Stalls only during burnout

[mommasGN]

Hoping for some input on a strange issue that has happened the last 3 or 4 times at the track.

The car runs beautiful everywhere and every time I drive it. Cruising, highway pulls everything. Going down the track, the engine doesn't miss a beat, it pulls hard and very consistent. The only issue i have is during my burnout. Every time, as soon as I start my burnout, the engine stalls. No matter what I am doing with the gas pedal. Sometimes just returns to idle, sometimes it completely shuts off. Always restarts right back. after once or twice, I am able to do my burnout, and make my pass with no issues.

No line lock, I do the burnout same as I always have, Foot on brake, as soon as tires start spinning, I let off of the brake and hold the gas to the floor while rolling out of the water.

I will say, My KR goes crazy during the burnout (but it always has). No KR on my pass though.

any thoughts?

 

[GNVYUS 1]

Just to give you some ideas to check through...

Shift knock too?
Motor mounts, poly or stock rubber (age)?
Noisey valvetrain?

Knock will suck away timing and it sounds like it's happening right away during hard pedal hammers so the above might be a way to quiet or down during the quick changes in rpm.

 

[Sweet6]

My guess is it is loading up on fuel during the burnout and when you let off the gas and it stalls out when the throttle closes.

The KR could be false knock from exhaust etc moving around

 

[mommasGN]

Just to give you some ideas to check through...

Shift knock too?
Motor mounts, poly or stock rubber (age)?
Noisey valvetrain?

Knock will suck away timing and it sounds like it's happening right away during hard pedal hammers so the above might be a way to quiet or down during the quick changes in rpm.

Hr engine mounts

For a roller, i feel like the valvetrain is fairly quiet.

Very rarely do i get a blip of KR on the shift

I was kind of wondering if its pulling so much timing, causing it to lose power

 

[mommasGN]

My guess is it is loading up on fuel during the burnout and when you let off the gas and it stalls out when the throttle closes.

The KR could be false knock from exhaust etc moving around

It happens while still holding the throttle open.

 

[Sweet6]

It happens while still holding the throttle open.

Have you logged the AFR when you are doing all of this? That will be the easiest way to tell.

But as the throttle is closing from where it was during the burnout less air is getting into the engine. Then it cant burn all of the fuel off and it stalls.

 

[TurboBob]

what chip or ecu?

got a logfile of it happening?

 

[GNVYUS 1]

From one frustrated ghost chaser to another, time to follow TurboBob, log, pray the ghost appears and someone can call the Ghostbusters for you. Good luck, I'll follow this.

 

[Mr.Spool]

My guess is it is loading up on fuel during the burnout and when you let off the gas and it stalls out when the throttle closes.

The KR could be false knock from exhaust etc moving around

Sounds like it's loading up too me too

 

[THensley]

with KR it will pull lots of timing that can't burn the fuel at WFO
Need to find your false KR, and hopeful it is false.

 

[TIMINATOR]

Borrow another set of rear tires and see if that changes anything. If it's false knock retard, something should change for better or worse. Tires may be chattering and transmitting the vibration to the exhaust or mounts. Changing the tire pressure up or down may change it also, but not as much.
This could also be a burnout style issue, as in not lifting before the tires hook and the subsequent "chirp" at the end of the burnout. This causes a sudden shock load to be transmitted up the drive train,
causing metal to metal contact somewhere that the continous engine torque during a run couldn't.
Just a few things to look at....
TIMINATOR

 

[TurboBob]

If it was happening on drop-throttle I was thinking MAF backflow causing overfueling. Might be compressor surge tho.

But it sounds like he's saying that it 'stalls' even when the throttle is held open. So I'm starting to think that an ecu safety mode may be triggering, or perhaps the ignition is losing sync.

Bob

 

[Mr.Spool]

Hoping for some input on a strange issue that has happened the last 3 or 4 times at the track.

The car runs beautiful everywhere and every time I drive it. Cruising, highway pulls everything. Going down the track, the engine doesn't miss a beat, it pulls hard and very consistent. The only issue i have is during my burnout. Every time, as soon as I start my burnout, the engine stalls. No matter what I am doing with the gas pedal. Sometimes just returns to idle, sometimes it completely shuts off. Always restarts right back. after once or twice, I am able to do my burnout, and make my pass with no issues.

No line lock, I do the burnout same as I always have, Foot on brake, as soon as tires start spinning, I let off of the brake and hold the gas to the floor while rolling out of the water.

I will say, My KR goes crazy during the burnout (but it always has). No KR on my pass though.

any thoughts?

What computer are you on?

 

[mommasGN]

Turbotweak 5.7 chip

i have many logs. I've stared at them many hours to see if its something obvious losing power or signal.

I usually start recording before i even get to the burnout box so i can focus. I'll dig some up and post them.

 

[mommasGN]

If it was happening on drop-throttle I was thinking MAF backflow causing overfueling. Might be compressor surge tho.

But it sounds like he's saying that it 'stalls' even when the throttle is held open. So I'm starting to think that an ecu safety mode may be triggering, or perhaps the ignition is losing sync.

Bob

Yes, it does it while the throttle is still held open.

 

[Chuck Leeper]

What are batt volts when this happens?
Where is the battery?

 

[mommasGN]

i have a volt booster so i am at 15.7 .That was a thought i had.

battery in factory location
Once i get to my laptop, ill share a log.

 

[mommasGN]

sorry for the delay. between work and kids sports......


heres a log of a run at the track. from frame 2050-3000 was the burnout attempt. you can see it took several attempts and i was finally able to do a full burnout, then make my pass with no issues.

 

[TurboBob]

It looks to me like you are too heavy on the throttle during the burnout kicking the chip into full boost (full fuel) mode. Its the nature of stock-MAF style chips.

Contact Eric at TurboTweak, he likely can set the threshold higher or give you some hints on burnout technique with that 5.7 chip.

Bob

 

[SCOOBY DOO]

PL shows your MAF maxed at burnout...prolly why it's stalling when lifting. I'm surprised you haven't windowed the block. Might wanna think of changing your burnout technique.