2021 S550 GT struggling to start on cold days

[Tofuflower]

Good day,

I have a 2021 mustang gt, 12000km.
This morning on a cold start, the car is seriously struggling, It's only -10 C in my garage. The rev counter is just going up and down, the vacuum gauge is not stable at all, the car shakes while it does that, and the engine sound is not right as well. After about 2 tries of 1 minute each, shut it off and start again, the car is back to normal. I suspect that the engine warmed up slightly and is back to normal.

I have a video about it, see attached.
Any1 experiencing this? It doesn't happen all the time, only occasionally on colder days.

Thanks,

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[joe603]

I haven't seen/heard that before...I'd try an ECU reset by pulling the neg battery cable and let it sit for 10-15 min. Have you cleaned/replaced the air filter? That may help smooth it out. Highly recommend the K&N replacement vs a CAI.

 

[Tofuflower]

I haven't seen/heard that before...I'd try an ECU reset by pulling the neg battery cable and let it sit for 10-15 min. Have you cleaned/replaced the air filter? That may help smooth it out. Highly recommend the K&N replacement vs a CAI.

Thanks! the ECU was reset recently. I will grab a new air filter to see if that helps.

 

[MCS]

I'm also in Canada so feel your pain. It's felt like -21c here near Toronto.

Is your vehicle modded at all? I know that when I had my supercharger installed there was a bad plug that was causing all kinds of issues until it was replaced.

 

[EFI]

Check all connections to the airbox and air tube for any vacuum leaks.

 

[Tofuflower]

I'm also in Canada so feel your pain. It's felt like -21c here near Toronto.

Is your vehicle modded at all? I know that when I had my supercharger installed there was a bad plug that was causing all kinds of issues until it was replaced.

Nop. all stock. it's -10 in the garage, but -25 outdoors. Canada is too cold for these cars.

 

[MCS]

Nop. all stock. it's -10 in the garage, but -25 outdoors. Canada is too cold for these cars.

Nawwww, not at all. A million things can go wrong due to the cold sure but I see a ton of Mustangs driving around in the winter. I drove mine through last winter (with proper tires) before the SC was installed.

Definitely related to the cold though if, after a warmup period, it goes back to normal. I would call the dealership you bought it from and have them inspect it.

 

[ajsfirehawk]

Agree with EFI and I'd pull codes to see if you have any soft error codes that can help point you to the problem.

 

[Tofuflower]

Check all connections to the airbox and air tube for any vacuum leaks.

thx, I will check that. but how would that explain the fact that it only does this when it's cold and back to normal after a couple of tries?

 

[EFI]

thx, I will check that. but how would that explain the fact that it only does this when it's cold and back to normal after a couple of tries?

It doesn't really, but could be a connection is loose when cold then as things expand with heat it makes a better seal.

Are you getting any codes? You should try to have it scanned as it might narrow it down to something more specific.

Also is there a specific temperature when it does this? Like say when it's closer or right above 0* does it still do it?

 

[Tofuflower]

It doesn't really, but could be a connection is loose when cold then as things expand with heat it makes a better seal.

Are you getting any codes? You should try to have it scanned as it might narrow it down to something more specific.

Also is there a specific temperature when it does this? Like say when it's closer or right above 0* does it still do it?

I see. I just checked the code, no error. But I do see 2 of my cylinder misfiring in the log, which caused the scenario in the video.. It happened to me twice so far (the last time this happened and this time were different cylinders), both on cold days around -10 in the garage. Back to the dealer I go..
Log:
Misfire counts for last/current driving cycles(calculated) - Misfire Cylinder 1 Data
Max: 65,535Count Min: 0Count
Test result value: 1Count

Misfire counts for last/current driving cycles(calculated) - Misfire Cylinder 5 Data
Max: 65,535Count Min: 0Count
Test result value: 1Count

EWMA Misfire counts (average) for last 10 drive cycles - Misfire Cylinder 6 Data
Max: 65,535Count Min: 0Count
Test result value: 1Count
PASS

EWMA Misfire counts (average) for last 10 drive cycles - Misfire Cylinder 7 Data
Max: 65,535Count Min: 0Count
Test result value: 1Count

 

[Weyland-Yutani]

It doesn't really, but could be a connection is loose when cold then as things expand with heat it makes a better seal.

That, and soft parts would get more pliable with a little heat. I'm guessing even a teeny bit of unmetered air would make these motors fuss.

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