Jump to content

2015 6 speed Transmission or TC issue?!

SlateGrey1500
 Share

Recommended Posts

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

Posted
  • 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

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      So, do I go elbow-deep on this thing or list it for sale and play dumb? Seems to "runs good."   I'm about $1200 away from having: -a rebuilt injector ($300) -a new cat ($250) -a new cat back exhaust (OE style) ($300) -a new AC compressor ($200) -AC refrigerant charge ($150)   In theory, this should rectify the obvious detracting issues from its value and operability. Cold AC with a non-squeaking AC pulley both sounds and feels good. An exhaust that isn't cut/hacked in 17 different places and doesn't vibrate on a crossmember would make it sound and feel less janky. A working cat would help the stink, and will save the earth, but *if and only if* the fuel system is working properly, which would also address the intermittent "rich" CEL.   Heard a good one... CEL for "Rich condition" means you haven't spent enough money on the truck lately, and it's letting you know.   Rebuilding the injector would seem to be the most important part. Replacing the cat would be secondary. I don't think mine is plugged or overly restricted, but it might be a little restricted? I have no good way to tell other than seat of the pants feel. I hate the smell.   The current theory is I have a rich idle problem: A bad fuel pressure regulator, or a leaking injector(s) being the highest probabilities. I already replaced the FPR but that doesn't mean its replacement isn't also bad. It was a new part from Dorman, but the packaging looked like it had been sitting on a shelf for 20 years.   This is the (single) upstream O2 sensor shown at idle. I'm getting a lot of "rich" it seems. Sometimes it stays high like that and doesn't drop down. That makes me think it's processing injector leaks or a partially stuck open injector.     Other times it looks like this. Nice oscillations between rich and lean, which is what I think it should be. Under load and at speed, the oscillations are nice and tight and uniform looking, high and low.     Fuel trims suggest the PCM is compensating pretty hard at idle to pull fuel out. But it's not enough to trip a CEL. Something about slowing to a stop: brake vaccum booster, EGR, or the EVAP purge is delayed, or there's pooled fuel in the intake again that's draining into a cylinder is enough to set the CEL. Of course, in two days of driving, it hasn't set. I was hoping to actually look at the freeze-frame data when it sets. IAT is high because it's idling on an 83 degree day here.  
    • Another JR
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By Another JR · Posted

      Have considered installing a DC to DC charger in your camper to replace your isolator?  
    • newdude
      Gas fill door

      By newdude · Posted

      Common failure.  You need to replace the fuel door housing.   The painted cover transfers over to the new housing.  To remove the old one there is 4 spots where you poke the plastic to release it.  
    • newdude
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By newdude · Posted

      No such thing as regenerative braking on a pure ICE vehicle.     Regenerative braking is the re-capture of energy from electric motors and stores it in the battery pack.  So hybrids, PHEV and EVs have regenerative braking.     What you are seeing is the charging system changing modes is all.  Its likely entering charge mode for some sort of reason is all.  All of the charging modes will be listed below.   As for L10 vs D.  L10 turns off automatic grade braking.  L10 puts you in control of grade downshifts where in D it will automatically do it based on brake pedal position and other factors.  Otherwise L10 and D drive exactly the same aside from that one aspect.    Battery Sulfation Mode The BCM will enter this mode when the interpreted Generator output voltage is less than 13.2 V for 45 minutes. When this condition exists the BCM will enter Charge Mode for 2–3 minutes. The BCM will then determine which mode to enter depending on voltage requirements.   Charge Mode The BCM will enter Charge Mode when ever one of the following conditions are met:   Windshield wipers are ON for more than 3 s. Climate Control Voltage Boost Mode Request is true, as sensed by the HVAC control module via serial data. High speed cooling fan, rear defogger, and HVAC high speed blower operation can cause the BCM to enter the Charge Mode. The estimated battery temperature is less than 0°C (32°F). Battery State of Charge is less than 80%. Vehicle speed is greater than 145 km/h (90 mph) A current sensor malfunction exists. System voltage is determined to be below 12.56 V When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 V, depending on the battery state of charge and estimated battery temperature.   Fuel Economy Mode The BCM will enter Fuel Economy Mode when the estimated battery temperature is at least 0°C (32°F) but less than or equal to 80°C (176°F), the calculated battery current is less than 15 A and greater than −8 A, and the battery state-of-charge is greater than or equal to 80%. Its targeted generator output voltage is the open circuit voltage of the battery and can be between 12.5–13.1 V. When fuel economy mode is active, the generator is not charging, only maintaining open circuit battery voltage. The BCM will exit this mode and enter Charge Mode when any of the conditions described above are present.   Headlamp Mode The BCM will enter Headlamp Mode when ever the head lamps are ON (high or low beams). Voltage will be regulated between 13.9–14.5 V.   Start Up Mode When the engine is started the BCM sets a targeted generator output voltage of 14.5 V for 30 s.   Tow/Haul Mode (if applicable) Pressing the Tow/Haul Mode button located on the center stack, the vehicle system voltage is raised and the remote (non-vehicle) battery will be charged. Having the headlamps on will raise the system voltage and if the Tow/Haul button is applied it will not serve any purpose. The voltage is regulated between 13.9-14.5 V.      
    • jaszr2
      Active Grille Delete

      By jaszr2 · Posted

      Hello from Australia Just sharing that there is now a way to delete the active shutters entirely with just a plug in module. Opens up tons of room to light bars etc.

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...