2009 6l80e surging issue

XJNKY · October 4, 2016

Hi all,

Pseduo newbie here. Not new to mechanics or even GM trucks, just new to the GMT900 platform. Hoping you guys could help me out.

I've searched google and this forum looking for answers, but have not been able to find anything similar to what I'm experiencing. Please forgive me if I missed an obvious thread. I'm not entirely sure what I need to be searching for. Was hoping you guys could steer me.

We bought a low miles (71K) 2009 Silverado from a dealer recently, and it started having transmission issues within 1,000 miles. It came with a dealer-provided lifetime power-train warranty, but so far, the experience with the dealer defines the very essence of poor experience. They basically drive it a couple miles, not even far enough to get it warmed up, and then spit out the trusty old "could not replicate". So, I'm looking for a direction to point them, or maybe even a TSB?

2009 Silverado 1500 CCSB Z71, LC9/6L80E. Factory tow package.

What is happening is this: When the transmission has warmed up, and you're going generally over 50mph, but sometimes slower, when coming to a stop the truck will surge and try to pull for a brief moment. And sometimes it will do this 2-3 times in rapid succession. It isn't really that the engine is surging, it feels more like the torque converter is locking/ unlocking rapidly. But, it will pull, even with you off the gas, and holding the brake. And if you watch the tachometer, it seems to synchronize with the downshifts the transmission makes as you're slowing. In a few cases, it has taken up all the drivetrain slack pretty suddenly and led to some fairly audible clunking/jerking. I should note, this transmission also has the very hard 2-3 shift, but, again, the dealer "can no replicate", at least not on their dime.

Now, I saw some reference on a Pontiac forum, under the 6l80E in the G8, reference a software update released for 2009 trucks, but could not find anything about it anywhere else. I asked the dealer to check for software updates, but was told there was none.

Has anyone had a similar experience with the TC locking/unlocking?

Thanks in advance.

MaverickZ71 · October 5, 2016

What you are experiencing is a very common occurrence. Unfortunately, harsh 1-2 shifts, early upshifts into overdrive (gears 5-6), surging when coming to a stop, and the infamous driveshaft thunk/clunk when stopping/starting can all be a part of the GMT900 ownership experience. As well as the AFM oil usage problem. My truck has been to 3 dealers and I have been told "yeah, they all do that" by the service managers.

XJNKY · October 6, 2016

Hey Maverick, Thanks for the response. I've read about everything you mentioned except this surging issue. Everything else seems to be pretty common, and from what I've found everything else on the list has a TSB to address it. By the way, you forgot the awesome lifter tick on startup.

If it's not too much to ask, right off hand do you have any links to anything regarding the surging? I haven't been able to find anything relevant. I mean, I'm glad to hear that it isn't just ours, but it does it really bad sometimes. Like, I'm afraid of how this is going to play out in the winter.

Side note, the dealer's first diagnosis was slip/stick condition on the slip yoke (how that explains surging, they never were able to explain). So they "removed, sanded, lubricated, reinstalled". About 600 miles later, our transfer case was empty and all the fluid was coating the underside of the rear of the truck. I crawl under, and they had taken a grinder to the slip yoke to remove the rust. Not wise to take a grinder to a dynamic sealing surface. It's been a 3 week ordeal getting that fixed, and involved a different dealer for a second opinion and the implied threat of a lawyer to get them to fix it. On Tuesday, they tell me they replaced the seal, but can't replace the slip yoke because it's a one piece drive shaft (we all know that's not true). After an email, they suddenly learned how.

So, having owned this truck 6 weeks now, they've had it for 3. Worst dealer experience of my life. And they seem wildly inept, and have no issue with outright lying, in writing. So, anything I could use to corner them and get them to fix this would be great.

Thanks

MaverickZ71 · October 11, 2016

The surging problem has been discussed from time-to-time here and on other forums. I know that the National Highway Traffic Safety Administration (NHTSA) had an open ticket on it at one time as well. I never heard of a consensus on a 'fix' for this problem. You can read more about it here:

http://www.gm-trucks.com/forums/topic/138481-2011-sierra-surging-ahead

And we didn't cover all of the common GMT900 problems, you can read more on that here:

http://www.gm-trucks.com/forums/topic/165322-gmt-900-common-problems/?hl=common+problems

XJNKY · October 12, 2016

Thanks Maveric.

It's back in the shop, again. Lost oil pressure on the way to work this morning.

And thanks for the Sierra thread. I had not found that one. I'm not sure if it makes me feel any better or not, but at least I know it isn't just mine. I've been asking every person I find with one if theirs does it. Everyone looks at me like I've got something growing out of my head.

Thanks again.

MaverickZ71 · October 13, 2016

My truck does the surging-while-trying-to-stop thing sporadically, especially here lately. It is maddening, and once in a great while another family member will drive the truck, and I have to remind them to always be prepared for it.

Good luck with the loss of oil pressure. You may have already seen the thread pinned to the top of this forum on that issue. If not, it is here:

http://www.gm-trucks.com/forums/topic/169782-attention-anyone-with-oil-pressure-issues/

There seem to be a lot of oil issues with these trucks. I was test driving a used 2007 Silverado and it said "stop engine immediately, low oil pressure" or something like that about 1/2 mile from the dealer. And the oil on the dipstick was full. So I bought a new '09 instead, and have still had problems.

I think these oil problems are one reason why GM came out with the mandated usage of Dexos-1 rated motor oil beginning in 2010. I have found that using Pennzoil Platinum 5W-30 and AC Delco PF48 (NOT the PF48E--I won't use the new 'e-core' filters) filters work best to minimize the cold-start AFM lifter tick in my truck.