2022 LP5 Loud Air Noise on Throttle and Bad Fuel Economy

aleeuw · January 3, 2023

Hey all,

Tried searching for similar issue, unable to find anything.

Noticed about a month ago, now starting again, my fuel economy would start to drop dramatically and when I hard accelerate there is a very loud air sucking or blowing noise coming from the engine bay. Took it into the dealer to have it inspected and they could not find any issues. Checked all turbo hoses and did find any loose connections or leaks and of course, when they drove it, they could not replicate the sound. Normally when I let off the throttle, my economy goes to 99mpg but when I notice this issue it only goes to about 65mpg max.

Could it be trying to regen the DPF? I don't normally drive more than 20 minutes in the morning and 20 minutes in the evening to and from work. In summer the truck sees a lot more because I am towing a camper hundreds of miles.

Not sure what other information I can provide to the community to explain the issue more but I am concerned that it could lead to more issues. I only have about 7,600 miles on the truck right now.

Thanks in advance for the help!

Random · January 3, 2023

When mine goes into regen the engine sound changes and my fuel economy tanks. I don't notice any weird blowing noise though, so it may or may not be related. If you have an OBDII reader handy, you may be able to pull live data and see soot levels and regen status when it's acting up vs. running normal.

aleeuw · January 3, 2023

I may be totally oblivious but how do you know when it goes into regen? There is nothing on the DIC showing % or regen that I am aware of.

newdude · January 3, 2023

Sounds like a regen to me. The only signs are elevated idle in Drive when stopped, and big fuel economy drop. A full regen should last 10-20 minutes at the most and usually occur once per tank of fuel.

The noise is probably because these engines use a throttle body in the intake that can be manipulated for regen operations. Normal driving its open all the time. The throttle blade can close to increase backpressure.

Edited January 3, 2023 by newdude

Random · January 4, 2023

5 hours ago, aleeuw said:

I may be totally oblivious but how do you know when it goes into regen? There is nothing on the DIC showing % or regen that I am aware of.

Sadly there isn't anything the truck will display that will let you know when it's in regen, that's why I suggested the reader to be able to see that data.

aleeuw · January 4, 2023

13 hours ago, newdude said:

Sounds like a regen to me. The only signs are elevated idle in Drive when stopped, and big fuel economy drop. A full regen should last 10-20 minutes at the most and usually occur once per tank of fuel.

The noise is probably because these engines use a throttle body in the intake that can be manipulated for regen operations. Normal driving its open all the time. The throttle blade can close to increase backpressure.

Thanks for the insight! New to diesel and still learning all of the different noises and fun extras over the gassers. I am guessing that has to be it as it did it on the way home from work last night once up to temp and this morning was back to normal.

aleeuw · January 4, 2023

10 hours ago, Random said:

Sadly there isn't anything the truck will display that will let you know when it's in regen, that's why I suggested the reader to be able to see that data.

I have a reader, but its a bit older. I will have to plug it in and see if it shows all of that data. Otherwise, tempted to get an Edge Insight or something alike. Thanks for the help!

Random · January 4, 2023

7 hours ago, aleeuw said:

I have a reader, but its a bit older. I will have to plug it in and see if it shows all of that data. Otherwise, tempted to get an Edge Insight or something alike. Thanks for the help!

For as often as I'm looking at the trucks data I really need to invest in something like the Edge Insight myself. Then I'd at least be able to save which data points I want to look at instead of scrolling through the laundry list of stuff my reader provides. I like to know what "normal" operation looks like so I can see when something goes wrong or isn't right.

XY74 · January 5, 2023

19 hours ago, Random said:

For as often as I'm looking at the trucks data I really need to invest in something like the Edge Insight myself. Then I'd at least be able to save which data points I want to look at instead of scrolling through the laundry list of stuff my reader provides. I like to know what "normal" operation looks like so I can see when something goes wrong or isn't right.

The Generous Mother has decreed that you don't need to know anything! It would seem to be simple to program a few more parameters into the existing system for display. I guess they figure it would cause more trouble than they want to deal with from customers worrying too much.

GMCustomerService · January 9, 2023

On 1/3/2023 at 8:58 AM, aleeuw said:

Hey all,

Tried searching for similar issue, unable to find anything.

Noticed about a month ago, now starting again, my fuel economy would start to drop dramatically and when I hard accelerate there is a very loud air sucking or blowing noise coming from the engine bay. Took it into the dealer to have it inspected and they could not find any issues. Checked all turbo hoses and did find any loose connections or leaks and of course, when they drove it, they could not replicate the sound. Normally when I let off the throttle, my economy goes to 99mpg but when I notice this issue it only goes to about 65mpg max.

Could it be trying to regen the DPF? I don't normally drive more than 20 minutes in the morning and 20 minutes in the evening to and from work. In summer the truck sees a lot more because I am towing a camper hundreds of miles.

Not sure what other information I can provide to the community to explain the issue more but I am concerned that it could lead to more issues. I only have about 7,600 miles on the truck right now.

Thanks in advance for the help!

This is certainly not what we like to hear, aleeuw. Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your 2022 GMC Sierra 2500 Denali. To do so, please send an email to [email protected] with ATTN: aleeuw/GM Trucks in the subject line.

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