Acceleration not smooth when engine is cold?

[troverman]

I've noticed this about my 2020 GT with a manual...when its cold, like a minute or two after startup and I pull into traffic, I can't seem to smoothly give the car gas. It's like the engine starts to go, then backs off a second, which causes you to try to press the pedal more, which causes another lurch, and the process repeats a couple more times until you clutch and go to second. Is this just the nature of the electronic throttle with a cold engine? I'm giving it probably 1/4 to 1/3 throttle. I am in Sport mode, which I know makes the accelerator a bit more twitchy.

Anyone else have this? Makes me look like I don't know how to drive.

Sponsored

 

[Zathras]

I have the A10 with 3.55s, but sometimes I have a similar "bucking" issue, in the lower gears in Sport mode. Especially if I'm trying to accelerate over bumps or anything that may affect how much pressure my foot puts on the pedal. In my case I haven't noticed if it gets any better with temperature, because I don't normally use Sport mode until after the car warms up. (But in my case, it still can happen when warm.)

 

[ice445]

I get terrible rev hang for the first few minutes on a cold start. Lasts longer if it's actually cold outside. As long as you pay attention you can drive around it though.

 

[blue5.slow]

Completely normal

 

[Vlad Soare]

No, this is definitely not normal. The acceleration must be perfectly smooth at any temperature. I've never encountered the behaviour you're describing, not even at 10 °F.

Edit: I'm talking about a stock engine. If you're tuned, that's a different story.

 

[njweatherman]

On my 2020 mustang gt premium, automatic, the car is jumpy and has firm shifts when cold (sport+ mode). After about 5 to 10 minutes of driving, it goes away. BTW - my 2018 automatic Camaro did the same thing.

 

[2morrow]

Yeah I get this too. The bucking can get out of control if you let it but I'm always super smooth with throttle when cold.

 

[Vlad Soare]

On my 2020 mustang gt premium, automatic, the car is jumpy and has firm shifts when cold (sport+ mode). After about 5 to 10 minutes of driving, it goes away. BTW - my 2018 automatic Camaro did the same thing.

That's a gearbox thing. The automatic is known to behave oddly under some circumstances, and as far as I can tell people seem to consider it normal.
What the OP is describing seems to be something else. And the way he's describing it, it doesn't sound normal to me by any means.

 

[ICU812]

My guess is the direct injection, and cold slow moving air.
The air and fuel don't get mixed as well as it should, so much of the fuel is unburned and the o2 sensors try to tell the ecu to back off the fuel map, but the inlet air temp in the intake wants to tell the ecu, it is cold out add fuel. round and round we go, till it gets warmed up.

 

[MikeHTally]

No, this is definitely not normal. The acceleration must be perfectly smooth at any temperature. I've never encountered the behaviour you're describing, not even at 10 °F.

Edit: I'm talking about a stock engine. If you're tuned, that's a different story.

Yeah, definitely not normal. This day and time, the computer should deal with this.

 

[EFI]

No, this is definitely not normal.

It may not be "normal" in 2021, but it's a pretty common thing with the Mustangs especially the MT82.

OP I wouldn't worry about it, especially if it gets better with temperature. You have warranty, so you're covered if something goes wrong or if it gets worse (which it shouldn't).

 

[Vlad Soare]

It may not be "normal" in 2021, but it's a pretty common thing with the Mustangs especially the MT82.

My 2020 with MT-82 doesn't do it. The acceleration is perfectly smooth at any temperature, as soon as I start the engine.

 

[ice445]

My 2020 with MT-82 doesn't do it. The acceleration is perfectly smooth at any temperature, as soon as I start the engine.

So is mine, BUT the rev hang is atrocious. If I shift from 1-2, I have to wait twice as long to engage the clutch or it will buck. That's the only thing I can think of that OP may be experiencing. If the issue is that the throttle itself feels jerky, then I don't experience that.

 

[Vlad Soare]

There is a lot of rev hang, that's for sure. But most of it comes from the auto rev match. Disabling the ARM will cure it. Well, not exactly "cure", of course, but at least it will bring it down to a more acceptable level, which is more or less in line with other contemporary engines.
With the ARM on, the secret is to dump the clutch every time and - this is important - not to touch the gas pedal at all. You need absolutely no throttle at all while you're lifting the clutch. Only when the clutch is all the way up can you touch the gas pedal again. This is the exact opposite of good driving technique. If you train yourself to forget how to drive a manual properly, and to use the pedals like a rookie, it will be smooth as silk.

Sponsored