2015 GT: Midrange stutter/stumble issue

[MoneyPit#53]

Like the title reads. Bone stock manual, 3.31 gears, non PP, 93 oct, about 700 miles on the odometer. Pretty noticeable stumble/stutter during light to half throttle when approaching 2800-3400 RPM. Stumble/stutter is non-existent during WOT pulls. No check engine or warning lights. I have no way to data log, just curious if anyone else has ever experienced or heard of this type of thing before. :shrug:

Comments, suggestions, opinions.......

PS: I've had a handful of blown S197 coyotes in the past 4 years, but the S550 is new to me.

-Nick

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[SnoopisTDI]

My GTPP does the same. I've seen it mentioned by a few others as well. I guess it's "normal" although I've never seen an explanation and not every car does it.

 

[Charles147]

wild guess but sounds like it's the variable cam timing doing its thing...

 

[MoneyPit#53]

My GTPP does the same. I've seen it mentioned by a few others as well. I guess it's "normal" although I've never seen an explanation and not every car does it.

I've seen a few guys mention this very characteristic as well but they were posting about in the forced induction section. I did a pretty through search but didn't get any hits on this happening on a bone stock car besides you stating yours does it as well.

wild guess but sounds like it's the variable cam timing doing its thing...

From the few posts I have seen. The stuttering/stumble I am seeing sounds exactly like the issue the forced induction guys are having with the IMRC's being mapped to function at certain RPM's vs pre mapped throttle percentage settings.

Just seems weird that I have probably one of the later '15 models and there aren't too many reported cases of these stumble behavior.

 

[ScottsGT]

Mines temperamental like that when cold. Once warmed up, slick as snot on a door knob.

 

[BBB]

only when cold

 

[P4RKER]

Mine does this as well if I drive before my oil temp is in the "normal" range. Once heated up though it goes away.

 

[dubster99]

Mine also does it when cold. I also assume it's the IMRCs doing their thing in that range causing a stutter/surge.

 

[MoneyPit#53]

Mine also does it when cold. I also assume it's the IMRCs doing their thing in that range causing a stutter/surge.

Weird how mine does it regardless of the engine/oil temp.

 

[whalesalad]

Just want to chime in that my car does this as well. It only has 200 miles on it. I notice it around 1800-2200 rpm usually when going from very slight throttle at cruising speed to get on it to pass someone.

I chalk it up to the variable valve timing but indeed wish it was smoother. Next time I will pay more attention to engine and oil temp.

TBH if this is normal I don't really mind ... but I bought the car with 65 miles on it so was kinda worried that someone beat on it while it was cold during a test drive and warped something.

 

[vinnie_febs]

Mine does the exact same thing. It might be normal because I really don't notice it when driving in "Sport" mode. My car is just over two weeks old.

 

[Varekai]

Mine also does this, 3.31 base model, lund tuned, but only in third gear under mild acceleration. When it hits that range in third gear it's like the engine isn't sure what it wants to do. Can't replicate it in any other gear.

 

[dfrost]

Mine as well, only when CHT is below 180°f. Only takes a few miles to warm up and then smooth as can be. :shrug:

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