2024 GMC Sierra 1500 Elevation 2.7L Turbomax with Possible Torque Converter Issue

Jason Ridge · August 5

I have a 2024 GMC Sierra 1500 2.7L Turbomax. I've posted in another section about an oil leak and defective main engine seal I had repaired. Since the repair and re-assembly of the truck, I've noticed what seems to be an overly aggressive torque converter. That's to say, it sometimes acts like a teenager learning to drive a manual transmission...not entirely releasing the clutch or "riding the clutch" a bit. Starting out with normal acceleration, it eases into first, then as it shifts to second, it seems to not engage (or be engaged) all the way in 2nd...staying at a near constant rev speed, then shifts to third, then fourth, and so on. Past 3rd gear, it's fine. But it's the first two to three gears that seem to be "clutch-heavy". When I first purchased it, before it was repaired and reassembled, it seemed much tighter without all the heavy clutch/torque converter aggression. It's not slipping, but just seems to be overly focused on trying to make it smooth...which turns out to be super annoying. Anyone else with the same truck experience this? I posted this quick video so you can try to hear what I'm experiencing. Perhaps this is the way it is and it's just going to drive me crazy. But I wanted to check.

Video below. Sorry about the VO...but wanted to point out when it was doing what I'm seeing/hearing.

Edited August 5 by Jason Ridge

customboss · August 6

2 hours ago, Jason Ridge said:

I have a 2024 GMC Sierra 1500 2.7L Turbomax. I've posted in another section about an oil leak and defective main engine seal I had repaired. Since the repair and re-assembly of the truck, I've noticed what seems to be an overly aggressive torque converter. That's to say, it sometimes acts like a teenager learning to drive a manual transmission...not entirely releasing the clutch or "riding the clutch" a bit. Starting out with normal acceleration, it eases into first, then as it shifts to second, it seems to not engage (or be engaged) all the way in 2nd...staying at a near constant rev speed, then shifts to third, then fourth, and so on. Past 3rd gear, it's fine. But it's the first two to three gears that seem to be "clutch-heavy". When I first purchased it, before it was repaired and reassembled, it seemed much tighter without all the heavy clutch/torque converter aggression. It's not slipping, but just seems to be overly focused on trying to make it smooth...which turns out to be super annoying. Anyone else with the same truck experience this? I posted this quick video so you can try to hear what I'm experiencing. Perhaps this is the way it is and it's just going to drive me crazy. But I wanted to check.

Video below. Sorry about the VO...but wanted to point out when it was doing what I'm seeing/hearing.

TCM attempting to adjust to engine repairs and your ECM relearning too. If it’s not smoother in 50 miles take back to dealer to reset both computers.

Edited August 6 by customboss

Jason Ridge · August 6

9 minutes ago, customboss said:

TCM attempting to adjust to engine repairs and your ECM relearning too. If it’s not smoother in 50 miles take back to dealer to reset both computers.

Thanks for the note. Both have been reset and updated. No change. Going back to the dealership tomorrow. We'll see what they say. They tend to feel that there's nothing wrong, but it simply can't be right. It's such a weird way to shift...we'll see.

customboss · August 6

55 minutes ago, Jason Ridge said:

Thanks for the note. Both have been reset and updated. No change. Going back to the dealership tomorrow. We'll see what they say. They tend to feel that there's nothing wrong, but it simply can't be right. It's such a weird way to shift...we'll see.

If it re learns it should do it fast.

customboss · August 6

We need newdude on this one. It’s under warranty. If dealer not meeting needs can you get to another? GM service engineer come visit? At Cummins we came to you with serious issues but of course our dealers were mostly company owned.

newdude · August 6

17 hours ago, Jason Ridge said:

I have a 2024 GMC Sierra 1500 2.7L Turbomax. I've posted in another section about an oil leak and defective main engine seal I had repaired. Since the repair and re-assembly of the truck, I've noticed what seems to be an overly aggressive torque converter. That's to say, it sometimes acts like a teenager learning to drive a manual transmission...not entirely releasing the clutch or "riding the clutch" a bit. Starting out with normal acceleration, it eases into first, then as it shifts to second, it seems to not engage (or be engaged) all the way in 2nd...staying at a near constant rev speed, then shifts to third, then fourth, and so on. Past 3rd gear, it's fine. But it's the first two to three gears that seem to be "clutch-heavy". When I first purchased it, before it was repaired and reassembled, it seemed much tighter without all the heavy clutch/torque converter aggression. It's not slipping, but just seems to be overly focused on trying to make it smooth...which turns out to be super annoying. Anyone else with the same truck experience this? I posted this quick video so you can try to hear what I'm experiencing. Perhaps this is the way it is and it's just going to drive me crazy. But I wanted to check.

Video below. Sorry about the VO...but wanted to point out when it was doing what I'm seeing/hearing.

14 hours ago, Jason Ridge said:

Thanks for the note. Both have been reset and updated. No change. Going back to the dealership tomorrow. We'll see what they say. They tend to feel that there's nothing wrong, but it simply can't be right. It's such a weird way to shift...we'll see.

Hmm. Removing the transmission "could" have resulted in resetting shift adapts, but in the process of removing and reinstalling it to perform the rear main job, there is nothing that needs to be done to the transmission besides remove it and reinstall it, and then top off any fluid loss.

On the 8L80 in your truck, the torque converter can apply in any gear, 1st through 8th. The 8L90 in the earlier trucks, same thing.

Honestly? Watching your brief video, and having driven my 2022.5 (with the HO now called Turbomax) for 24,000mi, it seems to be operating normally. Mine does this and has since day one. I will hop in a couple at work today (drove the spare car) and try and compare.

Its possible yours has since day one, but it went un-noticed until they had your truck apart, which could have heightened your awareness of how the truck operates. I don't mean this in any sort of mean way, but its a common occurrence. Its just like people who never watch their oil pressure gauge or their battery gauge and then question why the battery gauge swings its voltage readout during vehicle operation or why their oil pressure gauge spikes past a certain RPMs.

Edited August 6 by newdude

Jason Ridge · August 6

Thanks for the reply and information. I did not notice it before the reassembly/repair, but it could very well have been there. Just hard to miss (or have missed). This just seems like improper operation to me...not quite engaging 2nd gear. The rest of the way through 3rd, 4th, 5th, etc...seems fine. It's just the 1st to 2nd to 3rd transition that seems off...like 2nd gear is not entirely engaged (like the clutch not being released). If you accelerate hard right at the transition point from 1st to 2nd...it does engage quite hard and abruptly.

I was just curious about others' experiences. This seems like something that could be fixed by a GMC software update to reprogram the shift points (or process), but I'm obviously not a mechanic.

There is one other perhaps related issue that I have that I did not include in my post. When parking my truck and just rolling forward...it will slow almost to a stop, there is a clicking noise from the area of the transmission, and then the truck lightly lurches forward. I've almost hit my garage wall a few times. The video below shows this (you'll mostly notice the clicking because I have my foot on the brake to keep it from hitting the wall...so any movement is stopped by that.) Probably unrelated, but who knows...

newdude · August 6

4 hours ago, Jason Ridge said:

Thanks for the reply and information. I did not notice it before the reassembly/repair, but it could very well have been there. Just hard to miss (or have missed). This just seems like improper operation to me...not quite engaging 2nd gear. The rest of the way through 3rd, 4th, 5th, etc...seems fine. It's just the 1st to 2nd to 3rd transition that seems off...like 2nd gear is not entirely engaged (like the clutch not being released). If you accelerate hard right at the transition point from 1st to 2nd...it does engage quite hard and abruptly.

I was just curious about others' experiences. This seems like something that could be fixed by a GMC software update to reprogram the shift points (or process), but I'm obviously not a mechanic.

There is one other perhaps related issue that I have that I did not include in my post. When parking my truck and just rolling forward...it will slow almost to a stop, there is a clicking noise from the area of the transmission, and then the truck lightly lurches forward. I've almost hit my garage wall a few times. The video below shows this (you'll mostly notice the clicking because I have my foot on the brake to keep it from hitting the wall...so any movement is stopped by that.) Probably unrelated, but who knows...

If you were already rolling into the garage from driving, its downshifting from 2nd into 1st that click. I haven't found one that doesn't do it, mine does it as well. I've always come to a stop first when pulling in to make sure my mirrors are clearing the door frame, and stopping completely lets it shift with no movement like that.

I didn't have a chance today to hop in a new one but I'll try tomorrow for the 1-2-3 thing you've got going on, and try and maybe video. Or when I get home I'll try my truck.

newdude · August 12

Alright, managed to put these together quick with my truck. Did the best I could to replicate your acceleration rate in the first one. 24,000mi, its operated like this since the day I bought it, as has every other 2.7 I've driven at work.

First video mid way through 2nd to the top of the 2-3 shift you can hear/see the converter lock but almost instantly it locks it grabs 3rd.

Second video I didn't come to a complete stop so it starts in 2nd. You can see it jump up under acceleration and right about the 2500rpm mark it starts to lock up.

Edited August 12 by newdude

Jason Ridge · 2024-11-21T16:51:51Z

Since it's been a while, I thought I'd give a quick update. The 2024 GMC Sierra is back in the service department for repairs. The issues with the transmission continued to evolve over the last couple of months. Most recently while driving the truck between 30-50 MPH at low RPM (1200-1500) on a fairly flat road at a constant speed, the entire truck would shake rather severely, just for a moment. The issue was repeatable by just a slight feathering of the throttle at a steady speed. The service rep who rode with me to experience the issue diagnosed it as "TCC shutter." The dealership is replacing the torque converter to address the issue. I'm scheduled to get the truck back late Friday, so we'll see if this addresses the TCC shutter as well as some of the other experiences with the transmission that might have been torque converter-related.

I'll post an update in a few days.