Low RPM Surging - 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 #1 of 8 (permalink) Old 12-08-2019, 01:00 PM Thread Starter
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Low RPM Surging

My l5p 2019 27k miles l5p when slowing down and there is no load on engine or the wheels pushing it around 1k or whatever rpm surges around 200rpm. Like the tach bounces like it cannot regulate speed well under no load conditions. Has anyone else experienced this? Just curious. Doesnít hurt anything but seems off for a 70k dollar truck ...

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post #2 of 8 (permalink) Old 12-08-2019, 01:54 PM
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Is the bump when the trans does a downshift?

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post #3 of 8 (permalink) Old 12-08-2019, 03:49 PM
 
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I have a '19 and it does the exact same thing. It's usually when I am coasting to a stop, under little or no load. I live on a hill and leaving the house I always coast down the street to a stop sign and the engine "chugs" or "bounces" to a stop. Interestingly, although it can jump up in rpm's it doesn't cause any surge in the drivetrain, I still coast. I have only had it put power into the drivetrain a couple of times and both times I was going up a slight incline coasting to a stop.

The truck has 10k and has done it since day one. I plan on scheduling a visit with the dealer but wanted to get a few miles on the truck to see if if would resolve itself - it hasn't.
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post #4 of 8 (permalink) Old 12-08-2019, 04:02 PM Thread Starter
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Originally Posted by jrmccain View Post
I have a '19 and it does the exact same thing. It's usually when I am coasting to a stop, under little or no load. I live on a hill and leaving the house I always coast down the street to a stop sign and the engine "chugs" or "bounces" to a stop. Interestingly, although it can jump up in rpm's it doesn't cause any surge in the drivetrain, I still coast. I have only had it put power into the drivetrain a couple of times and both times I was going up a slight incline coasting to a stop.



The truck has 10k and has done it since day one. I plan on scheduling a visit with the dealer but wanted to get a few miles on the truck to see if if would resolve itself - it hasn't.


No rough shift not talking about that. Any tranny will do that depending on conditions.

Yes. Exact as you say. It isnít enough surge because of gear itís in and rpm increase isnít enough to influence drivetrain which is good. Strange tho. If you find a resolution or software update please let me and the readers know!!


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post #5 of 8 (permalink) Old 12-08-2019, 04:03 PM Thread Starter
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Originally Posted by redwngr View Post
Is the bump when the trans does a downshift?


Isnít really downshift no. If anything it does it in opposite scenario. Like too high a gear and rpm is low. Noticed it was around 800rpm it did it. But itís small enough doesnít make torque go to wheels generally.


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post #6 of 8 (permalink) Old 12-08-2019, 04:50 PM
 
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Originally Posted by jagster936 View Post
No rough shift not talking about that. Any tranny will do that depending on conditions.

Yes. Exact as you say. It isnít enough surge because of gear itís in and rpm increase isnít enough to influence drivetrain which is good. Strange tho. If you find a resolution or software update please let me and the readers know!!


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I plan on scheduling a visit the first of the new year. I love the truck, coming from a '16 LML. I only have three issues.

1. The engine chugging
2. The transmission shifting is often abrupt and "searching"
3. There seems to be some type of driveline slack or drop coming off a full stop - it's intermittent. Like the driveline is loading up and then releasing - a clunk feel.

Funny, my '16 had a really smooth trans, it shifted predictably. This one not so much.

All of these issues are, (or seem to be), not major. Hopefully I'll have a good report for you guys!
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post #7 of 8 (permalink) Old 12-08-2019, 05:11 PM
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Quote:
Originally Posted by jrmccain View Post
I have a '19 and it does the exact same thing. It's usually when I am coasting to a stop, under little or no load. I live on a hill and leaving the house I always coast down the street to a stop sign and the engine "chugs" or "bounces" to a stop. Interestingly, although it can jump up in rpm's it doesn't cause any surge in the drivetrain, I still coast. I have only had it put power into the drivetrain a couple of times and both times I was going up a slight incline coasting to a stop.



The truck has 10k and has done it since day one. I plan on scheduling a visit with the dealer but wanted to get a few miles on the truck to see if if would resolve itself - it hasn't.
That's interesting that 19 models are still doing that. Me and brother had 17 models and they both did the same thing basically.

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post #8 of 8 (permalink) Old 12-08-2019, 05:35 PM Thread Starter
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Quote:
Originally Posted by jrmccain View Post
I plan on scheduling a visit the first of the new year. I love the truck, coming from a '16 LML. I only have three issues.



1. The engine chugging

2. The transmission shifting is often abrupt and "searching"

3. There seems to be some type of driveline slack or drop coming off a full stop - it's intermittent. Like the driveline is loading up and then releasing - a clunk feel.



Funny, my '16 had a really smooth trans, it shifted predictably. This one not so much.



All of these issues are, (or seem to be), not major. Hopefully I'll have a good report for you guys!


Interesting. I donít think I experience those issues shifts pretty good. But I baby it and mostly highway.

Iím not exactly sure what chugging is but donít think it does?


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