21NE and GMC Canyon

[Finman]

Picking up our 21NE in June and we’re looking into getting a 2021 GMC AT4 Canyon with the Duramax diesel.
What are peoples experience with the setup?
Anyone have two kiddos in car seats in the second row, if so, how cramped is it?
Lastly what hitch step up do you all recommend?
Thanks!

[salmo7000]

I tow a well-equipped 19 with a Chevy Colorado diesel. I know of several on this forum who tow a 21 with either a Colorado or Canyon. My Colorado tows my 19 effortlessly up and down the mountains of the western US, and I think it’s a great combination. I have Escape’s Fastway weight distributing hitch, which works well. No doubt a Canyon diesel would work well towing a 21NE.

I don’t have kids or any experience with car seats so can’t really comment on that. The back seat seems pretty roomy to me. I have the crew cab.

One of the best things about these small diesels is their fuel efficiency, both towing and not. I’m also much happier driving a mid size pickup. But, you have to periodically add DEF, and it seems to me the emission systems on these trucks could present problems down the road, so be sure to read up on them before making a final decision. So far mine has been perfect though, it’s about to turn over 45,000 with thousands of miles towing.

[Finman]

Thanks for that great information.
If the White Bird in your location is referring to a N. Idaho location, how is it towing up and down white bird pass and the Lewiston grade? We’ll be traveling throughout the PNW, with a base in Spokane.

[salmo7000]

Yes, same White Bird! Truck pulls the 19 up White Bird and Lewiston grades at around 55 - 57 mph, which is as fast as I want to go. It could possibly do it faster as it’s not floored at this speed, but I don’t want to push it. RPMs 2,000 - 2,500. Towing up these grades has been the only time I’ve felt like the truck has had to work hard. Most of the time it just hums along effortlessly.

The one thing I forgot to mention is these diesels have an exhaust brake. Going up White Bird grade is one thing, going down it is quite another, yikes. But, no yikes with the exhaust brake! It holds the speed around 52 mph the whole way down, total control without having to smoke or even use the truck or trailer brakes. It works much better than gearing down and is a definite selling point.

So yep, my truck has done a great job towing for me so far on these long, steep grades.

[Nrgtic4]

We also tow a 21 with the Canyon Crew cab diesel using the ETI fast away hitch. We’ve gone cross country over mountains several times and everything works together great! Never a scary moment and best yet, we average 18 mpg towing.

[BritCanuck]

Can I ask you folks with the Duramax what your truck payload is? And what model Canyon you have? Thanks !

[splitting_lanes]

Originally Posted by BritCanuck

Can I ask you folks with the Duramax what your truck payload is? And what model Canyon you have? Thanks !

2021 Canyon crew cab long bed diesel, high elevation package (elevation with leather seats).
Payload capacity is 1366

[salmo7000]

Originally Posted by BritCanuck

Can I ask you folks with the Duramax what your truck payload is? And what model Canyon you have? Thanks !

2017 Colorado Duramax, 4X4 crew cab long bed. 1,390.

[Ops]

I don't own a diesel (short of my Kubota tractor), but have in the past prior to DPF requirements coming into play. I've been quite interested in the pros vs cons of diesel ownership, and on balance, they are clearly designed for the job they are designed for. Grunt work and fuel economies vs gasoline.

My commenting is directed to those owners of modern diesel vehicles. Many are unaware of DPF maintenance regeneration, which if diesel owners do not follow said maintenance, could create a deep hole in the bank account. Following is an auto engineer & online journalist from Australia (colourful commentary warning) who explains (colourful terms) what a diesel owner should do to fully enjoy the benefits of such a vehicle.

https://www.youtube.com/watch?v=DSXiQvTaP9A

Again...colourful comment warning for those of sensitive sensibilities.

[Johnspierce]

Originally Posted by Ops

I don't own a diesel (short of my Kubota tractor), but have in the past prior to DPF requirements coming into play. I've been quite interested in the pros vs cons of diesel ownership, and on balance, they are clearly designed for the job they are designed for. Grunt work and fuel economies vs gasoline.

My commenting is directed to those owners of modern diesel vehicles. Many are unaware of DPF maintenance regeneration, which if diesel owners do not follow said maintenance, could create a deep hole in the bank account. Following is an auto engineer & online journalist from Australia (colourful commentary warning) who explains (colourful terms) what a diesel owner should do to fully enjoy the benefits of such a vehicle.

... removed youtube link

Again...colourful comment warning for those of sensitive sensibilities.

That was an informative video -- thanks!

The baby Duramax diesels do have an automatic Regen mode. It works best under load at highway speeds. In other words, regen will be happening when you are towing! I've read a lot on Chevy Colorado/Canyon forums about regeneration. The Duramax twins have a warning indicator come on when it's in "regen" mode. The only time you should have to take your vehicle into a dealer for a "manual regen" is if you get a warning light telling you so.

We have a VW diesel which my wife drives and she uses it in a very low speed
commute about 14 miles per day. At around 80,000 miles, the manifold had so much carbon built up it had almost no power at all. We had the VW mechanic de-carbon the manifold (not cheap) and it's going strong at 95k miles.

[JeffreyG]

2021 Colorado CCSB Z71 diesel. 1380 lb cargo capacity.


I have a banks iGage in a defroster vent pod that I use to monitor the data available on the OBD II canbus. Interesting stuff. I've had the truck for 1540 miles and it is at 98% full right now, so about to start its third regeneration.


Incidentally, I spent 9 years designing the first aftertreatment systems for HD diesel engines (this being DPF, DOC, SCR etc) and so I know what they are and how they work. I bought the OBD monitor to see how my friends at GM are doing it (I probably know several of them).

[splitting_lanes]

Originally Posted by JeffreyG

2021 Colorado CCSB Z71 diesel. 1380 lb cargo capacity.


I have a banks iGage in a defroster vent pod that I use to monitor the data available on the OBD II canbus. Interesting stuff. I've had the truck for 1540 miles and it is at 98% full right now, so about to start its third regeneration.


Incidentally, I spent 9 years designing the first aftertreatment systems for HD diesel engines (this being DPF, DOC, SCR etc) and so I know what they are and how they work. I bought the OBD monitor to see how my friends at GM are doing it (I probably know several of them).

I’m planning to install a provent air/oil separator on the cv line, are you doing anything like that? I’m real curious to know the thoughts of someone who designed the emissions systems on these.

[JeffreyG]

Originally Posted by splitting_lanes

I’m planning to install a provent air/oil separator on the cv line, are you doing anything like that? I’m real curious to know the thoughts of someone who designed the emissions systems on these.

I put a better separator on the crankcase vent line when I got my truck. In the HD diesel world we have spent a lot of time and effort on very effective systems to pull liquids out of the crankcase vent once these systems had to be closed. I'm kind of surprised at how little effort the passcar guys have put into this and I'm not judging their system to be acceptable. It's unusual for me to second guess, but the separator that is on the LWN valve cover is not going to do anything.

In general I really do not want oil mist to be passed through the crankcase system as this oil mist is really undesirable:
1) I don't want it fouling the compressor wheel.
2) I don't want it fouling the charge air cooler and lowering performance
3) I don't want it mixing with EGR and making a soot/oil paste in the intake and on the intake valves.
4) Every bit of oil mist burned in the engine contributes ash content collected by the DPF. The more oil mist burned, the sooner the DPF needs to be cleaned or replaced.


I don't know how this one played out between the cost target team and the engineers, but realistically the design they have does not favor the customer.

[JeffreyG]

A bit more on the LWN. It has an ATS system that is really common in passenger cars. These systems go - DOC - SCR - ASC - DPF. There are two key factors going on here that reflect that most passenger car systems experience short trips and highly transient cycles:
1) The SCR is in front of the DPF. This lets the SCR heat up faster, which gets it online earlier and allows the engine to make more NOx (= more efficient).

2) But - The DPF is downstream of the SCR which means it sees no NO2. Soot in a DPF can be removed through passive oxidation via NO2. But in the LWN system this will never happen because the SCR will have removed the NOx ahead of the DPF. What this means is in the end, all of the collected soot has to be removed in active regeneration events. In turn, that means these active regenerations have to happen more often which burns more fuel.
3) The common trade calculation in passcar is, the duty cycles are so transient / cold that passive regeneration isn't going to happen anyway. So better to focus on engine out NOx and just rely on active regeneration.


HD diesel engines run a DOC - DPF - SCR - ASC configuration and rely heavily on passive regeneration of the DPF. They often run 10,000 miles or more between active regenerations. But they have a much different duty cycle. They have periods of long highway running at much higher average load.


All this is interesting because I think the new GM 3.0 diesel is DOC - DPF - SCR - ASC. I'd be really interested to see how that works.

[splitting_lanes]

Originally Posted by JeffreyG

I put a better separator on the crankcase vent line when I got my truck. In the HD diesel world we have spent a lot of time and effort on very effective systems to pull liquids out of the crankcase vent once these systems had to be closed. I'm kind of surprised at how little effort the passcar guys have put into this and I'm not judging their system to be acceptable. It's unusual for me to second guess, but the separator that is on the LWN valve cover is not going to do anything.

In general I really do not want oil mist to be passed through the crankcase system as this oil mist is really undesirable:
1) I don't want it fouling the compressor wheel.
2) I don't want it fouling the charge air cooler and lowering performance
3) I don't want it mixing with EGR and making a soot/oil paste in the intake and on the intake valves.
4) Every bit of oil mist burned in the engine contributes ash content collected by the DPF. The more oil mist burned, the sooner the DPF needs to be cleaned or replaced.


I don't know how this one played out between the cost target team and the engineers, but realistically the design they have does not favor the customer.

I was thinking the same thing after reading everything I could find about the emissions system, or as you refer to it, the ATS.

Keep the oil mist out of the turbo, intercooler, and away from the EGR, and the motor should last longer.

I kinda figured maybe GM doesn’t want these things to last as long as they potentially could... can’t sell a new truck to someone that can get a half million miles on the one they got. That, and good air/oil separators are expensive, and probably not the only problem to solve.

I always second guess, even myself.

[BritCanuck]

Thanks for the payload figures folks.

Is the Canyon comfortable over long distances? Read lots of complains of uncomfortable seats on the older models.

R.e. The DPF regen issue....has a simple solution once out of warranty...delete and tune kit. ��

[splitting_lanes]

Originally Posted by JeffreyG

A bit more on the LWN. It has an ATS system that is really common in passenger cars. These systems go - DOC - SCR - ASC - DPF. There are two key factors going on here that reflect that most passenger car systems experience short trips and highly transient cycles:
1) The SCR is in front of the DPF. This lets the SCR heat up faster, which gets it online earlier and allows the engine to make more NOx (= more efficient).

2) But - The DPF is downstream of the SCR which means it sees no NO2. Soot in a DPF can be removed through passive oxidation via NO2. But in the LWN system this will never happen because the SCR will have removed the NOx ahead of the DPF. What this means is in the end, all of the collected soot has to be removed in active regeneration events. In turn, that means these active regenerations have to happen more often which burns more fuel.
3) The common trade calculation in passcar is, the duty cycles are so transient / cold that passive regeneration isn't going to happen anyway. So better to focus on engine out NOx and just rely on active regeneration.


HD diesel engines run a DOC - DPF - SCR - ASC configuration and rely heavily on passive regeneration of the DPF. They often run 10,000 miles or more between active regenerations. But they have a much different duty cycle. They have periods of long highway running at much higher average load.


All this is interesting because I think the new GM 3.0 diesel is DOC - DPF - SCR - ASC. I'd be really interested to see how that works.

DPF = Diesel particulate filter
SCR = Selective .....
DOC = ?
ASC = ?

Where is the DEF injected on these, which system?

Ps. I knew from reading your posts last year that you knew more about these engines than me, so when I read you were getting a Colorado, I knew my Canyon was a great choice. (Diesel)

[JeffreyG]

Originally Posted by splitting_lanes

DPF = Diesel particulate filter
SCR = Selective .....
DOC = ?
ASC = ?

Where is the DEF injected on these, which system?

Ps. I knew from reading your posts last year that you knew more about these engines than me, so when I read you were getting a Colorado, I knew my Canyon was a great choice. (Diesel)

DOC - Diesel oxidation catalyst. Will burn off CO and HC, can be used as a burner by injecting fuel to make heat over the DOC. Also will convert NO => NO2 for the purpose of passive soot oxidation in the DPF.

DPF - Diesel particlate filter. filters out soot, which has to be burned off. Burning can be slow, passive reaction with NO2 which happens around 300-400C or faster, active reaction with O2 which will only happen above 550C.

SCR - Selective catalytic reduction. Uses ammonia as a reductant to drive the reducing reaction of NO and NO2. Ammonia is formed by hydolysis of urea (DEF) which is injected upstream of the SCR.

ASC - Ammonia slip catalyst, often zone coated onto the end of the SCR. Another oxidation catalyst to burn off any excess ammonia.

All this complexity in diesel is required for two reasons:
1) The three way catalyst found with gasoline engines handles both CO/HC oxidation and NO reduction at the same time. But this catalyst only works in a stream with no free oxygen. Diesel engines are lean burn engines, so there is always free oxygen in the exhaust.
2) Diesel engines have particulate levels demanding a filter. I'd argue that the newer direct injection gasoline engines should also be fitted with particulate filters because they make a lot of sub 2.5 micron particles, but so far no regs.

[JeffreyG]

Originally Posted by splitting_lanes

I kinda figured maybe GM doesn’t want these things to last as long as they potentially could... can’t sell a new truck to someone that can get a half million miles on the one they got. That, and good air/oil separators are expensive, and probably not the only problem to solve.
.

It's not so much an engineered obsolescence as it is that a vehicle has to have cost and life targets. So you can't make everything cost too much so that the vehicle lasts 500,000 miles. Nobody would buy it because it would be too expensive.

What can be challenging for engineers is deciding how long things will last based on the data they have. All of their testing is accelerated, which is not good at finding how some things age and fail.

But in general they do design all systems to last for however long the design target says it should. Their definition of how long that is, and what level of performance may be different from yours.

[splitting_lanes]

Originally Posted by JeffreyG

It's not so much an engineered obsolescence as it is that a vehicle has to have cost and life targets. So you can't make everything cost too much so that the vehicle lasts 500,000 miles. Nobody would buy it because it would be too expensive.

What can be challenging for engineers is deciding how long things will last based on the data they have. All of their testing is accelerated, which is not good at finding how some things age and fail.

But in general they do design all systems to last for however long the design target says it should. Their definition of how long that is, and what level of performance may be different from yours.

Thank you for all the detailed explanation. Now I’m curious as to what improvements can be made to the ATS so that it doesn’t shorten the life of the engine, and what systems in the ATS will fail first, or not fail at all.

It’s my understanding that some parts of the ATS system are required, and if they fail the engine won’t run, not because it can’t run, but because it’s programmed that way. This understanding may be something I deduced by reading about delete and/or defeat systems — which I’m not interested in doing, unless it comes down to being able to make it to a repair shop.

I’m software programmer that’s built a number of engines, and even worked on nitro burning funny cars in the pits. So I have a background in engines and systems programming, but this is my first diesel, and I plan to tow a 5.0 across the states a few times. It seems preparation would be paramount.

I feel like we should start a new thread just to discuss ATS, so if you want to... do it, and I’ll ask questions, and I’m sure others will too. It’s great to have these discussions with someone who understands these systems.