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  1. #1

    Cool Burb Displacement on Demand

    Being an Oldie Newbie to this forum, I thought I would jump in with a few comments and questions concerning my 07 Suburban LTZ 5.3 (Black of course). My wife and I love this new (nearly) burb and so do our ten English Bulldogs (We breed and show, but that's another story). This LTZ has DOD, Displacement on Demand (4 cylinders/8 cylinders). I like the concept and have been pleasantly surprized at how smoothly it transitions. After the engine is sufficiently warmed up, the DOD functions OCCASIONALLY between 40 and 55 mph on a smooth, level, or decending roadway. I drive with a very light pedal foot. If I am very careful with the throttle and there is no headwind, it will remain on 4 cylinders for 45 seconds at best. BUT, while on 4 cylinders, the instant economy display shows better than 30 (sometimes over 35 ) mpg. While holding the throttle steady by foot, it will transition back to 8 cylinders and the instant econ display shows 20 to 21 mpg. The problem is it will remain in 8 cylinders mode for several minutes before going back to 4 . Since the 4 cylinder operation is so smooth (with steady throttle), I would like to have more control over this . I think I like that 30+ mpg on a big Burb. Has anyone found a way to alter or enhance the E40 ECU without adversely affecting the overall operation? Thanks for a Great Forum!! Phil and Joyce

  2. #2

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    i just wish it would be in 4cyl mode while it sits in park idling.

  3. #3

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    I don't have an answer to your question but another question related to the new burbs. My brother just got a brand new Yukon Denali XL, the GM version of the burb and it also has the DOD. He was also impressed by how smoothly it shifted from one mode to the other. However, one thing he told me about it has me a bit puzzled. He said that it has all time all-wheel drive. I asked him if he meant that it was always in Auto-4WD mode where it would automatically shift into 4WD when needed but he said that he thought it was always in 4WD - there are no buttons to change it to auto or 2WD.

    This seems to run counter to the idea of making the vehicle DOD, a fuel saving measure. I would think that being in all time 4WD would decrease mileage. Is your new burb like this and if so, what do you think about this feature?

  4. #4

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    No, my burb is straight 2 wheel drive. That was a feature I insisted on. I took a long look at the new Denalis with their all-wheel drive feature and that quickly turned me off. I live in Florida so why do I need all-wheel drive. I could understand having it in North Dakota. As for the question concerning All-Wheel drive verses 4 wheel drive, they are different. All of the All-wheel drive vehicles I know of are not selectable. That is, they can not be shifted out of all-wheel mode. (Audi, VW, Mercedes, Mazda, and many others). They are heavier, very expensive to repair, cause a ten percent reduction in fuel mileage, more expensive to buy, slightly more sluggish handling, slightly noisier and more tire wear plus higher insurance rates. I agree with you on "why build a vehicle with all-wheel drive, then give it DOD" trying to make it more economical. I think Chevy took the right approach by offering their top end burb (LTZ) with a choice of 2 wheel drive or 4. The dealers seem to be selling many more of the 2 wheel drive models. GMC would be wise to do the same with the Denali, (in my opinion). But you know what they say about "opinions". Phil

  5. #5

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    mu burb is 4wd, i can select 2hi, auto, 4hi and 4 lo. imo just because one would want 4wd or awd doesn't mean they can't use or want DOD.

  6. #6

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    Quote Originally Posted by esponet View Post
    mu burb is 4wd, i can select 2hi, auto, 4hi and 4 lo. imo just because one would want 4wd or awd doesn't mean they can't use or want DOD.
    I agree. I think that DOD seems like a great feature but if I were to buy a 4WD vehicle with it, I would also want the option to switch to 2hi, 4hi, 4lo or auto. Likewise, it would be nice if the DOD offered more in the way of driver control of this feature.

    If I lived in Florida, I would probably also opt for the 2WD version as long as it had the limited slip differential (does it?) and I did not plan on doing much travelling to northern states in the winter time. The 2WD suburbans make great tow vehicles in good road conditions.

  7. #7

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    Quote Originally Posted by IrishBrewer View Post
    My brother just got a brand new Yukon Denali XL, the GM version of the burb and it also has the DOD. He was also impressed by how smoothly it shifted from one mode to the other. However, one thing he told me about it has me a bit puzzled. He said that it has all time all-wheel drive.
    Are you sure it has DOD? What year is it?

    I just bought a 2007 Yukon Denali XL and it does NOT have DOD. The 2008 spec list on the Denali engine says that the 6.2L V8 does not have DOD either.

    The Denali does have AWD. It is on all the time and cannot be disabled. Unlike the part-time 4wd in the other trim levels, it does not have a low-speed transfer case for true off-roading.

  8. #8

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    Quote Originally Posted by Stargazer View Post
    Are you sure it has DOD? What year is it?

    I just bought a 2007 Yukon Denali XL and it does NOT have DOD. The 2008 spec list on the Denali engine says that the 6.2L V8 does not have DOD either.

    The Denali does have AWD. It is on all the time and cannot be disabled. Unlike the part-time 4wd in the other trim levels, it does not have a low-speed transfer case for true off-roading.
    He just got it brand new a couple weeks ago so it may be an '08 or an '09 if they are out yet. He seemed certain that it has DOD although when I asked him what size engine it had in it, he wasn't sure. It is a company vehicle assigned to him so he wasn't involved in purchasing it otherwise, I'm sure he would have known.

  9. #9

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    Greetings Phil and Joyce, and welcome aboard, finally. Better Old Newbies than Lurkers.
    Quote Originally Posted by joyphil View Post
    ...I think I like that 30+ mpg on a big Burb. Has anyone found a way to alter or enhance the E40 ECU without adversely affecting the overall operation? Thanks for a Great Forum!! Phil and Joyce
    I think it's a case of not being able to see the forest because of the trees. GM is trying to acclimate us to full-time 4WD and variable power levels. I suspect, in the not too distant future, we'll no longer have direct drive. If you think wheel bearing prices have sky rocketed since the introduction of the modular hub unit, just wait until the same unit includes an electric drive motor.
    I'm old enough to remember when a 20 MPG VW Beetle was considered an economy car. Hopefully I'll live long enough to see a 35 MPG all-wheel drive Suburban considered a gas hog.
    Are we having fun, yet?

  10. #10

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    Thanks for the "Welcome Aboard", Zippy!! Your comments about the 20 mpg VW brought back memories. I remember when VW was first imported to the U.S. and you could buy one for $1200. The auto labor unions were having a fit. (and gas was 22 cents a gallon). AARRGGHH. I was driving a German built Isetta 300 (BMW) at the time (ugly as sin). 300 c.c. one cylinder engine. I think it would get almost 30 MPG. Terrible mileage when you think about it. Top speed about 50 mph. Wish I had that car now (worth more than my BURB). I saw you are a former Corvair Corsa Turbo owner. I Loved them too. Mine was a '65 Corsa 140 (4 carburetors). Don't ask the MPG . Not good. My '63 Impala S.S. actually got better mileage. (wish I still had that car too). Anyway, to stay on track, Someone was asking about the 6.2 liter GMC engine and DOD. I was under the impression that the 6.2 was only offered with variable valve timing and not DOD. Maybe that is only with Chevy and not GMC. The variable valve timing is another feature I like but wasn't available on my 5.3 (at that time). I have heard rumors that GM is working hard on the "Camless" engine, similar to some of the diesels offered by Cummins. Electronically controlled valves would be a big improvement over Bump Stick cams. As far as my original question concerning having control over the DOD, I was considering calling a couple of the "custom tune " shops to see if they have started tuning the new burbs, Yukons, and full size pick-ups with DOD. Anyone have a recommendation on a reputable shop?? Thanks, PHIL

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