[seanblurr]

Posting this here too, apparent electrical issue on ZL1 1LE caused eLSD malfunction and "limp mode" today while on track. This is new to me, haven't read anything on the internet of people with similar symptoms. Full summary and TLDR bellow.

Car has 6k miles and is trailered to and from the track, not street driven. FYI.

TLDR: Car would do one wheel burnouts, morphed into the car sputtering through the RPM range (not actually sputtering, but it was hesitating and gaining RPM's slowly before holding steady at around 5,500 and not going anywhere). Felt noticeable down on power, car would fall flat on its face during higher RPM's. No CEL's, No reduced power warning. Thoughts?

Full Summary: I ran the car two weeks ago at Laguna Seca without issue, today was day 1 of 2 at Sonoma. I ran for the first time a 315/30/18 tire on all four corners (using 18x11/12 wheels, not true square) in an effort to find a solid tire for this car that last a bit longer.

Within the first lap, the car would only give full power with zero steering angle. If I was mid-turn or exiting, it would just hold steady until I was pointed straight, then would come on power. I thought I had mistakingly exited out of PTM:Race, it was as if I had full assist on in wet/ice mode. Turned TC/ST fully off and realized why the TC was engaging so much, the eLSD appeared to not be working. Anytime the inside wheel was unloaded I would get massive wheel spin. I tried to push it exiting turn 11 just to see what would happen and I got a huge smoking one wheel burn out down the straight. That's not right.

So what happened? I used an OD2 reader to clear an exhaust code (02 sensors, probably from my cat-back) prior to going out. I then plugged my AIM SOLO2 DL into the OBD port to pull data and went out for my first session.

1. Did my SOLO DL trip out the electrical system somehow and cause the eLSD issues? (Ive heard of this)

2. Did the change to a square 315/30/18 put the cars calibrations out of its % variance and trip out the e-diff?

So moving on to the remaining sessions.

Second Session: First step was to pull the battery cable and let it sit for 10 minutes. Continued to use the SOLO DL and still had the same problems. Absolutely no power with any sort of steering angle, power came on decently strong when pointed straight. No Change.

Third session: Reset battery once again, and this time I ran without my SOLO DL. NO change. Ok, so maybe it is not related to the OBD port and it has to do with the wheels.

Fourth session: I reset the battery and put on my stock wheels and tires. Power was able to be applied during corners now and I didn't appear to have any one-wheel burnouts anymore, except, well, I also didn't seem to have any power. Exiting onto the front straight in second gear it would slowly climb through the RPM's until 3rd and 4th. It would climb the RPM's but a hair more slowly, hesitation was more apparent near redline in 3rd. A few turns later exiting 6 in 3rd gear (generally exited 3rd at 85, quickly hit limiter and on to 4th). Well I was flat, exiting around 75 and the car was taking forever to climb the RPM's, noticeable enough, it hesitated and sputtered around 5500 and would just ride there without reaching 6500. Upon upshift to 4th, the car would gain some power back and pull. This high RPM hesitation continued for the next few laps. Upshifting and bringing the RPM's down appeared to give some power back.

I pitted, checked temps, nothing in the red. No CEL's or warnings. I then floored it in 1st leaving the box and the car wouldn't even spin the tires. The car also just sounded.. "flat".

The car was driveable, and I could have stayed out there had I wanted to, but it was definitely having power issues. I don't quite know if this is what limp mode feels like or what. The only thing I could equate it to is the feeling when you are low on fuel and the car slightly hesitates as the fuel sloshes around.

The 18's have TPMS that was never reset, though they were set to this car the last time they were on the car and were actively showing temps. Stock wheels and tires have no TPMS, warning light had not activated yet during the fourth sessions.
Could a bad, slipping clutch be noticed by the ECM, causing the computer to pull power so I don't burn out the clutch?

I am at a loss. With no codes and no way to replicate on the street, I have a hard time believing any dealer will know what to do.

Anyone?

[Osbornsm]

Well there's two common wiring harnesses on the Camaro that get chewed up.


There is the harness in the Left-rear wheel well.
AND
There's a harness next to the right side of the engine bay, which likes to melt without headers.


Thoughts?

[TrackClub]

There is also another harness that can rub the ac belt i think. Some early 1LEs had this issue.
Hope you find the root cause of it. Electronics can be a huge pita!

[TrackClub]

Another thought: have ya tried running it with all nannies off? If the problem went away then it could be TC wheel sensors. If not, then possibly an electrical issue somewhere, or electronic part of the ediff is gone (which sits above the main "pumpkin"). Just a thought, as i am not mechanically inclined...

[gotroost]

Could it be one of these service updates? Still waiting on one of these to be done on mine but I haven't exactly been hounding the dealer.

[seanblurr]

Does anyone know what these cars are programmed to allow for a percent variance between the front and rear wheel diameters?

I was talking to some Porsche guys at the track who said if they don't have somewhere between a 2-3% difference in diameters (height). the car's electronics go haywire.

Someone also claimed to know GM's require at least a 2% difference in diameters.

I would believe this, but I know there are members on here who have run square tires successfully. Though, I don't know if any of them are ZLE's.

Thoughts?

[Provoste]

Originally Posted by seanblurr

Does anyone know what these cars are programmed to allow for a percent variance between the front and rear wheel diameters?

I was talking to some Porsche guys at the track who said if they don't have somewhere between a 2-3% difference in diameters (height). the car's electronics go haywire.

Someone also claimed to know GM's require at least a 2% difference in diameters.

I would believe this, but I know there are members on here who have run square tires successfully. Though, I don't know if any of them are ZLE's.

Thoughts?

Yeah, Porsche’s sensitivity to F/R OD % is more related to AWD 911’s drivetrain and diffs. Not sure GM would go to the trouble of doing unique OD tune for the ZLE, considering all SS1LE/ZL1/ZLE all have a 20mm tire difference difference F/R. Have also seen at least one ZLE run square 305 with no issue. Obviously lots of SS 1LE guys (you previously I know) running square fitment. Sorry no pointers on my end.

[rotis]

315 Square is fine. What are your full list of mods? Any chance your battery has low voltage? I think that happened to Jr at nats, and it resulted in the diff staying open.

[seanblurr]

Car is entirely stock. I havent checked the battery voltage.

[RUQWIKR]

For ABS, TCS, etc, the % issue is front to rear difference. Let us know what you find out. Which 315/30/18 did you try? (Yokaham A052? is on my to-try list)

[TrackClub]

I'd defo check those 2 recalls posted earlier as a start.

[seanblurr]

I tried the Nankang AR-1's and they were GREAT.

So riddle me this fella's.

I just drove around for some time with stock wheels and tires and after a while, I really did not notice the car acting funny at all. I attempted a few pulls entering the freeway as safely as possible and it appeared to pull strong to redline.

The only change between that 4th session of the day (with stock wheels) and my drive just now is the car finally registered it had no TPMS. Prior to that, it still thought a wheel was on the car that it wasn't.

So, the issue was either related to 1. the wheel size, 2. TPMS plays more of a factor than we thought and it was throwing the car entirely out of whack, or 3. it takes a bit of hard use for the issue to show.

[Provoste]

Originally Posted by seanblurr

I tried the Nankang AR-1's and they were GREAT.

So riddle me this fella's.

I just drove around for some time with stock wheels and tires and after a while, I really did not notice the car acting funny at all. I attempted a few pulls entering the freeway as safely as possible and it appeared to pull strong to redline.

The only change between that 4th session of the day (with stock wheels) and my drive just now is the car finally registered it had no TPMS. Prior to that, it still thought a wheel was on the car that it wasn't.

So, the issue was either related to 1. the wheel size, 2. TPMS plays more of a factor than we thought and it was throwing the car entirely out of whack, or 3. it takes a bit of hard use for the issue to show.

Not super clear on your conclusion? ... I’ve run OEM 3R’s with no TPMS (TPMS light on) with zero issue, PTM Race/Full off tc/stability. You’re thinking it is that interim period where the car hasn’t established the lack of TPMS sensors where the car goes crazy? I’ve driven that first session without TPMS (where 1 lap in the TPMS warning comes on) previously without issue... no power cut. You thinking the OD change combined with no TPMS makes the car wig out?

[RUQWIKR]

I thought if the car "sees" no TPM sensors, e-LSD, TCS, PTM, Stability, etc. still work {like Provoste says above}, but anything between 1 and 3 sensors still recognized throws fits [if my memory is correct].