Anyone happy with their L5P - Page 5 - Chevy and GMC Duramax Diesel Forum
2017-19 GM T-K2 Platform Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #41 of 206 (permalink) Old 07-06-2018, 12:06 PM
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Had my 2018 for about 2500 miles and the gas mileage is moving in the right direction. Can’t get over the power on takeoff from the 18 compared to my 15. Time will tell on tunes 🙏🏼.

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post #42 of 206 (permalink) Old 07-06-2018, 12:23 PM
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I'm loving my 2018 3500 high country dually so far. I'm obviously down on power compared to my 2012 lml but it's stock with a warranty so I don't feel like I have to baby it and worry about it all the time. I've got 2600 miles on mine all towing and I'm impressed with the stock power and fuel mileage has been about the same loaded.
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post #43 of 206 (permalink) Old 07-07-2018, 10:29 PM
 
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Well new here and to a GM product, First off I love the drive/power and second the mileage has beat my other trucks. It is still very new 1200kms but i put on about 50,000 kms a year and drive shitty roads alot of the time, so time will tell if this truck has what it takes for me to call a good work truck.

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post #44 of 206 (permalink) Old 07-11-2018, 09:48 PM
 
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Before I say a thing about my 18 GMC 3500 I will explain my first experience with a duramax. I am not a big complainer and I loved my 05 Chev 2500 LLY. I loved it even though I had many issues with it. Injectors that were under warranty, blown head gaskets that left me and my family stranded in Richfield Utah for 7 days, a blown transmission (mostly my fault cause I was hard on it), and the day after I sold it to a cousin a seized oil pump that starved the turbo and destroyed it. In all spent some big bucks on that truck but I really enjoyed that truck.

The L5P I would gladly give back to the dealer. Many minor things that are not worth complaining about here but the transmission shifting alone drives me completely nuts!!! This tcm is not programmed well at all. It amazes me that GM would deliver a vehicle like this. Slipping at low speed, erratic shifting, long gaps in shifts (35-45mph), harsh down shifts (almost like the trans is in relearn). Love the 6 speed though 🙂 makes all the difference on hwy vs my old 5 speed.

Dealer tried to duplicate but if course couldn't and even told me that it must be because I drive my truck hard which is not the case. I baby my new $60k truck. I want it to last. These issues of course happened the next day after getting my truck back from the dealer. Haven't towed yet with 4500 miles. Horrible mpg... But big power is good 🙂

I really hope GM puts out a fix for this trans.

I've been a GM fan starting with my 98 Silverado. Trusted that this would be a solid truck. Now I am regretting the purchase.

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post #45 of 206 (permalink) Old 07-12-2018, 02:34 AM Thread Starter
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Quote:
Originally Posted by MOTOvated490 View Post
Before I say a thing about my 18 GMC 3500 I will explain my first experience with a duramax. I am not a big complainer and I loved my 05 Chev 2500 LLY. I loved it even though I had many issues with it. Injectors that were under warranty, blown head gaskets that left me and my family stranded in Richfield Utah for 7 days, a blown transmission (mostly my fault cause I was hard on it), and the day after I sold it to a cousin a seized oil pump that starved the turbo and destroyed it. In all spent some big bucks on that truck but I really enjoyed that truck.

The L5P I would gladly give back to the dealer. Many minor things that are not worth complaining about here but the transmission shifting alone drives me completely nuts!!! This tcm is not programmed well at all. It amazes me that GM would deliver a vehicle like this. Slipping at low speed, erratic shifting, long gaps in shifts (35-45mph), harsh down shifts (almost like the trans is in relearn). Love the 6 speed though 🙂 makes all the difference on hwy vs my old 5 speed.

Dealer tried to duplicate but if course couldn't and even told me that it must be because I drive my truck hard which is not the case. I baby my new $60k truck. I want it to last. These issues of course happened the next day after getting my truck back from the dealer. Haven't towed yet with 4500 miles. Horrible mpg... But big power is good 🙂

I really hope GM puts out a fix for this trans.

I've been a GM fan starting with my 98 Silverado. Trusted that this would be a solid truck. Now I am regretting the purchase.
Sorry to hear you r having issue, I posted this thread primarily because all I was reading was bad stuff about the L5P, coming from a 2015 LML I was skeptical about my purchase, so far no issue and almost 2500 miles. Still haven't got the warning about DEF low, regens every 170 miles or so. My tranny shifts solid, no issues in town or on the highway. Good luck getting your issues resolved.

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Last edited by mzodarg; 07-12-2018 at 06:48 AM.
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post #46 of 206 (permalink) Old 07-12-2018, 05:42 AM
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The shift quality in my 2018 has the same overall feel as my prior 2006 LBZ/Allison 6 speed. It certainly has no slippage (I assume you are feeling the unlocked torque converter in first because any slipping in gear will quickly set a DTC for incorrect ratio as determined by the various shaft speed sensors) and the shifts are sure and not erratic. Are you sure your TCM has the latest updates?

All but one of my regens has occurred on the interstate but if you are in regen in town I expect even with the latest updates the downshifts while slowing will feel different since the engine is being held well above normal base idle speed during regen.

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post #47 of 206 (permalink) Old 07-12-2018, 06:51 AM Thread Starter
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Originally Posted by TwinTurboLML View Post
I'm loving my 2018 3500 high country dually so far. I'm obviously down on power compared to my 2012 lml but it's stock with a warranty so I don't feel like I have to baby it and worry about it all the time. I've got 2600 miles on mine all towing and I'm impressed with the stock power and fuel mileage has been about the same loaded.
Like you, I came from a tuned LML not sure if this L5P is down on power comparatively or is it just down on noise and smoke.

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post #48 of 206 (permalink) Old 07-12-2018, 08:38 AM
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Quote:
Originally Posted by MOTOvated490 View Post
Before I say a thing about my 18 GMC 3500 I will explain my first experience with a duramax. I am not a big complainer and I loved my 05 Chev 2500 LLY. I loved it even though I had many issues with it. Injectors that were under warranty, blown head gaskets that left me and my family stranded in Richfield Utah for 7 days, a blown transmission (mostly my fault cause I was hard on it), and the day after I sold it to a cousin a seized oil pump that starved the turbo and destroyed it. In all spent some big bucks on that truck but I really enjoyed that truck.

The L5P I would gladly give back to the dealer. Many minor things that are not worth complaining about here but the transmission shifting alone drives me completely nuts!!! This tcm is not programmed well at all. It amazes me that GM would deliver a vehicle like this. Slipping at low speed, erratic shifting, long gaps in shifts (35-45mph), harsh down shifts (almost like the trans is in relearn). Love the 6 speed though 🙂 makes all the difference on hwy vs my old 5 speed.

Dealer tried to duplicate but if course couldn't and even told me that it must be because I drive my truck hard which is not the case. I baby my new $60k truck. I want it to last. These issues of course happened the next day after getting my truck back from the dealer. Haven't towed yet with 4500 miles. Horrible mpg... But big power is good 🙂

I really hope GM puts out a fix for this trans.

I've been a GM fan starting with my 98 Silverado. Trusted that this would be a solid truck. Now I am regretting the purchase.


There is a reflash you can do at the dealer for the transmission, and this might help fix some of your complaints. But honestly the transmission will get better and better as you get more miles,
I remember some times where the transmission would shift so harshly that I was really worried about the transmission, I never did the transmission reflash from gm, and honestly I can say that the issues go away, I have 25,000 miles now, and it really drives nice, the 3rd to 4th shift is a little odd sometimes, but overall the thing shifts awesome now. I let my buddy take it for a spin once, and the first thing he said after he went wot for a few seconds was, “wow this thing shifts so smooth”, and that was when the truck was basically brand new still, it will get better with time.
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post #49 of 206 (permalink) Old 07-12-2018, 06:08 PM
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Upshifts are nice and predictable on mine. likes to shift at the 2's. 32 mph, 42 mph, 47 mph, basically is a 5 + 2 shift point. Occasionally it will downshift and TC feels like its not unlocked b/c it literally feels like you got rear ended.

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post #50 of 206 (permalink) Old 07-12-2018, 06:10 PM
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Originally Posted by jlawles2 View Post
Upshifts are nice and predictable on mine. likes to shift at the 2's. 32 mph, 42 mph, 47 mph, basically is a 5 + 2 shift point. Occasionally it will downshift and TC feels like its not unlocked b/c it literally feels like you got rear ended.


I’ve had to look in the rear view a few times because of this. Felt like someone smacked the hitch.


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