I have an issue with the downshift of my 2011 Sierra 6L80E. If I am cruising from 40 to 45 MPH and do a quick Wide open accelleration the transmission downshifts to 1st gear hits the RPM shift point of 5900 and then shifts to second gear instead of just shifting into second gear. I posted the tune does anyone have an idea. It looks as if everything is setup properly I must be missing something. Thanks for the help.
2011 GMC Sierra 4X4 SLE Lysholm 2300 Supercharger 5" BDS Lift, 33X12.50X20 Nitto's and 20" Chrome Wheels.
I don't understand the problemOriginally Posted by hhoelle
Custom PCM Tuning in Hollywood Ca
Wait, are you saying it downshifts, hits the rev limiter, then goes to second?
Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.
PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.
Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
618/618 motor
906/862 spray
Caterpillar 50 Forklift- Duramax swap
I know exactly what you are describing. It has to do with shift speed overlapping, the factory tunes with a lot of these 6 speed autos aren't setup worth a crap. The shift speed tables need to be setup better.
It creates a really "violent" downshift feel, correct?
2017 Silverado LTZ
Yes it revs to almost the rev limiter and then hits second so hard it boils the rear tires as it is supercharged, I tried to remove all the overlaps the tune is attached if you want to take a look. In first gear it shifts out at 40 at 5925 rpm. While cruising at 45 if I do a wide open accerelation it will go all the way to 1st gear and tehn hit second instead of going to second gear.
2011 GMC Sierra 4X4 SLE Lysholm 2300 Supercharger 5" BDS Lift, 33X12.50X20 Nitto's and 20" Chrome Wheels.
Its speed and RPM based. Perhaps the rpm limit needs to be addressed.
I found with a sts-v I was working on that the cruise tables also needed to be addressed since I was running into an issue much like yours.
Have you tried adjusting the mph down to 30mph, for example, and see if it still does it?
that's how it is tuned from the factory, now add a Maggie and you think it is ripping your axles out so violent will it become!
first time i did a kick down to pass a truck on a country road I thought I wrecked the tranny.
stupid to downshift 3 to 4 gears, stay a split second in 1st or second and then shift up a gear. I eliminate that with playing with downshift speeds
Have you found the cure?
I looked over your tune and you shouldn't be having this problem. i did notice that in your speedometer table your current tire size is 32.00 and according to your signature your running 33's. i don't know if what you have in the tune is the actual or if you forgot to edit it for the correct size.
2008 Silverado 2500HD
357 rwhp 382 rwtrq tuned by me
MODs: CAI, cut out, cat delete.
(New Mods: Ported TB, pacesetter Long tubes, and off road Y= redynoing soon )
Any news?
I reduced the speed and it seemed to have fixed I had to go down to 33 mph upshift? The tires are listed as 33X12.50X20 but they actuallt measure 32" tall. I tested it against my GPS and it is withing 1 MPH so I thought close enough. Thanks for all the help. Now working on 3 bar setup as the stock MAP sensor only reads to 118kpa and i'm prodcusing 12 PSI boost which is higher than that.
2011 GMC Sierra 4X4 SLE Lysholm 2300 Supercharger 5" BDS Lift, 33X12.50X20 Nitto's and 20" Chrome Wheels.
Get a Zr1 sensor and a Katech wiring adapter. Plug and play. Enjoy.
Gray Ghost- The abomination. 2007 Chevrolet Silverado CCSB. 98mm turbo, nitrous, 428LSX, Rossler 80E with a brake. Finally finished. 23 psi, no numbers, Slow as hell.
PBM G8- Aluminum 364, twin Precision 67/66 turbos, 6L90 trans swap, CTS-V/Vaporworx fuel system, slowly making progress.
Dads 2011 CTS-V- Stock bottom end, stock heads, LS9 cam, pullies, ported blower, ported TB, D3 goodies, and lots of nitrous.
618/618 motor
906/862 spray
Caterpillar 50 Forklift- Duramax swap
True story
ZR1 Speed Sensor?
2011 GMC Sierra 4X4 SLE Lysholm 2300 Supercharger 5" BDS Lift, 33X12.50X20 Nitto's and 20" Chrome Wheels.
They'd moved on to the 3-bar MAP sensor discussion.
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