PIP5480A - Chugging, Stumble, Harsh Tip- In/Tip-Out - Page 2 - Chevy and GMC Duramax Diesel Forum
L5P TSB (service bulletins, recalls, updates) Postings of Tech Service info for any New L5P engine issues.

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post #11 of 17 (permalink) Old 07-21-2019, 06:02 AM
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Talked to dealer about it. It is like a deer staring into the headlights!
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post #12 of 17 (permalink) Old 09-12-2019, 09:00 AM
 
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My 2019 3500 GMC Denali HD is doing the same thing. Jacksonville, FL
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post #13 of 17 (permalink) Old 10-18-2019, 05:13 PM
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My 2018 and my 2019 have both done this. I have no MIL's though. Talked to the dealer today and he said he thinks the 2019's have a problem with the Throttle Position Sensor and he's going to check it next week. There are times when it's worse than others and I put it in Tow/Haul mode just for the relief. Several times the transmission has down shifted so hard (both 2018/2019) models I swear someone rear ended me. Or it shifts so hard I my u-joints are broken. I never had any of these problems in my 2012 or 2015. I haven't been on the Ford forums but the grass sure is looking greener on the other side. I fell off the Ford bandwagon after my 2004 6.0L fiasco. I can't bring myself to by a Dodge...The definition of "dodge" in the dictionary is "to avoid an encounter with"...
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post #14 of 17 (permalink) Old 12-13-2019, 09:02 PM
 
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Any update on this?
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post #15 of 17 (permalink) Old 12-22-2019, 09:23 AM Thread Starter
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Any update on this?
Nothing yet from GM regarding this widely reported issue.

Not holding my breath that GM will ever fix this problem, especially if the cost to fix the issue is too high.

With the recent strike costs and higher priority recalls on other vehicles, probably take a class-action lawsuit to get GM’s attention once again regarding this issue.

Wish I had better news to offer.

I found this issue only occurs while lightly depressing the accelerator pedal.

Using tow/haul mode and avoiding lightly depressing the accelerator seems to all but eliminate the issue ... for the most part.

However, I do have this long gradual downhill road into town where my truck requires lightly depressing the accelerator pedal to maintain the speed limit and the flow of traffic.

The “chugging / stumble” issue occurs with & without tow haul mode engaged on this downhill unless I manually downshift the truck to keep the rpm’s up.

Sad that we have to engage tow/haul mode and/or change our driving habits to deal with this type of issue on a new $70k truck.

Will update this thread if I hear anything more from GM on this issue.

Appreciate if others will do the same.

For now ... drive it like a race truck to avoid this issue
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2019 Chevrolet Silverado 3500HD 6.6L Duramax (L5P) Crew Cab 4x4 SRW Standard Box High Country Loaded w/ Rear Entertainment Package, Fabtech 4” Suspension Lift w/ Heavy Duty Tie Rods, 35” Tires on 18x8.5 Vision Valor Wheels, Luverne Grille Guard w/ Parking Sensor Relocation Kit, Rhino Roll Bar (Sport Bar 2.0) w/ 8” Hella Off-Road Lights, Banks Derringer / iDash / Intake / DPF Back Exhaust, Fabtech Stealth Shocks w/ Front Limit Straps, Front & Rear Hellwig Sway Bars, Airlift Air Bags w/ Wireless Air, DuraFlap Mud Guards, S&B MAP Sensor Spacer, Kryptonite Heavy Duty Pitman and Idler Arm, Centramatics
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post #16 of 17 (permalink) Old 01-08-2020, 03:49 PM
 
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My 2019 does it as well but I've only experienced it when cold. After it warms up I haven't noticed any problem. Dealer claims not to have ever heard of it before.
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post #17 of 17 (permalink) Old 01-12-2020, 05:20 PM Thread Starter
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My 2019 does it as well but I've only experienced it when cold. After it warms up I haven't noticed any problem. Dealer claims not to have ever heard of it before.
https://gm-techlink.com/?p=10589

Transmission Torque Request Override

With 445 horsepower and 910 lb.-ft. of torque, the new engine has increased horsepower and torque compared to the previous diesel engine. After slowing down and then pressing on the accelerator or when changing gears (such as when plowing snow), a short delay in response may be noticed. This delay is designed to help protect the drivetrain from a sudden torque increase. The Transmission Control Module (TCM) overrides the torque request from the driver via the accelerator pedal in order to control engine torque to a level that protects the transmission hardware when making a gear change.

The request override may be noticed most often when a 6th-to-4th gear downshift occurs when applying the accelerator at 70% or greater between 45 and 55 mph (72 and 88 km/h) or when applying the accelerator after a moderate to aggressive braking maneuver from 20-30 mph (32-48 km/h) down to 0-10 mph (0-16 km/h) where a 3rd-to-1st gear downshift occurs.



Transmission Adapt Learns

On a vehicle with relatively low miles, or with low miles since the TCM was reprogrammed, the transmission may seem to shift hard or the engine may seem to flair between shifts. There also may be bumps or jerks when the vehicle downshifts. If this condition is found, it may be necessary to perform a transmission shift adapt quick learn using GDS2.



Change in Torque Converter Lock-up Strategy

In the new 6-speed transmission, the torque converter now locks in 3rd gear instead of 5th gear. As a result, the vehicle will feel more responsive when accelerating from 3rd gear and higher and transmission downshifts may be more noticeable.

On very light accelerator pedal applications when the torque converter is locked, a hesitation, shutter, or stumble may be felt. This feeling is a result of the very high torque the Duramax is capable of producing at low engine speeds as well as the engine being directly coupled to the rear drive wheels. When the torque converter clutch is not locked, it can serve as a viscous damper between the engine and rear drive tires. When the torque converter clutch is locked, 100% of the rapidly increasing torque is delivered to the rear tires.

2019 Chevrolet Silverado 3500HD 6.6L Duramax (L5P) Crew Cab 4x4 SRW Standard Box High Country Loaded w/ Rear Entertainment Package, Fabtech 4” Suspension Lift w/ Heavy Duty Tie Rods, 35” Tires on 18x8.5 Vision Valor Wheels, Luverne Grille Guard w/ Parking Sensor Relocation Kit, Rhino Roll Bar (Sport Bar 2.0) w/ 8” Hella Off-Road Lights, Banks Derringer / iDash / Intake / DPF Back Exhaust, Fabtech Stealth Shocks w/ Front Limit Straps, Front & Rear Hellwig Sway Bars, Airlift Air Bags w/ Wireless Air, DuraFlap Mud Guards, S&B MAP Sensor Spacer, Kryptonite Heavy Duty Pitman and Idler Arm, Centramatics
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