Stuttering during track day on sport mode

[JN66]

Hey fellas -

Just finished the third session of the day (20 minute sessions) and I had to come in early due to the car hesitating and stuttering when I got hard on the gas after about 15 minutes or so. In 2nd and 3rd.

Any suggestions or ideas?

Power would start to go then it felt like I was taking my foot off the gas, then t would go again. Like a bucking bronco.

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[MCarsFan]

Hey fellas -

Just finished the third session of the day (20 minute sessions) and I had to come in early due to the car hesitating and stuttering when I got hard on the gas after about 15 minutes or so. In 2nd and 3rd.

Any suggestions or ideas?

Power would start to go then it felt like I was taking my foot off the gas, then t would go again. Like a bucking bronco.

Check your coil packs

 

[The Chairman]

Hey fellas -

Just finished the third session of the day (20 minute sessions) and I had to come in early due to the car hesitating and stuttering when I got hard on the gas after about 15 minutes or so. In 2nd and 3rd.

Any suggestions or ideas?

Power would start to go then it felt like I was taking my foot off the gas, then t would go again. Like a bucking bronco.

Was traction control turned off? If not, the car will do all sorts of things to keep the rear wheels turning, avoiding slippage: Clamps the rear brakes, takes out timing, seems like fuel shut off.
Also, when you hit the rev limiter, it has the same effect you are feeling. If you blow past the limit, it gets real quiet.... Then it catches again as the revs come back down. Been there...
BTW: If you have set a MyKey and are using it, it may have some funky settings.

 

[The Chairman]

BTW#2: I presume you have over 500 miles on it? There are some settings that control revs, etc. until some preset number of miles. Don't recall what that number is.

 

[firestarter2]

Where you running out of gas? on the track at like a 1/4 you will start to hesitate

 

[JN66]

Thanks fellas.

Half tank of gas.

No idea what a Mykey is (pretty sure I haven't set it).

I left traction control on. Just basic sport mode.

Car was getting pretty hot. It was very strange. It did feel like the fuel kept getting slashed 'on, off, on off, etc).

Definitely felt what happens once you redline it - expected that though from previous track days.

 

[16GT350]

I agree with what was already said. Likely traction control. I had it do something very similar to me on track. I always run in Track mode on track (unless I forget). When I run in sport mode on the street I turn off traction control. It impacts the acceleration all the time even when I don't sense much wheel spin, etc.

 

[JN66]

I would be surprised if it had anything to do with traction control. Only was happening when the car was running quite hot. Didn't do it at all in the first 15 of the session(s).

I'll take it in. See if I get can any codes from it. Give the whole thing a solid once over.

 

[xXANCHORMONXx]

If you have a scan tool check for pending codes.

 

[xt6wagon]

If the traction control is working at the track the rear end should start to feel "greasy". The stability control is also pretty smooth up till it thinks you are on a mission to find a tree or wall with the back of the car. That gets a bit abusive when it hits that mode.

That said, with 1/2 a tank of gas you might be having issues as its possible to lose quite a bit of usable gas if you are sloshing it around over and above what mere side loading should account for. My SHO was reading a 1/4 tank on the track, get to the gas station and it only takes a few gallons before its full. Whats really weird is the only car I've owned that had a surge fuel tank/pump that solves these issues was a Topaz AWD. 100hp 3spd auto car gets something a 526hp track monster doesn't... Lol.

Course race cars use nice foam filled fuel cells that don't let the fuel slosh around and thus life is good for them.

 

[JN66]

If the traction control is working at the track the rear end should start to feel "greasy". The stability control is also pretty smooth up till it thinks you are on a mission to find a tree or wall with the back of the car. That gets a bit abusive when it hits that mode.

That said, with 1/2 a tank of gas you might be having issues as its possible to lose quite a bit of usable gas if you are sloshing it around over and above what mere side loading should account for. My SHO was reading a 1/4 tank on the track, get to the gas station and it only takes a few gallons before its full. Whats really weird is the only car I've owned that had a surge fuel tank/pump that solves these issues was a Topaz AWD. 100hp 3spd auto car gets something a 526hp track monster doesn't... Lol.

Course race cars use nice foam filled fuel cells that don't let the fuel slosh around and thus life is good for them.

This is actually interesting and you could be on to something. I remember when I left the track I was looking at the KM available to me and it was somewhere around 100km. Which would put me at less than half as a full tank usually says 280km.

I'm heading in for a full once over to the shop and I'm out again in a few weeks. I'll make sure I fill up between sessions just to see.

 

[The Chairman]

I would be surprised if it had anything to do with traction control. Only was happening when the car was running quite hot. Didn't do it at all in the first 15 of the session(s).

When your head and tires get warmed up, you can get more aggressive. So you may be hitting traction control more than you would earlier in the run.
You also noted using 2nd gear which really emphasizes the torque. I don't recall getting below 3rd on track. But most of the tracks here in TX are pretty fast. So we tend to run 3rd and 4th, hitting 5th on the longer straights.
I also leave TC on for the first few laps while in Sport mode. Then turn off the TC once my tires and head are warmed up.

 

[JN66]

When your head and tires get warmed up, you can get more aggressive. So you may be hitting traction control more than you would earlier in the run.
You also noted using 2nd gear which really emphasizes the torque. I don't recall getting below 3rd on track. But most of the tracks here in TX are pretty fast. So we tend to run 3rd and 4th, hitting 5th on the longer straights.
I also leave TC on for the first few laps while in Sport mode. Then turn off the TC once my tires and head are warmed up.

Thanks for the response.

The track I was at (Mission, BC) is pretty short and incredibly rough. 9 turns only and they are quick and in succession. I could hit 4th on the small straight but only for a few seconds.

I'll try running in track mode or turning traction off - although I am not sure how to turn it off.

 

[funkbrotherj]

JN66

I've had this same issue for a couple months now. I've never tracked mine and it doesn't get hot. I've taken it to the dealership a couple of times now but they say they can't feel it. I know they're just not used to the car. It's a really annoying problem. Mine will happen driving along on the highway and it feels like the fuel delivery is an issue maybe. It honestly feels like someone is grabbing the car.

 

[BlkGT3]

Depending on the track you can fuel starve at a little less then 1/2 tank. I also hazard a guess it was Sport mode if you were trying to carry to much slip angle, especially if you left TC on.

Peter

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