Stabilitrack thrashing?

[SSSoon]

Would appreciate any thoughts y'all have on this one.

It started when I was at Summit Point, but happens consistently every time. Bring the car up to speed, 3rd gear, 5k rpm, mash the throttle and I get a loud rapidly repeating banging noise, the three yellow Stabilitrack-related lights come on, the Service Stabilitrack message pops up, and doesn't disappear for 30-60 seconds afterwards. While the banging is going on, my boost gauge also thrashes around and I have no ability to accelerate. Stops the second I get off the gas. Does not happen under gentle acceleration, only under hard acceleration, and only at 5k+ RPM as far as I can tell. When I take the car to my GM mechanic, he can find no codes that indicate any problems.

I did some engine datalogging and sent it do Ted Jannetty (thanks Ted!), who concludes that the engine is pulling timing to protect the engine because it thinks whatever it banging around is the engine knocking (but it is probably false knock).

At first I thought it was caused by a broken sway bar bolt (one bracket that holds the sway to the car was loose) but after replacing it with a hardened bolt, same problem.

I know some of you will suggest: Turn Stabilitrack off and see if it still happens. I might yet do that, but my first instinct is NOT to turn it off when the car is clearly having some problems and when reproducing the problem requires high speeds and WOT. I do not want to be that guy who ends up in the ditch because he disabled the safety system that was preventing the malfunction from putting his car sideways.

I work with a great GM tech who is going to ride along with me on Tuesday afternoon with his scanner hooked up to the OBD port to see if he can figure out what the hell is happening in real time. But between now and then I am just at a complete loss to figure out what's going on. Maybe a failing wheel speed sensor? I don't know what the symptoms would be of that...

Thanks guys

Pete

[Synner]

I'm 99% sure when you find and fix the cause of the banging the stabilitrack issue will disappear with it. Those lights like to go on for unrelated issues at times just because the ECU is flipping out and doesn't know how to respond.

[Synner]

Maybe check for a broken motor mount...?

[BruHop]

I know I had two problems on two different occasions running AutoX with the controls on. I would start the car for the next run and the system said I have a power steering problem, ABS light was on. It said get service. I had to cycle on and off 10 times for it to clear. Turned off the traction and stabilitrac, ran in competitive mode and NO issues. What someone told me, is the computer doesn't like the hard accelerations (like you are trying to break the tires loose) when the system is on. I don't know about your "hard banging" sounds though. But I do think you should try it with it off. I also get your reasoning for not wanting to do it. Try a straight line.

[SSSoon]

Originally Posted by Synner

I'm 99% sure when you find and fix the cause of the banging the stabilitrack issue will disappear with it. Those lights like to go on for unrelated issues at times just because the ECU is flipping out and doesn't know how to respond.

Thanks Synner. Definitely possible. The reason I think Stabilitrack is involved is because of the rapid banging - almost like ABS is kicking in while accelerating.

Originally Posted by Synner

Maybe check for a broken motor mount...?

Good idea - will have a look when I get it up on the hoist.

Originally Posted by BruHop

I know I had two problems on two different occasions running AutoX with the controls on. I would start the car for the next run and the system said I have a power steering problem, ABS light was on. It said get service. I had to cycle on and off 10 times for it to clear. Turned off the traction and stabilitrac, ran in competitive mode and NO issues. What someone told me, is the computer doesn't like the hard accelerations (like you are trying to break the tires loose) when the system is on. I don't know about your "hard banging" sounds though. But I do think you should try it with it off. I also get your reasoning for not wanting to do it. Try a straight line.

The reason I think it is caused by something broken or failing is that I have done many, many road course events and AutoX events and it has never done this before. In fact, it first started suddenly after a bunch of laps at Summit Point that had zero problems even under hard acceleration. Now it does it consistently...

On an unrelated issue, my "Check Stabilitrack" light has been coming on consistently when I am at the track (and never when I am away from the track), but it is likely because of RFI. Pulling the codes showed a range of communication errors. I had thought that it was because of my OBD dongle, but driving around at home for weeks with the OBD dongle plugged in did not reproduce problem. Then once when I was at VIR I parked the car the night before, all fine. When I turned the car on in the morning and before I had even put it in gear, the Check Stabilitrack light came on - so clearly not because of anything I had done. I think there are so many custom electronics OBD devices in a crowded paddock area that other people's devices are creating RFI. There's a TSB out for OBD dongle devices causing RFI and affecting people's communication. Funny that it can be other people's devices because it sure wasn't mine that one time.

[BruHop]

Originally Posted by SSSoon

The reason I think it is caused by something broken or failing is that I have done many, many road course events and AutoX events and it has never done this before. In fact, it first started suddenly after a bunch of laps at Summit Point that had zero problems even under hard acceleration. Now it does it consistently...

On an unrelated issue, my "Check Stabilitrack" light has been coming on consistently when I am at the track (and never when I am away from the track), but it is likely because of RFI. Pulling the codes showed a range of communication errors. I had thought that it was because of my OBD dongle, but driving around at home for weeks with the OBD dongle plugged in did not reproduce problem. Then once when I was at VIR I parked the car the night before, all fine. When I turned the car on in the morning and before I had even put it in gear, the Check Stabilitrack light came on - so clearly not because of anything I had done. I think there are so many custom electronics OBD devices in a crowded paddock area that other people's devices are creating RFI. There's a TSB out for OBD dongle devices causing RFI and affecting people's communication. Funny that it can be other people's devices because it sure wasn't mine that one time.

OK, I believe you are on the right track with something being broken. But, I have to ask, I know you have concerns, but with all the road course and AutoX experience and the mods on the car, Why do you still run with the nannies on? You have the experience, you must be making the system overwork. Just go to competitive mode every time you are at the track.

[SSSoon]

Originally Posted by BruHop

OK, I believe you are on the right track with something being broken. But, I have to ask, I know you have concerns, but with all the road course and AutoX experience and the mods on the car, Why do you still run with the nannies on? You have the experience, you must be making the system overwork. Just go to competitive mode every time you are at the track.

I have never found them to be particularly intrusive, so don't see the harm in keeping them on in the background.

[BruHop]

Maybe not intrusive, but the computer on my car doesn't like it you are driving it competitive. it freaks out when I spin the wheels with it on.

[SSSoon]

Just in case anyone was interested in what the Camaro fuel tank looks like.

Putting in ZL1 fuel pump and ADM controller before doing any more testing as the datalog showed significantly reduced fuel pressure on hard runs.

[SSSoon]

Fuel pump in, tech in passenger seat with OBD device hooked up to watch and diagnose in real time, on highway, 55~mph, third gear.

Me: Okay, now listen to what happens when I floor it

(floors it)

Tech: I don't hear anything?

Me: wait for it

L99 (hits 5000 rpm, boost gauge goes wild, lights flash on dash): BANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBA NG
BANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBANGBA NG
BANGBANGBANGBANGBANGBANGBANG

Me: &^%$%@^

Tech: Wow, that's a lot of misfires!

L99 (all the way back to shop, no matter what speed): BANGBANGBANGBANGBANGBANG (etc)

RIP L99

The story arc has reached its lowest point, but there's more coming... but that's for another thread...

[130R]

Man, really sorry to hear. So did it grenade? If not, kinda sounds like (from your original post, and in hindsight) it might have been a bearing going.

Keep us posted on what you discover, and good luck!

[SSSoon]

Originally Posted by 130R

Man, really sorry to hear. So did it grenade? If not, kinda sounds like (from your original post, and in hindsight) it might have been a bearing going.

Keep us posted on what you discover, and good luck!

Don't know exactly what failed, but we will know this week.

Build thread started: http://www.camaro5.com/forums/showthread.php?t=375392