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2015 Truck 6.2 L Engine, 8L90E Transmission troubles, problems, fixes

NiceDay

By NiceDay
in Troubleshooting & Recalls

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NiceDay New Member

NiceDay

Posted
Posted

Hello

 

Thinking about purchasing a new GM truck. I am wondering if anyone is having any problems with their new 1/2 ton trucks. Is GM having any problems with the 6.2 Liter Eco Tec 3 engine or still having some troubles with the new 8L90E Transmission. Other troubles and their solutions would be intresting too.

 

It would be nice to learn in advance what to expect, will it be a wonderful smooth ride. Should I expect a few fixable bumps along the way or am I entering a nightmare ride.

 

Thanks in advance for your input.

Success stories are certainly welcomed for a well rounded view.

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Rawyzf Senior Enthusiast

Rawyzf

Posted
Posted

Lots of threads, enjoy the reading.

CounterMeasure Enthusiast

CounterMeasure

Posted
Posted

Short version of the 6.2L: I've found its a great engine. Better mileage and much more power than my previous truck.

 

Short version of the 8L90: Besides tolerance issues in some units, the problems lie in its software. The fixes are either wait for various software updates from GM now and then, which reset your transmission back to learn mode for the next 1800 miles or so (per GM directly), or get a custom tune and risk your warranty.

 

If you test drive one, I think its best to find one used, or one with at least a couple hundred miles on it to know what to expect. My experience is that when in learn mode, the first few miles are smooth because the transmission is ultra conservative on its shift pressures. Then it starts pushing its limits and gets really bad, then starts cleaning them up for the next 500+ miles. Meanwhile, it stays in "hunt mode".

JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted

this may be a moot point, but the 6.2 and 6 speed with the 3.42 rear end in my 2014 is an aweome combination. had the 5.3 with a 4 speed with the 3.42 and it was a dog, always trying to find a "happy gear" to be in. the 14 is a hot rod for such a large truck. 23+ mpg has been the best 50 mile average so far.

f8l vnm Senior Enthusiast

f8l vnm

Posted
Posted

It's all tuning , the trans itself is good one.

My 2014 Sierra with 6.2 , has been confused from day one.

NiceDay New Member

NiceDay

Posted
  • Author
Posted

It's all tuning , the trans itself is good one.

My 2014 Sierra with 6.2 , has been confused from day one.

 

Hello --- Thanks to all who have responded so far.

 

Could you explaine more -- "has been confused from day one"

 

I see your truck is not a 2015 vehicle and asume it does not have a 8 speed 8L90E transmission. Is your truck a 1/2 or 3/4 ton truck with a 6 speed transmssion? Can you explain in more detail what your expercening.

 

Thanks

Randys Denali Enthusiast

Randys Denali

Posted
Posted

I got my 2015 Sierra Denali (6.2L, 8 speed, 2WD, crew cab, 6.5' bed) on November 5th 2014.

  • In December 2014, my navigation system started showing me driving 50 miles away from my actual location and the onstar stopped working. It took a few weeks to get new parts, but they had to replace my entire main computer that handles the nav and onstar.
  • Approximately January/February 2015, my transmission was jerking when I would come to a stop. It feels as though it's holding on to 2nd gear until I come to a complete stop and then it jerks it into 1st gear and jolts my truck forward. There is also a audible clunking/banging noise coming from the transmission when this happens. ----- I took my truck in to the GMC dealer and they explained they explained they applied an update to the 'transmission control module' (but the technician also . That seemed to get rid of the problem. SIDE NOTE: When I took my truck in, they did not drive the truck or have me drive it with a technician riding along to understand what I was describing. They simply took the truck into the bay and reset the 'learning' feature on the transmission. After they applied the update/reset the learning feature, I drove the truck with a technician and I confirmed the problem was no longer noticeable.
  • Approximately early June, I took my truck in for an oil change, at which point I was notified of a recall on the 'Torque Converter Clutch'. They fixed the recall by applying a update to the torque converter clutch and that caused the problem to reappear in my transmission again. I took my truck in this morning to have it checked out again. I asked for a technician to drive my truck prior to fixing anything. The technician stated he did feel what I am talking about and wasn't immediately sure of what could be causing the problem. I was told they don't have time to find out what the problem is today and was asked to come back in two days when they have time.

The transmission is great up-shifting and down-shifting on all gears from 2nd through 8th gear. 1st gear is the only time I have issues. As far as the engine, the 6.2L has plenty of power and it feels smooth. I've been averaging 14-16mph. It's a great looking truck and I get a lot of people complimenting me on it; but it's pretty embarrassing coming to a stop and having the truck jerk forward as if i'm just learning to drive.

 

I hope this helps

iCryWheniGoPoop Enthusiast

iCryWheniGoPoop

Posted
Posted

Bought my 15 LTZ 6.2 on 6/10, all I can say is that the tranny is perfect aside from me getting use to the constant shifting. Absolutely love my truck!

Kander41 Enthusiast

Kander41

Posted
Posted

I purchased my 6.2/8 speed in the end of May and love it. Always seems to be in a gear you need and has been smooth when compared to my old '07 4 speed. My wife and family can barely feel it shift through the gears without looking at the tach. The others mentioned a new truck off the lot will not feel the same as mine took a few 100 miles to wake up.

 

Sent from my HTC One using Tapatalk

bass mechanic Enthusiast

bass mechanic

Posted
Posted

just got my Denali 8 speed and i have no complaints. i do notice what others are talking about but in my case it is very minimal, not a big deal and i plan to wait till i have more miles before looking for a fix.

otherwise the transmission drives great! i don't know which i like better, the mag ride or the 8 speed. but both together with the 6.2 make the truck an absolute blast to drive.

i do wish there was no down shift switch in the gas pedal as i have to remind myself to push it harder when it stops if i am trying to get the max acceleration out of it. but otherwise with normal driving its almost enough to make me give up driving a car the rest of the days of the week.

  • 1 month later...
jetfixer737 Enthusiast

jetfixer737

Posted
Posted

I don't know guys, I had the TCC software update done on mine about 3 weeks ago. Most of how the trans operates seems pretty much the same (No real issues) however, my 2-1 downshifts intermittently (I HATE that word) have become VERY hard. The other night when getting off the freeway when coming to a stop it downshifted SO hard that it actually chirped the tires. I took it to a dealer the next day for its first oil change with 6000 miles on the odo. I told the service writer the downshift story and all he said was "Really? Hmmm" and pretty much dismissed it as probably needing another software update "If they ever come up with one"

A few more downshifts like that one last Thursday night and I'm afraid I'm gonna bust something...

iCryWheniGoPoop Enthusiast

iCryWheniGoPoop

Posted
Posted

Got my Recalls done today, it is definitely better.

Recall 15178/15389

 

 

Sent from Off Driller Side

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