odd (regen?) smell first 15 minutes of driving

[CTown Duramax]

I don't think it's trying to regen if you're smelling it after just two minutes of driving. The engine needs to be up to a certain temperature before it will initiate regen. There's a long list of factors that go into determining when a regen will take place. Read this article - but understand it's for the L5P and not the LM2, so many of the numbers won't be the same, but the principal is similar. https://gm-techlink.com/?p=13566

As @navyseal334 mentioned - take it for a longer trip. If it wants to do a regen, it will finish it up for sure. That said, I think it's a big miss on GM's part to not include in the DIC a "gauge" similar to the DEF level that shows the DPF filter status. If that was there, you could scroll down to it, see that the bars are full and it's ready to regen. I know GM wants the process to be behind the scenes, but it's valuable information and for the people that don't care they can leave it unchecked and never see it.

I use a Banks iDash to monitor my DPF regen status/cycle and it's helped a few times for me to know that a regen is active and that I should take the back roads home. The regen finishes and then I watch the EGT temps drop down and once they are all back to normal temps I shut off the engine. I hate the idea of shutting it down mid-regen or just after one finished and the DPF is still at 1200F...

Can you tell us more about the Banks i Dash or send a link for the one to use with the Tahoe diesel? I too would like some data on the progress of regen cycles. I have been alert to regen c but cannot always (usually, but not always) run to the end of the cycle. With 25k miles, no issues. We're using this Tahoe the same way one would use a gasser. I know ppl voice concerns over short haul driving with the LM2, but the Euros use this type of engine just the way they would use a gasoline engine, all to no ill effect. The diesel is just considered a better and more efficient engine and worth the money.

 

[CTown Duramax]

I'm having a similar issue with my 2024, with about 500 miles on it. A few times I've smelled a raw diesel odor when I turn the engine off. . . . I had a 2020 Sierra HD with the 6.6L Duramax and now have a 2024 with the same engine, and I've never had these issues with those trucks.

Hi. For the first few thousand miles, I experienced some odors, sometimes a melted crayon smell and sometimes more diesel like. They were noticeable but not bad. Then those went away. The only time I notice a smell now is if I have to shut off during regen. None of this has been a problem at all. For me, regen does not occur often, probably every 500 or more miles.

 

[B-train]

I have a 2023 F-450 work truck with the diesel. I can monitor soot load, but it never will tell when regen happens. The way I figured it out was through the instant MPG. When it drops to 7 mpg and doesn't change no matter how light I go on the pedal I know it's in regen. Also, another smell I get during this process, if stopped, is a hot insulation smell from the heat shields around the turbo, etc. I hate it....

Funny how cutting mpg in half for 35 miles is considered clean/efficient. New diesels are such a joke IMO.

I would assume you can monitor instant mpg? Maybe this would help.

 

[StephenPT]

Can you tell us more about the Banks i Dash or send a link for the one to use with the Tahoe diesel? I too would like some data on the progress of regen cycles. I have been alert to regen c but cannot always (usually, but not always) run to the end of the cycle. With 25k miles, no issues. We're using this Tahoe the same way one would use a gasser. I know ppl voice concerns over short haul driving with the LM2, but the Euros use this type of engine just the way they would use a gasoline engine, all to no ill effect. The diesel is just considered a better and more efficient engine and worth the money.

My goal in buying the IDash is to never let a regen not finish its cycle or turn it off right after one. I don't want to pull into the garage with it in a regen cycle, then turn it off and have the whole DPF system sit there at 1100F. While it won't cause problems right away, I'd rather avoid those instances and not cook the hoses and wiring in the area with no ram air flowing through the engine compartment to cool things down.

I've noticed that it takes about 5min for the EGTs to get back down to normal operating temp post-regen. Total regen takes 12-15min so it's really not much of an inconvenience to drive home the long way if I'm in the middle of a regen. I've had the IDash installed for about 5K miles and regen has lined up with arriving home three times in all those miles.

Beyond DPF status, the IDash lets me monitor other parameters that I believe are important to watch, but GM does not give us the information. For example, engine oil temp can get pretty high on the LM2 while towing and I like to know where it's at, especially while pushing a grade. I also like to know which gear I'm in and the IDash will display that. There's a plethora of information the IDash will show you and it can be a bit overwhelming, but I've settled in to the information I want to see and don't bother with the rest.

I bought mine direct from Banks, but I think you can get it on Amazon, EBay, etc. Lots of Youtube videos on it as well.

Banks iDash: SuperGauge & DataMonster

The Banks iDash lets you read and clear diagnostic codes, monitor/record engine sensor data, and control a suite of Banks Electronics, Tuners, and Throttle Controllers. All in a small 52mm gauge, making it the smallest, most powerful plug-n-play OBD-II monitor and control interface on the market.

bankspower.com

 

[steiny93]

I'm having a similar issue with my 2024, with about 500 miles on it. A few times I've smelled a raw diesel odor when I turn the engine off. Then I had it idling in my driveway for a few minutes the other day and the exhaust was pretty stinky (as commented by my wife). I attributed this to what I assumed was regen. Then when I drove it on Friday, I could smell the exhaust when I came to a stop light (all windows were closed), but not after that. I'm going to keep an eye on it and I guess it will have to go into the dealer if it continues. I understand that short drives are not favorable for the regen process, however most of my drives are short. I had a 2020 Sierra HD with the 6.6L Duramax and now have a 2024 with the same engine, and I've never had these issues with those trucks.

update?

raw diesel exhaust smell isn't a regen; that's an exhaust leak
there is a tsb concerning bad flanges on the turbo assembly, dealer has a test procedure

 

[chrisbusnut]

update?

raw diesel exhaust smell isn't a regen; that's an exhaust leak
there is a tsb concerning bad flanges on the turbo assembly, dealer has a test procedure

The dealer tech stated that they didn't smell anything, and said that there were still decals on the exhaust that were probably burning off, since I have such low miles (I've only had the vehicle for about 5 weeks). I've smelled diesel exhaust since getting it back, and agree that it has to be pre-emissions system. If you have access to the TSB and could post, I will print that out and bring it back to the dealer with me. They supposedly checked for exhaust leaks, however I'm not convinced they checked in the engine compartment.

 

[steiny93]

Here is the thread with my experience: https://www.tahoeyukonforum.com/threads/exhaust-smell-in-cab-21-denali.138803/
The techlink is here: https://gm-techlink.com/?p=14365 (appears to be 21 specific)

In my case the exhaust smell occurred randomly, under the hood was much more noticeable. The occurrence seemed to be based on temp of the engine, seemed to happen more often when it was cold (0F) vs warm. After being in a 50F garage, 0F outside, run it through a drive through, it'd usually be pretty bad.

Now, zero exhaust smell in the cab.