Poor shifting. Converter lock-up? Active Fuel Management?

BlackOps · December 25, 2015

I have a 2015 Sierra Denali 5.3L with a 2.5" leveling kit and 295/55/20 Toyo MT (approximately 33"), no tuner, factory gears, etc. and I don't know if the problem is stemmed from the tires, but I am absolutely disappointed in the way the truck shifts.

It seems like it shifts way too fast, especially from 1st to 2nd, and sometimes it feels like the converter is locking up way too soon because the truck just lugs down. It might be that active fuel management is kicking in way too soon.

Anyone else experiencing this? Is it my tires? Is there a quick fix? More complicated than that? Tuner? Gears? Disable active fuel management? Is there a recall, TSB, etc. that the dealer can fix this issue?

BlackOps · December 27, 2015

So many views, yet no light shined on my situation. I'm thinking it's a combination of everything I mentioned. Active fuel management kicking in too often/soon, torque converter locking up too often/soon, and the transmission shifting too soon. Apparently my truck comes with a steeper gear than other trims (3.42), but my truck just seems sluggish because of the the issues mentioned.

07Softail · December 27, 2015

Yeah...it's been covered a Million+1 times.

RT

txab · December 27, 2015

Try a tune to clean your problems up

mgu1995 · December 27, 2015

I have the same problem on my 2014 Silverado when it shifts and the problem is between 1st gear to 2nd gear idk what it could be???

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I have a 2.5 rough country level on 33/12.50/20 my tires and it has the same problem as ur truck in shifting its sluggish!

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BlackOps · December 27, 2015

Will a handheld type tuner do the trick or does it need a custom dyno tune?

chuckl1218 · December 27, 2015

I don't have a "silver bullet" for you, but some observations...my truck, (2014 Silvy, 5.3L, 3.42 rear, stock tire size, no lift or level) was also sluggish. I watched the AFM switching in the DIC and observed that it did not kick in while accelerating. But when cruising around at 35-55, it did switch back and forth a lot. Also when cruising at highway speeds, it would go in and out while cruising flat terrain. But the issue that I was concerned with, was when accelerating while cruising at 35-55; there was always a big lag. I used a Range AFM delete device which my son had to test this and was greatly impressed with how much better it ran. I then purchased a Diablo Intune to just turn off AFM. I am now very pleased with the overall drivability. At least until I get a Diablew tune...

There are several threads about tunes that you should review. In each case, the tuner enhances shifting characteristics and reviews are very positive. I think you have a lot of other factors in play with the tires, lift, etc. that play into this. And no, I don't think there is a TSB to fix this.

Rkaroll953 · December 28, 2015

They all seem to shift like this. its set from the factory like this to get the best mpg possible and yea it does suck. sometimes i think my old chevy with a t350 shifts nicer. i drive around in M5 so it doesn't go into v4. a tune does wonders but good by warranty if you blew the tranny or something.

bigsapper · December 28, 2015

When I was stock, I always felt the 1-2 shift happened to quick. This was problematic when I was turning right out of a parking lot. Expecting a decent pedal but shifts and bogs down in front of traffic.

Using tow/haul helps as it holds the gears longer before shifting.

robvas · December 28, 2015

It seems like it shifts way too fast, especially from 1st to 2nd, and sometimes it feels like the converter is locking up way too soon because the truck just lugs down. It might be that active fuel management is kicking in way too soon.

The converter doesn't lock up in 1st or 2nd gear

I also doubt AFM is coming on that early

BlackOps · December 29, 2015

I assure you guys I'm not imagining things. There's a lot of confusion with my truck. No check engine lights, but it's awful when it comes to AFM and the tranny. There's no doubt that something happens and then you can feel and hear the truck lug down. I have a Corsa exhaust, so there's no missing it. I have to push on the pedal a little harder and it comes out of its rut somewhat. The 1-2 shift is too soon, I know it. I know what torque converter lock up and that's exactly what it feels like. The only time the truck feels like it's somewhat running like it's suppose to is if I give it a moderate amount of throttle where the rpms get up there and no worries about shifting too soon or the AFM kicking in. The AFM in my opinion should only kick in at higher gears, like 5th or 6th. When you're actually up there in mph, say...50-60 mph. It's pointless and quite annoying at slow speeds.

Anyway, there's a lot of talk about Diablo tuners, yet everyone seems to refer them to Diablew and Intune. When I went to Diablo Sport's website, these are the only models offered for a 2015 Sierra 5.3L:

Trinity T1000

i2 I2030

Txjose · December 29, 2015

When I was stock, I always felt the 1-2 shift happened to quick. This was problematic when I was turning right out of a parking lot. Expecting a decent pedal but shifts and bogs down in front of traffic.

Using tow/haul helps as it holds the gears longer before shifting.

Thats exactly what i feel!!!! 33s and 3.08s dont help my case either. Did a tune clear that right up?

bigsapper · December 29, 2015

Thats exactly what i feel!!!! 33s and 3.08s dont help my case either. Did a tune clear that right up?

Stall & BBP tune.

Willshire · December 29, 2015

Has a lot to do with the steep first gear to begin with. It's 4.027:1 compared to the 4l80e in 2008 and down trucks that had a 2.48 1st gear. Which is almost the same as the second gear of the 6 spd (2.364). Also, gears 5 and six are overdriven which will provide slightly less performance on acceleration, 3.08 gears and 33" tires will also make it doggy. 33" tires on any factory gearset will seem sluggish i think