issue Transmissions Issues/Problems

KARNUT · April 17, 2014

What Ive read and feel when I drive my truck is for better gas mileage they are back driving the engine. Its seems that the fuel shuts off to the engine, the converter stays lock up to keep the engine spinning when you let off the gas. Feels like your driving a stick, the converter lets go the engine gets fuel. I notice the engine stays in V4 all the way down too. Its a different feel for sure but worth it for better fuel mileage. I notice a different feel when I put the truck in M and click to 6,I do that so when I get under 60 I drop down to 5 to keep it out of V4.

scott19677 · April 20, 2014

What Ive read and feel when I drive my truck is for better gas mileage they are back driving the engine. Its seems that the fuel shuts off to the engine, the converter stays lock up to keep the engine spinning when you let off the gas. Feels like your driving a stick, the converter lets go the engine gets fuel. I notice the engine stays in V4 all the way down too. Its a different feel for sure but worth it for better fuel mileage. I notice a different feel when I put the truck in M and click to 6,I do that so when I get under 60 I drop down to 5 to keep it out of V4.

Yes. I use manual mode as well to stay away from v4 when under 50 mph. It is the only way I can tolerate this turd.

OUSux · May 1, 2014

Well I took mine in for the random horrid clunk shift and they said, "it's a six speed, it's always shifting." well no **** Sherlock! They had it a day, couldn't replicate so I picked it up and at the first stop light I went to take my foot off to coast and it hesitated like it didn't know what to do and wham it slammed into gear, doing exactly what I took it in for..... Ugh

KARNUT · May 1, 2014

It seems these trucks are so intolerant any little change causes them to get all funky. Looks like you put bigger tires and did a lift? I get a clunk sometimes feels like gear hunting to me.

OUSux · May 3, 2014

It seems these trucks are so intolerant any little change causes them to get all funky. Looks like you put bigger tires and did a lift? I get a clunk sometimes feels like gear hunting to me.

Bigger tires, no lift though

55Cameo · May 8, 2014

Put me in the category of "clunk city". Can't say I get the superhard shifts you guys talk about, but when you back off in 2nd and 3rd, then re-accelerate, sometimes there is a pretty hard clunk, almost like a driveline slap. (In the old days you would think you had a bad u-joint).

Should I keep hoping it "learns" how to drive with me? 2100 miles.

selmahotrod · May 12, 2014

My trans acts up too, it just shift into high way to quickly and leaves you wondering when will speed build!

cory2014 · May 14, 2014

well I am glad I'm not the only one but am sad everybody is having the same problem. I've owned 8or 9 vehicles in my life. This is the only one that exhibits signs of something in the transmission to rear end area is wrong, and apparently that's just the way its supposed to feel. I am a body man by profession not a mechanic, but have had plenty of experience in transmissions, clutches u joints rear ends, you name it I've been in it. This is the first brand new vehicle I have ever owned. My 1998 k1500 blew the number three cylinder wasn't worth fixing it so I decided I deserve a brand new truck. I went to the dealership and said I want my truck just in a 2014 model year. That's what I wanted and I got it. I did not feel the need to test drive it. I am a Chevy man and figured that a truck with 3 miles on it would not have any issues. After I drove the truck for 122 miles I immediately regretted my 40000$ mistake. I paid for a new truck and want it to feel that way. The drivetrain feels clumsy and worn out. Ill never buy another new gm product. I didn't even look at any other truck based on how great of a truck my k1500 was. It was a work horse with no problems until the cylinder fail. But trust me the truck was used and used hard for 15plus years with nothing but oil changes. The only saving grace here is the 5year 100000mile powertrain warranty. The nail in the coffin for me was the undercarriage. Anybody who has a 2014 Silverado go outside get on your back and feast your eyes on the rust. This pissed me off beyond belief. The dealership offered me a new truck in replacement which was great of them, except every truck on the lot looked 5years older than it was underneath. My truck had 100 dry miles on it when I noticed it. The service tech said he hadn't seen anything like it. I have, I am a body man I know rust. It looks like all the pieces used to build the undercarriage of the truck were submerged in water for 6weeks before being pulled out and had a little paint dusted on them..And you would expect to see rust on the underside of a truck. When its years older not when my truck was built Jan 14. Three months old. Every truck on the lot had painted suspension components and rear ends rusting so bad the paint was popping. Lay under your trucks and see for your selves. Even the truck on the show room floor had the same issue. Makes me sick to see the direction vehicles are going these days. You pay 40000 and you get a clumsy rusted reminder of what gm used to be. I should note the service manager took pictures and documented my complaint i am still awaiting a word from gm as I was told he was sending some sort of writeup to gm. I'm smart enough to know ill get the run around.

55Cameo · May 14, 2014

I have friends who name their vehicles. I thought it would be nice to assign a moniker to my brand new GMC, but struggled with what that name should be.

After 3000 miles, It couldn't be more obvious........"Captain Clunk"

Starting down the road with dealer discussions......aaaargh.......

Charliepotato · May 15, 2014

I have 2,200 miles and twice now after going down a fairly long hill at about 25 mph I take my foot off the brake at the bottom and press the gas pedal only to find the engine rpm's go up but truck acts like its in neutral. Same hill both times and I have to pull off the side of the road. The first time I put it in park and it drove off like nothing ever happens. The second time I pulled over and after I came to a stop I pressed the gas and it did find a gear without putting it in park. 2014 GMC sierra 1500 SLT 6.2 with 3.42 gears.

TJay74 · May 15, 2014

If you all are running larger tires than stock you will have some issues with shifting then. The calibrations profile for shifting is based off of the stock tire size and the speeds that relate to that tier size. Until you correct the tier size in the calibration you will have issues with shifting characteristics.

This is the 4th GM vehicle I have owned with the 6L80E in it, this is a new animal in regards to shifting characteristics compared the previous 4L60E (and other versions) that was used before this. The 6L80/90E transmissions are a clutch to clutch shifting transmission where the previous generation used bands and shells to perform shifts. The tune profile on the new transmission has hundreds if not thousands of variables it uses to shift versus a couple of hundred for the pervious generation transmissions.

GM has to write a calibration that suits the powertrain certification requirements, that calibration is not always going to make every owner happy. Some will always have issues, some will say it shifts to soft, to slow, or too hard or to quick and so on. You have tow options, you either deal with it or you tune it. Not much else you can do other than that.

cory2014 · May 17, 2014

If you all are running larger tires than stock you will have some issues with shifting then. The calibrations profile for shifting is based off of the stock tire size and the speeds that relate to that tier size. Until you correct the tier size in the calibration you will have issues with shifting characteristics.

This is the 4th GM vehicle I have owned with the 6L80E in it, this is a new animal in regards to shifting characteristics compared the previous 4L60E (and other versions) that was used before this. The 6L80/90E transmissions are a clutch to clutch shifting transmission where the previous generation used bands and shells to perform shifts. The tune profile on the new transmission has hundreds if not thousands of variables it uses to shift versus a couple of hundred for the pervious generation transmissions.

GM has to write a calibration that suits the powertrain certification requirements, that calibration is not always going to make every owner happy. Some will always have issues, some will say it shifts to soft, to slow, or too hard or to quick and so on. You have tow options, you either deal with it or you tune it. Not much else you can do other than that.

great info, maybe gm should write a"my truck is brand new and bone stock and my drivetrain shouldn't be clunking tune" .

jrpriest · May 18, 2014

I have a 2014 Denali with the 6.2L and 3.42 gears. I have the delay and surge in the second gear. I have also had issues with the transmission up-shifting to quickly before the engine builds RPMs. On the down shifts you hear the clunk noise. I had 20k miles on the this trunk before I decided the transmission would never learn as promised.

I went for a custom tune for the engine and transmission. It helped the engine tons, but we are still working on the transmission. The transmission tables are very complex. Mike at Vengence PCM in Atlanta makes some adjustment, then i drive the truck a few weeks and go back. Each time it gets better, but it is far from perfect. Lucky for me, Mike has taken this as an R and D project. The new software on the 2014 is much different then the old software.

I will try to keep everyone up tp date with the tune.

scott19677 · May 21, 2014

I guess my transmission is just dumb. 6900 miles and it still hasn't "learned" how to shift into second. Today it shifted so hard I thought someone hit me.

Just put a few thousand more miles on it. so it can learn your driving habits. NOT! How many times have you heard that? That is the only fix I get from the dealer or GM B.S.

pretindica · May 21, 2014

Good luck getting it fixed. I brought mine in for the same issue, was told that "my transmission needs to learn my driving style and to bring it back in if it persists". Well like i told the guy, "I believe you are just delaying the inevitable and will have me driving around pissed off not enjoying my new truck". Anyway I got a recall for an oil pump and I am bringing it in and telling them to fix the transmission again. We will see what excuse they come up with this time. It blows me away that instead of trying to help you out they just BS you out of the door. What good is a warranty if they refuse to fix the issue. I will let everyone know what the excuse is when I get my truck next time as I am certain they will not even attempt to fix it besides "flashing" the computer system.