Diesel Question

[Kenmotorist]

I have older diesels, '94 Chevy 6.5 turbo. They're pigs at highway speed, but get 17mpg compared to 11 in my gas trucks.
If you need to accelerate to pass on the interstate, diesels are not for you. They're great pulling a load or for mileage at steady state, but passing is just not their forte.
They'll keep speed even with a load, but they don't pick up speed quickly.

True for larger capacity diesels but not the 3.0 duramax. It’s a light duty diesel tuned to behave like a gas truck but with stellar fuel economy

 

[Pressureangle]

True for larger capacity diesels but not the 3.0 duramax. It’s a light duty diesel tuned to behave like a gas truck but with stellar fuel economy

Yes, and I'm all for unleashing the diesel beasts. Modern electronic diesels with variable turbos are pretty amazing, but nobody's stock Duramax will win a drag race with a 6.0 gas motor. It will get twice the fuel mileage trying, though.

 

[StephenPT]

Do you carry DEF with you regularly? Just on long trips? Or not all all?

Never carried extra. As mentioned, when you’re doing regular driving usage rate is about ~7K miles per tank of DEF.

Towing is considerably more usage, but you’ll get a warning on the dash when you’re 1K miles from empty. Our range while towing is ~350 miles so the next time we hit a Pilot, Loves, etc. we pull over for diesel and I grab a jug of DEF.

The DEF is a non-issue. People that don’t own this motor will make comments about the inconvenience. Under normal driving I probably refill my washer fluid more often than I do DEF. Towing is about 5-6 times a year for us and if it’s a trip <1K miles I won’t need to get DEF until I get home.

 

[blkonblk]

have a 23 yukon and added a banks power pedal and no issues at all, feels like a sports car lol

 

[stedanrac]

@blkonblk - Does the Banks Power Pedal affect mileage?

I will echo all of the previous comments on performance vs. mileage... When I drive my 23 Tahoe, its usually on long highway trips. I keep the RPMs just under 1500 and the MPG is up around 30, all while hauling six people in comfort. Its a beautiful thing.

When I want to zip around, run yellow lights, get pinned in my seat, I take my electric car out.

 

[dukecharmary]

Sounds like you found a good dealer/salesman if they honestly admitted to you the issues with the 6.2. Most dealers are “deaf” to issues and it’s always the first time they’ve heard of something if a customer brings it up.

My only guess on the delay in diesel orders is capacity constraints as they wind down LM2 production and go to 100% LZ0. The LZ0 has been out for awhile now in the pickup trucks and the only thing I’ve heard about it is that DEF consumption rate is higher than previous model years (LM2).

The LZ0 added a second DEF injector and is setup to meet more stringent NOx emissions.

Its just doesn't make sense, the yukons have had the LM2 diesel for some time now and the LZ0 has been out in the sierra for some time too. How can there be a 6 month delay in this replacement. Sure sounds like either a major glitch or GM has just dropped the rollout ball with poor planning. What am I missing?

 

[EGTroup]

I have never driven a diesel so I don't have 1st hand knowledge of this. But while going through many threads here, I have come across some who complain that the diesel seems to lag when attempting to pass on the interstate. Or is sluggish when getting on the gas. That seems to be contradictory to what I heard, that the diesel makes it's torque and power early. I would think when you step on the gas and it downshifts, you would get more power which would make passing another vehicle seem effortless.

What am I missing?

On the diesel, you do not want to downshift to pass or accelerate. Just apply more fuel petal pressure and let the lower RPM torque contribute to acceleration. My 2023 Yukon Denali Duramax is great on the highway and I have no complaints about acceleration when pulling out onto road into traffic or when passing.

 

[chrisbusnut]

Having come from a 6.2 to the Duramax, there is definitely a difference with passing on the highway. I had to pass a slower moving vehicle on a two lane highway and the timing to pass was longer than I had anticipated, putting myself in an uncomfortable position with the oncoming car (yes, I passed legally). That never would have been the case with the 6.2. That said, the advantages of the Duramax far outweigh the poor gas mileage and known mechanical issues with the gas engines.

 

[EGTroup]

Its just doesn't make sense, the yukons have had the LM2 diesel for some time now and the LZ0 has been out in the sierra for some time too. How can there be a 6 month delay in this replacement. Sure sounds like either a major glitch or GM has just dropped the rollout ball with poor planning. What am I missing?

I suspect climate scam globalists and EPA pressure to kill diesels and all internal combustion engines and migrate to electric has caused poor decision making by weak management. GM and Ford have lost $Billions building EVS that no one wants even when heavily subsidized. Now those subsidies are going to end.

 

[bryan8252]

On the diesel, you do not want to downshift to pass or accelerate. Just apply more fuel petal pressure and let the lower RPM torque contribute to acceleration. My 2023 Yukon Denali Duramax is great on the highway and I have no complaints about acceleration when pulling out onto road into traffic or when passing.

Can you please explain why I wouldn’t want the diesel to downshift in that situation?

 

[martinajm]

Can you please explain why I wouldn’t want the diesel to downshift in that situation?

Or how one would even do this? As far as I know, there is no way to prevent the downshift unless you VERY SLOWLY apply petal pressure.

 

[StephenPT]

Or how one would even do this? As far as I know, there is no way to prevent the downshift unless you VERY SLOWLY apply petal pressure.

Just set cruise control at your desired speed and the truck will do the rest. I have a Banks I-Dash and on my towing layout I have the gear indicator. On flat ground going 62mph it's in 9th gear. Light grades it will stay in 9th, but eventually downshift to 8th and then 7th if it really needs to on a steep grade. I think one time I had it go into 6th and that was a steep grade. The engine monitors the load %, speed, rpm, etc. and determines the best gear for the situation. Watching the gear indicator while towing and not towing, this engine does NOT downshift until it absolutely needs to.

The 3.0 Duramax produces 80% of its torque at 1250rpm and 100% of its torque at 1500rpm.

 

[martinajm]

On the diesel, you do not want to downshift to pass or accelerate. Just apply more fuel petal pressure and let the lower RPM torque contribute to acceleration. My 2023 Yukon Denali Duramax is great on the highway and I have no complaints about acceleration when pulling out onto road into traffic or when passing.

Just set cruise control at your desired speed and the truck will do the rest. I have a Banks I-Dash and on my towing layout I have the gear indicator. On flat ground going 62mph it's in 9th gear. Light grades it will stay in 9th, but eventually downshift to 8th and then 7th if it really needs to on a steep grade. I think one time I had it go into 6th and that was a steep grade. The engine monitors the load %, speed, rpm, etc. and determines the best gear for the situation. Watching the gear indicator while towing and not towing, this engine does NOT downshift until it absolutely needs to.

The 3.0 Duramax produces 80% of its torque at 1250rpm and 100% of its torque at 1500rpm.

My comment about how to do it was based around "apply more fuel petal pressure" but not downshifting. Applying more pressure usually results in a downshift.

My experience with using cruise control while towing is vastly different than yours @StephenPT . I tow a relatively heavy and tall (alot of drag) boat at highway speeds. I usually lock out 10th gear. I find that when using CC that the transmission is searching for gears quite often. Without CC, I can control the shifting with petal pressure pretty well. This obviously results in more speed variability vs CC, but I figure it is better on the transmission.

 

[JayceeP]

Can you please explain why I wouldn’t want the diesel to downshift in that situation?

Low end torque… it pulls very well at lower rpm’s…. Different than a gas engine. You’d need to test drive it to understand but these trucks rarely downshift on the highway unless you smash the pedal. Up and down moderate hills…. Very little downshifting.

 

[Fless]

What's the diff between a flower petal and a fuel pedal? (Rhetorical question)

If I sold flowers and car parts would I be a peddler of petals and pedals?