Supercharged 2012 kicked into neutral under heavy acceleration??

timmay20twelve · June 12, 2012

Guys,

I have a roots style supercharger on my 2012 Z71 5.3L and when I was driving home from work today, under moderate/heavy acceleration, my truck kicked into neutral unexpectadly......... after 2 sec. it bumped back into gear and has since seemed to drive fine..... Any input????

ruggedlife · June 13, 2012

doubt it was neutral.. it was probably the stabilitrac bs, tires were either spinning or they thought it was, it seems to just lose all throttle and then re-gain it. everytime i get in my truck i turn it off i do not like it. press and hold the button down for 5-10 seconds, the dash will eventually say stabilitrac off and have a light on. mine has done it ever since i re-geared my truck with all the other stuff on it. no idea why but i know it drives a lot better without the stabilitrac on

timmay20twelve · June 13, 2012

I always turn mine off too...... The tire thing is possible as the factory tires done really scream for the first couple seconds. I am just a little uneasy with the way it felt. I assume because the truck can tow a big ole trailer the trans is pretty strong (I think GM has rated it 700 lbs/ft). I am just a weeee bit scared ;)

timmay20twelve · June 13, 2012

Another reason I know it wasn't the stabilatrac is because the RPM's shot up and hit the chip......

ruggedlife · June 13, 2012

hmm thats true...weird i'd monitor your trans temps closer. if all else fails you can send your supercharger to me and i'll see if it does it to my truck

nbscanuck · June 13, 2012

if you hit the rev limiter, its there to prevent you from over revving. that's your "neutral" feeling you encountered

nickvrebel · June 13, 2012

You need to discuss this with whoever tuned your truck.

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timmay20twelve · June 13, 2012

nbscancuck - something caused it to free rev up to the chip...... I really can only describe it as going into neutral because it didn't feel like it was spining the tires. I felt if fall on its face and rev up, I look down and the tac was about maxed out, then as it was slowly falling it bumped back into gear and came down to about 1500 rpms. It did drive fine to work this morning and I jumped on it pretty hard too.

Nick - he has been emailed.

Jennabear · June 13, 2012

Have you had belt slip issues?

nbscanuck · June 13, 2012

Sorry my bad. Though it was your foot that was causing it to rev to limit. It did it on its own?

timmay20twelve · June 14, 2012

Jenna - I don't think it is belt slip issues....... I believe the only thing I would immediately see during belt slip is a loss of boost correct? I am really not sure, it just what I think. The engine would still have the drive line putting load on it. I did a couple miles before have it in the maunal shift mode but had since put in back in drive, made a stop and driven a mile or so. The actual gear selector never popped into neutral, just seemed to do it on its own for a sec or two. After talking with the engineers at work they said it was really weird and to probably just chalk it up to a fluke.......... Not the answer I wanted to hear but it seems like that was the case. I let her eat from a dead stop last night until I hit the speed limiter so..... I am truely purplexed. I guess time will tell.....

nbs - no woories man... Ya, something alowed it to free rev straight up to the rev limiter..... and fast!

timmay20twelve · June 22, 2012

Quick update...... All is well, going to cruise Woodward Ave tonight to show off the new graphics so I am sure it will get tested a few more times

tazerbro · June 28, 2012

Sounds like what happens to my truck when the torque management kicks in. All of a sudden the truck just falls flat on its face for a few seconds like I completely took my foot from the pedal. I see that as a safety issue. If you want the truck to GO and all it does is NOT GO...I consider that a problem.

music · June 28, 2012

I assume because the truck can tow a big ole trailer the trans is pretty strong (I think GM has rated it 700 lbs/ft).

The 6L80 is rated at 440 ft/lb (470 hp) @ the input shaft.

Doug_Scott · June 28, 2012

Jenna - I don't think it is belt slip issues....... I believe the only thing I would immediately see during belt slip is a loss of boost correct? I am really not sure, it just what I think. The engine would still have the drive line putting load on it. I did a couple miles before have it in the maunal shift mode but had since put in back in drive, made a stop and driven a mile or so. The actual gear selector never popped into neutral, just seemed to do it on its own for a sec or two. After talking with the engineers at work they said it was really weird and to probably just chalk it up to a fluke.......... Not the answer I wanted to hear but it seems like that was the case. I let her eat from a dead stop last night until I hit the speed limiter so..... I am truely purplexed. I guess time will tell.....

nbs - no woories man... Ya, something alowed it to free rev straight up to the rev limiter..... and fast!

Not sure I would chalk it up to a fluke. You may want to take a close look at the shifter adjustment. Years ago, the first day I started a new job at a Chrysler dealer, I got a warranty (actually come-back of another mechanic) trans repair on a Cordoba. While driving the car in I noticed that you had to pull hard on the floor shifter to get it engage drive. After doing the diagnostic tests that I was taught, it showed that pressures were low when in drive. Pressures were ok if I pulled on the shifter hard. Rebuilt the transmission to correct the burnt clutches and plates, adjusted the shifter, and let the car go. Found out from couple of mechanics at that dealership that the transmission was rebuilt 3 times before I got the come-back (guess they figured new guy won't bitch about fixing someone else's comeback), the original mechanic never did adjust the shifter.

If I were you, I would be checking and rechecking shifter adjustment. When you get on gas, the engine will twist against the mounts, if the shifter is borderline adjusted, it may just move enough to reduce pressures and and start slipping. Once the engine returns to normal position, the shifter gets closer to being fulling engaged. Something easy to check and repair if need be.

When it happened, did you happen to take note of the speedo? Was it showing the proper speed, or did it follow the rpms? If it followed the rpms, that would point you in the lack of traction direction. If you get on it hard, you are pushed back in the seat, and if the tires suddenly lose traction, you may get the feeling of being thrown forward as you lose the g forces suddenly.

Forgot to ask, what supercharger kit did you go with? Any install experiences you can share? Or did I miss the install post? I am seriously looking into this for my 2010 ECSB 4.8. I know it will be a roots type for me, just looking for experiences with install.