Jump to content
  • Sign up for FREE! Become a GM-Trucks.com Member Today!

    In 20 seconds you can become part of the worlds largest and oldest community discussing General Motors, Chevrolet and GMC branded pickups, crossovers, and SUVs. From buying research to owner support, join 1.5 MILLION GM Truck Enthusiasts every month who use GM-Trucks.com as a daily part of their ownership experience. 

Sign in to follow this  
DENALIHD66

8 Speed Trans Fixed? Am I onto something?

Recommended Posts

Posted (edited)

I have a 2015 with 8 speed and have had issues with it since the first month.  Very hard shifts 1-2 and 2-3 on cold starts (100%) of the time.  Also weird shifts on in-between gears, etc.  Basically everything that everyone else is complaining about with these.  

 

I got a blackbear tune done, and that helped minimize some of the annoyances with it.  One thing remained, the clunky shifts 1-2 and 2-3 on 100% of cold starts.

 

Yesterday I took apart the cold air intake, MAF, and throttle body.  Cleaned everything all up.  (First TB cleaning and it wasn't that bad after 51k miles).  Put everything back together.  It took a couple of cranks to get it to start, the first 2 cranks it stalled out.  3rd attempt it fired up and idled fine.  When coasting down my hill, I noticed the 1-2 shift was smooth and quick as silk.  The whole drive thereafter the shifting was absolutely perfect, and this was right after it sat (cold start mind you).  

 

One odd thing was that my cruise control wasn't working.  After getting to my destination, I shut engine off, waited a minute, cranked it back up.  Same thing kept happening, it would fire up then stall out within seconds.  I had to rev the engine in order for it to stay on.  Long story short, I figured out I mounted the MAF sensor in backwards by accident, so I flipped it around.  Truck fired up fine, but then the harsh 1-2 shifts etc returned.

 

 

I am wondering if I am onto something as far as the MAF and how it shifts during a cold start?  I believe there is also a TSB notice about excessive casting when the MAF was manufactured, and it relates to hard shifts after a cold start.  I'm currently searching online to find it, with no luck so far.  Was wondering if anyone would chime in and let me know what they think.  Would replacing the MAF be beneficial?  I cleaned the crap out of it when I had everything apart.

 

 

Edit: Found a thread started with no responses.  Not sure exactly what part to inspect?  Is this the OEM air intake or does it refer to the MAF that carries over to be used in a Cold air intake?  PIP5446

 

 

Edited by DENALIHD66

Share this post


Link to post
Share on other sites
15 hours ago, silveradosid said:

oem intake

Care to elaborate?  Truck also had the same transmission problems with the oem intake.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  



×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.