ZLE engine laboring/stuttering under full throttle at track
 

Hello friends.
Hoping someone out there might have some information to help me sort out this problem.
My 2019 ZLE with 8k miles is giving me trouble at the track. First time happened about 15 minutes into a session at Buttonwillow in June. Air temp was approx 95F but all engine temps were good. I could hear the engine laboring/stuttering under full throttle in track mode/race setting. Eventually the car went into limp mode and that was the end of that track day.
Took it to the Chevy dealer since still under warranty and they found a few error codes (don't have them) and subsequently changed a temperature sensor and added coolant to a reportedly low supercharger coolant level. They also did a pressure check for leaks which was normal.
Took it back to the track last weekend and about 9 min into a session the problem occurred again. This time I quit after 1 1/2 laps after it started and called it a day. No error codes. Air temp 91. Engine temps all normal. Took it back to the dealer and they cannot replicate this on the street. Waiting for GM engineers to give some guidance.
I'm attaching a youtube video of the part of the session where this occurred. There is a lot of wind noise, but I've listed in the video description the times that you can hear the engine laboring.
Any help would be appreciated. Thanks!

https://youtu.be/HJb_1LQwnlE

I must say I've not seen anything like that before where the throttle is blipping up and down 100 or so rpms continually when throttling up. Just kinda of fluttering. Crazy.

maybe a bad fuel pump not able to keep up at full throttle?

How much fuel on board?

No PDR?

Possibility of air in charge air coolant?

It's a closed system, air bubbles in system will definitely pull timing.

Consider an external reservoir.

IAT advance due to lack of coolant in SC loop will not do that, it will apply a fixed value to cut back timing based on MAT, it isn't that (see table below from 2017 stock ZL1)

It sounds like throttle plate is being modulated. Would need to see log to see if timing or throttle is being modulated. An HP Tuners log would easily figure this out if the correct values were captured. It could be fuel related but it is way to consistent rate wise and I assume this is a near stock or stock vehicle?

What mode are you in for TC/SC?

It happens even when the tank is full

Car is stock except for roll cage/seat/6-point harness
I was in track mode in race setting
stupid question - I'm not familiar with HP Tuners log.

I have an AIM solo but I do not know how to really use it well for data. Might that help?

I don't have PDR
it happens even when the tank is full

Ok track/race mode makes answering some stuff easier, you don't have any TC/SC going to kick in, so it's not that.

If it was bad misfires you'd have a flashing CEL, so not that.

Using something like HP tuners a via OB2/CAN port on car could log what is going on. We would be able to see if TqMgtAdv or IATAdv was messing with spark, if immediate (spark - fast) timing or predicted (throttle body - slow) was being impacted by VT tables. I'd like to see what your throttle pedal is reading (via log), I can do what your video is doing if I allow my foot to bounce on throttle pedal.

What were the codes? You said it went into limp mode, did you see a message come up saying "reduced power mode"? What were coolant temps? Maybe you have a bad MAF sensor...

Does this have a stock tune?

Hmmm. I don’t think I have seen a problem like that before. First thought that comes to mind is heat somehow is affecting that throttle body from opening smoothly. But then I would think it would throw a code for a TPS or some code saying the pedal sensor isn’t corresponding right with the throttle body.

Come to think of it. I had an Iroc that did something similar intermittently. It would throw a code and once I put a multimeter on the ecm I found the ecm to be defective. What that car was doing was not allowing the timing to advance then it would advance then it would stop advancing causing a weird surge. I do not remember it being as pronounced as your problem. And again my problem threw a code for a timing issue. Yours should be setting some sort of trouble code.

I had a similar problem sort of... I went to Roebling Road in Savannah for a track weekend, and after the second session I was down to about a 1/4 tank of gas, so I bought some Sunoco gas at the track, and I put 108 leaded gas in there, because I dont have any cats or 02 sensors, so I didnt think the lead would affect either of those and I was thinking the extra octane would help with the hot day, 93 degrees. Next session's first couple of laps went well and then the car just started running sluggish, not quit into "limp mode", but every time I tried to give it throttle, it would fall on its face. Came in checked all connections, made sure nothing was unplugged and went back out and same thing after a couple laps. I guessed that the extra octane or maybe lead was doing something my car didnt like, so I finished the next session and burned off as much fuel as I could (down to 1/2 tank), and took the car off track and put 93 in it. It was the end of the day, so came back the next morning and problem was gone, have not had any issues since then, and that was about 1 year ago. So I presume either the track's gas pumps had some bad gas, or my car didnt like the leaded 108.

sounds like fuel delivery to me...someone needs to log fuel pressure and see if it reads low on either the low or high side. Problem is this issue is difficult to replicate on the street so you are at the mercy of code checking and diagnosis based on street pulls. Good luck... please update and report their findings.

Will answer as best I can:
1. The car went into reduced power mode when this happened in June after I kept running it. I took it to the dealer - this is the text from the repair invoice:
"Code P00EA intake air temperature sensor 3 circuit low voltage. Started tech assistance case - was advised to check circuit for intake air temp sensor 3 if all ok order intake air temp sensor. Found all wiring ok. ordered intake air temperature sensor 3. Found secondary cooling system for supercharger low causing possible high intake air temp sensor 3 readings. Filled and bled secondary cooling system and was advised by TAC to pressure test secondary cooling system. Pressure tested cooling system and found no external leaks"
2. This past weekend I pulled off the track once the problem recurred. I don't recall exact engine temps but all were in normal range - I had only been out on track for 9 minutes when this began. No error codes this time. No reduced power mode.
3. Stock tune.