicklefritz]

Well that would never be a thing with my car since I kill ISG first thing upon starting the engine.