Ever since Chev went to the electronically controlled 6 speed transmission in the Suburbans I noticed the downshifting is terrible. When you try to gradually speed up, while moving, it won't downshift without really stepping on it. It lags because of being in too high of a gear and won't shift smoothly.

Has anyone else noticed this and is there a fix either from GM or aftermarket? The dealer told me its the way they are but I have been driving these trucks for a long time and have been around cars my whole life to know better.

 

Welcome to the forum.

You can always use the manual mode.

 

I had the same issue with my 2011. I HATED the way it shifted. Always wanted to upshift through the gears to early and then hesitate and bog. Also wouldn't downshift as you said unless I gave it a lot of gas and then would downshift sometimes 2 gears.

I got a tune (AutoCal) from Black Bear Performance. It now drives and shifts perfectly. Shift points were raised so it doesn't bog and downshifts when needed. You can easily return it to stock with the AutoCal if you need to go to the dealer for warranty work. Some people will insist that the dealer can still tell but this is only true on Global A vehicles. I researched this issue EXTENSIVELY and haven't seen the first post where somebody had THEIR warranty denied if returned to stock. Also confirmed by Black Bear. If you go with another tuner or a handheld make sure it supports tuning the Transmission Control Module (TCM).

For more info go to http://blackbearperformance.com/ Click on contact us and then you can go to the forums they sponsor and search to get a TON of information.

 

Did you notice any mpg change?

 

About 1 mpg increase city and stayed the same highway.

 

Most aftermarket mods will improve shifting. They set the factory specs low so the trans shifts ASAP for optimal fuel economy. However, drive-ability is often compromised for gas mileage. Be careful with transmissions though...the cost for rebuilding these new 6-speed units are big bucks. Also, keep the trans temp less than 160 degree Fahrenheit for longevity. Good luck!!

 

Thanks HOE-N-IT. It's good to know I'm not the only one with the problem and there is a solution. Will check it out.

 

Just had my 2010 in for the same problem Chevy had to reprogram the TCM and the TCC. I've been driving it for two weeks now with no problems