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2015 6 speed Transmission or TC issue?!

SlateGrey1500
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SlateGrey1500 New Member

SlateGrey1500

Posted
Posted

Hey there! I figured I would come to one of the best places for some advice and answers.

 

I recently bought a 2015 Silverado 1500 6 speed, it has a newly rebuilt transmission with new TC, like 5k miles on them.

 

The Issue:

Ever since driving it I notice a strange lack in acceleration or power in general.. like the transmission is just constantly slipping or something. I tried the power braking test and here is a video snippet of it:

 

https://streamable.com/mrtx4e
 

as you’ll see, while on the brakes and I floor the gas the truck barely builds to over 1k rpm... like the there absolutely no power to do anything.

 

I thought about going to a tuner and having them tune out the TCC engagement in 1st-4th gear but I’d like to know first this isn’t anything mechanical wrong. Any suggestions?

 

Thank you!!

KARNUT Senior Enthusiast

KARNUT

Posted
Posted
2 minutes ago, SlateGrey1500 said:

Hey there! I figured I would come to one of the best places for some advice and answers.

 

I recently bought a 2015 Silverado 1500 6 speed, it has a newly rebuilt transmission with new TC, like 5k miles on them.

 

The Issue:

Ever since driving it I notice a strange lack in acceleration or power in general.. like the transmission is just constantly slipping or something. I tried the power braking test and here is a video snippet of it:

 

https://streamable.com/mrtx4e
 

as you’ll see, while on the brakes and I floor the gas the truck barely builds to over 1k rpm... like the there absolutely no power to do anything.

 

I thought about going to a tuner and having them tune out the TCC engagement in 1st-4th gear but I’d like to know first this isn’t anything mechanical wrong. Any suggestions?

 

Thank you!!

If the transmission was slipping the RPMS would rise without pulling the truck, slipping. Try turning off traction control, brake torque a little then nail it. Your tires should spin and the light would blink. Most people would blame poor acceleration on power or lack of. But it’s the traction control kicking in.

SlateGrey1500 New Member

SlateGrey1500

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  • Author
Posted (edited)

I completely forgot to mention that too!

So when I nail it going down the road, the RPMs do shoot up like they should.. but the actual power to the ground just isn’t there like you would expect at WOT.

Edited by SlateGrey1500
pokismoki Senior Enthusiast

pokismoki

Posted
Posted (edited)

puting foot on brake while giving throttle just activates Torque managment, and you'll go no where..and pull timing..

 

try driving in M5 , this disables DoD v4 mode and removes the hesitation in D, when going wot, then try m4 mode combined with or without towhaul. 

 

Yes remove the TCC in 1-3rd for all around driving, remove tcc in 1-4th gives more power but at a cost of mpg losses. then delete the thermostat in trans.. have dealer or  tuner do a trans relearn and throttle clean

Edited by pokismoki
SlateGrey1500 New Member

SlateGrey1500

Posted
  • Author
Posted (edited)

@pokismoki

 

Thank you for the tips!!

 

I have installed a new MAF, cleaned the TB and did the throttle position relearn procedure for a safe measure. I will try those driving tests tonight or possibly tomorrow too!

 

I had no idea about the torque management killing power on a power brake like that, makes sense!

 

As for the thermostat delete, could you share a bit of info with me on what difference that makes? Thank you!

 

Edit:

Nevermind, I looked up a delete kit and watched the info video. Just ordered the kit!

Edited by SlateGrey1500
pokismoki Senior Enthusiast

pokismoki

Posted
Posted

there is a section in the HPtuner software that you can disable the power brake function so you can do standing burnouts or fast off the line launches without the tcm pulling timing but dont touch the TM until you know what your doing, i think  removing 15-20 percent is the limit, otherwise you damage the trans

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

Delete kits are free though, you can do it in your garage for free with no extra stuff.

 

You just flip the pill inside the thermostat and re-install it. Simple as that.

pokismoki Senior Enthusiast

pokismoki

Posted
Posted (edited)

i dont see how standing on the throttle and brake at the same time will diagnose a TCC it activates in motion and touching the brake pedal usually disables the lock up on some model trans..  usually tcc failure occurs when the o-ring on the snout  of the input shaft stops sealing fluid flow to the clutch in the tc.

 

the o-ring gets hard and fails due to the high temps inside a TC. thus why you want to run the trans as cool as possible

Edited by pokismoki

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