Rough acceleration when cold, why?

[Evil Minion]

Yes, I know it's been covered before, that it's normal for the GT (and maybe the others?) to feel a little rough on light accelerations when the engine is still cold.

I'm curious as to how, specifically. Is it something mechanical in the drivetrain? Is it tuned that way to try to not warp the heads if some idiot goes WOT before it's ready?...

Anyone have any knowledge as to what exactly that slightly rough, stumble-y, feeling is caused by?

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[astolt12]

The engine is protecting itself and you from blowing it up. Although these engines are modern it still doesn't mean the second you start it you should be going WOT and crack the throttle.

Let it warm up, keep the RPMs lower and in a short distance (about a half mile for me) its ready to go.

Only time i see someone needing to cold start a car and run the piss out of it is if there is a true emergency. Waking up late isnt a true emergency.

 

[lazarus870]

Every car I've owned has been like this.
I have a Toyota that when you hit a certain RPM jumps like 40 horsepower and engages the other cam (I think that's how it works).
It won't do this if the engine isn't warmed up. And that's 10 year old technology at least!

 

[ScottsGT]

My wife's Honda Pilot needs this technology. We live on a hill, and when we back out of the driveway we are heading up hill in the morning. She leaves about the time I'm getting out of bed at 6:15 am.
Every morning it sounds like a full throttle take off up the hill with her driving. I keep telling her to take it easy for the first mile, but I also tell her to quit washing our whites with other colors and she won't listen. It's a wife thing I guess.....

 

[Danger]

Yes these cars need to warm up. You can easily tell when you start it up first thing in the morning and the clutch feel is different. It's called operating temperature, every car has one, ford even gives you a nice gage to see your oil temp.

 

[Evil Minion]

The engine is protecting itself and you from blowing it up. Although these engines are modern it still doesn't mean the second you start it you should be going WOT and crack the throttle.

Let it warm up, keep the RPMs lower and in a short distance (about a half mile for me) its ready to go.

Only time i see someone needing to cold start a car and run the piss out of it is if there is a true emergency. Waking up late isnt a true emergency.

Maybe the "why" in my question was the wrong word used. I know why, I don't know how. Is it a tune thing? Kind of sounds like it, but you'd think they would have done it in such a way as to not feel broken. It's not a refined feeling at all...

And if it is tune related, can it be removed by tuning it? Not saying it should be, but can it be?

 

[Herr_Poopschitz]

My wife's Honda Pilot needs this technology. We live on a hill, and when we back out of the driveway we are heading up hill in the morning. She leaves about the time I'm getting out of bed at 6:15 am.
Every morning it sounds like a full throttle take off up the hill with her driving. I keep telling her to take it easy for the first mile, but I also tell her to quit washing our whites with other colors and she won't listen. It's a wife thing I guess.....

Gotta pick your battles. Just be happy she does your laundry at all!

 

[UglyMutt]

I have noticed this same feeling in my car. Its odd. When its cold and you even lightly apply throttle to accelerate it just isn't smooth. It stutters a bit or almost feels like a misfire.

I kinda think its the charge motion control valves being a little confused with a cold block and cold intake track but regular ambient intake air temps along with running rich to heat up the cats with the cams phased to blow fuel out again, heating up the cats.

I think all that happening makes for inconsistent throttle input response. Its not great but I get it.

I don't really let my cars sit to warm up in normal temperatures. Worst thing for a engine is operating cold and the way to keep a car the coldest, longest is to let it sit and idle. Just get in, start, put on your seat belt and go. I just keep the throttle light and don't labor the engine.

 

[RidetechJosh]

I keep telling her to take it easy for the first mile, but I also tell her to quit washing our whites with other colors and she won't listen. It's a wife thing I guess.....

Lol, I was dying on this one... :cheers:

 

[Evil Minion]

I have noticed this same feeling in my car. Its odd. When its cold and you even lightly apply throttle to accelerate it just isn't smooth. It stutters a bit or almost feels like a misfire.

I kinda think its the charge motion control valves being a little confused with a cold block and cold intake track but regular ambient intake air temps along with running rich to heat up the cats with the cams phased to blow fuel out again, heating up the cats.

I think all that happening makes for inconsistent throttle input response. Its not great but I get it.

I don't really let my cars sit to warm up in normal temperatures. Worst thing for a engine is operating cold and the way to keep a car the coldest, longest is to let it sit and idle. Just get in, start, put on your seat belt and go. I just keep the throttle light and don't labor the engine.

Yep, that's the exact feeling, and I do the same when warming it up. Got to get it moving in order to warm up the tranny and diff, not just the engine.

I wonder if anyone can find anything obvious in the stock tune file where it's doing something with ignition or cam timing when the heads and oil are cold.

 

[McCarthy]

Almost all cars do this. I keep my RPM very low until it's fully warmed up, and it is rough until then.

Nothing is harder on a motor than starting it up and going full throttle instantly. I have a few co-workers who start the car for the first time in eight hours, and proceed to leave strips going up the hill from the office. Interestingly enough both of their cars burn oil faster than gas and generally run like shit.

 

[RoadDog]

How do you feel after jumping out of bed 1st thing in the morning?
Ready to run a 10K, at full steam, immediately?
Are your tolerances around .0010?
And the software folks are always blaming it on the hardware folks - what are you going to do about that?
You don't need to hear it from me, but your motor is your heart. Love it, treat it well and it will give you lots of love in return.
After 20 miles, run the piss out of it.

 

[kenbidwell]

I understand the need to warm them up but I will have to say that my LS2 GTO that I traded in for my GT was smooth from start to finish. Never hesitated even when cold. I thought we left the cold stumbles behind when we went to fuel injection, guess not!

 

[madweazl]

Eh? Normal? You guys are joking right? My '12 Mustang didnt do any of this shit. Nor did the 15 cars that preceded it. After flashing the SCT preloaded 93 octane tune all of this bullshit went away. Not sure what or why ANY of you are thinking this is "normal" or acceptable but it certainly is not. Nothing is being "protected." It's a shit tune out of the box and it should have been corrected before release. The base Lund tune does it as well but to a lesser extent. I imagine after they get all of the idle, short drive, and 4th gear pull that it starts to get sorted but to think this is normal or a feature is crap.

 

[DivineStrike]

Hate on the oem all ya want but I'd attribute it to running richer until it gets up to operating temp. Not sure if ii can say I've really experienced it. Guess I don't care as I'm not running it hard until it's warmed up

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