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Car Forum / Chevrolet / Chevrolet Trucks / March 2008GMC Yukon V8/V4 mileage
I recently noticed something on my 07 Yukon. When you're accelerating or climbing even the mildest grade it's always in V-8 mode. When coasting it switches to V-4 mode. So far, so good, just like the manual says. When you stop and idle, which happens to be the time you need the least power, it switches back to V-8 mode? Does that make sense? Is there any way to reprogram the computer to force the engine into V-4 mode more often. With the price of gas, I would gladly give back a bunch of HP for more MPG. Ever notice when you hit the cruise control's resume button it just about floors the gas pedal to reach the set speed? What were they thinking? Is there any way to reprogram that problem? John >I recently noticed something on my 07 Yukon. When you're accelerating > or climbing even the mildest grade it's always in V-8 mode. When [quoted text clipped - 10 lines] > about floors the gas pedal to reach the set speed? What were they > thinking? Is there any way to reprogram that problem? You buy a new 6000 Lb SUV that likely cost over $45,000 new and you're worried about this kind of nickel and dime mileage stuff? It makes sense to switch back to V8 mode when stopped and idling since you will be accelerating from a dead stop and need full engine torque to move the vehicle efficiently. The cruise control is designed to maintain vehicle speed. If you alllow speed to drop a considerable amount the vehicle will accelerate reasonably quickly to reach programmed speed. Taking too long by accelerating at the slowest possible rate is not efficient The "program" to not have it do that is re-engage the cruise right away or use your right foot to bring it up to cruise speed at the slowish pace you think is proper. You can't reprogram the PCM to engage cyclinder deactivation at higher loads. Even if you could, it wouldn't save fuel as it would lug the engine and would result in sluggish, non-seamless transition of periods of reduced power to full power. > You buy a new 6000 Lb SUV that likely cost over $45,000 new and you're worried about this kind of nickel and dime >mileage stuff? At $3.25, it's no longer nickel and dime. Not by a long shot. Is gas still $1.09 a gallon where you live? >It makes sense to switch back to V8 mode when stopped and idling since you will be accelerating from a dead stop and >need full engine torque to move the vehicle efficiently. Switching between V4 and V8 is seemless at speed. Why would it not be the same from a standstill. Wake up. The days of treating a red light like an NHRA tree are over. I don't need neck snapping acceleration. I gave that up at 19. >If you alllow speed to drop a considerable amount the vehicle will accelerate reasonably quickly to reach programmed >speed. Taking too long by accelerating at the slowest possible rate is not efficient Did you really say "Taking too long by accelerating at the slowest possible rate is not efficient" ? At least now I know not to take any of your posts seriously. > Even if you could, it wouldn't save fuel as it would lug the engine and would result in sluggish, non-seamless transition of > periods of reduced power to full power. I'm pretty sure if you didn't put the pedal to the floor evry time, it would save gas and not lug the engine. I don't want to see the engine in V4 mode because of a barely perceptable incline that doesn't really need double the HP. As I stated in my original post, I'm ok with losing some power. According to your logic, buying a car with the biggest engine available will save gas because it woun't lug the engine as often. Explain that. By the way, if you paid $45K, you got ripped off. John >> You buy a new 6000 Lb SUV that likely cost over $45,000 new and you're >> worried about this kind of nickel and dime >mileage stuff? > > At $3.25, it's no longer nickel and dime. Not by a long shot. Is gas > still $1.09 a gallon where you live? How much was it when you bought the unit? $3.00 per gallon? >>It makes sense to switch back to V8 mode when stopped and idling since you >>will be accelerating from a dead stop and >need full engine torque to move [quoted text clipped - 4 lines] > like an NHRA tree are over. I don't need neck snapping acceleration. I > gave that up at 19. Did I say you need to floor it from a stop? Apparently your reading skills are minimal. You want the vehicle to accelerate from a stop with 4 cylinders deactivated? Cylinder deactivation feel would not be "seemless" ,as you put it, from a halt. >>If you alllow speed to drop a considerable amount the vehicle will >>accelerate reasonably quickly to reach programmed >speed. Taking too long [quoted text clipped - 3 lines] > possible rate is not efficient" ? At least now I know not to take any > of your posts seriously. Efficient in terms of maintaining highway speeds. And now I know not to take any of your posts seriously. >> Even if you could, it wouldn't save fuel as it would lug the engine and >> would result in sluggish, non-seamless transition of > periods of reduced [quoted text clipped - 7 lines] > biggest engine available will save gas because it woun't lug the > engine as often. Explain that. Again, you reading skills are poor. It nowhere said putting your foot to the floor. As for the rest posted there, it's pointless to reply. > By the way, if you paid $45K, you got ripped off. Well, I guess that depends on the model and options doesn't it? Everyone in the world has your exact model, trim and option level, right? Your complete ignorance of the product line's MSRP for 2007 speaks volumes. The MSRP ranged from 37K for the to over 50K for the Denali XL loaded up. > John >> You buy a new 6000 Lb SUV that likely cost over $45,000 new and you're >> worried about this kind of nickel and dime >mileage stuff? > > At $3.25, it's no longer nickel and dime. Not by a long shot. Is gas > still $1.09 a gallon where you live? WOW, that cheap, I'm lucky right now to find it as low as $3.55 for plain old unleaded. I'm guessing this Summer that Gas will get up into $4.00, and be like that full time next year. It's already over $4 for Premium curently. Filled my tank in my 03 Chevy 1500 was $70. Luckly I have a short commut about 10-15 minutes depending on the lights. Need to finish getting my Harley cleaned up and a few things added and ride it a lot more. Much better milage. In article <5716c6ba-2203-49f6-b322-637ed95d2849@s8g2000prg.googlegroups.com>, > > You buy a new 6000 Lb SUV that likely cost over $45,000 new and you're > > worried about this kind of nickel and dime >mileage stuff? > > At $3.25, it's no longer nickel and dime. Not by a long shot. Is gas > still $1.09 a gallon where you live? Was gas $1.09 a gallon when you bought the truck? > >It makes sense to switch back to V8 mode when stopped and idling since you > >will be accelerating from a dead stop and >need full engine torque to move > >the vehicle efficiently. > > Switching between V4 and V8 is seemless at speed. At speed. > Why would it not be > the same from a standstill. Because idling an 8 cylinder engine in 4 cylinder mode would shake, rattle and roll. There are also emissions related issues with the disabled cylinders cooling off too much at idle. > Wake up. The days of treating a red light > like an NHRA tree are over. I don't need neck snapping acceleration. I > gave that up at 19. It's got nothing to do with neck snapping acceleration, it's got to do with noise, vibration and harshness. GM tried this once before, it was a monumental disaster. This time they very much decided to avoid a repeat. GM doesn't much impress me, but the job they did implementing their displacement on demand system impresses me. Or, maybe it's because they (and Chrysler) sourced the hardware from Eaton. > >If you alllow speed to drop a considerable amount the vehicle will > >accelerate reasonably quickly to reach programmed >speed. Taking too long by [quoted text clipped - 3 lines] > possible rate is not efficient" ? At least now I know not to take any > of your posts seriously. You'd take him seriously if you understood volumetric efficiency and how it relates to internal combustion engines. > > Even if you could, it wouldn't save fuel as it would lug the engine and > > would result in sluggish, non-seamless transition of > periods of reduced > > power to full power. > > I'm pretty sure if you didn't put the pedal to the floor evry time, Funny... When that engine switches from 8 cylinder mode to 4 cylinder mode, one of the things that happens simultaneously with disabling the valve lifters/injectors/spark is the throttle is opened a very large amount. > it would save gas and not lug the engine. I don't want to see the engine > in V4 mode because of a barely perceptable incline And it probably doesn't. The engine is programmed to not stay in reduced displacement mode for an infinite amount of time, the cylinders are switched back on after a not very long interval (I'd have to check my notes for the exact duration) for reasons I've listed above. > that doesn't really > need double the HP. As I stated in my original post, I'm ok with > losing some power. According to your logic, buying a car with the > biggest engine available will save gas because it woun't lug the > engine as often. Explain that. True to a point, like most things, there's a window where peak can be optimized. > I recently noticed something on my 07 Yukon. When you're accelerating > or climbing even the mildest grade it's always in V-8 mode. When > coasting it switches to V-4 mode. So far, so good, just like the > manual says. When you stop and idle, which happens to be the time you > need the least power, it switches back to V-8 mode? Does that make > sense? No, it doesn't. I would have assumed it would be in I4 mode at idle. Otherwise there'd be almost no reason to have the cutoff. There is absolutely no reason to have 4 cylinders doing nothing at idle. > Is there any way to reprogram the computer to force the engine into > V-4 mode more often. With the price of gas, I would gladly give back a > bunch of HP for more MPG. Talk to Ex-Governor Bush. He's the one who's raised the gas prices by lowering the value of the dollar. I wonder what President Bush thinks of his son these days? > Ever notice when you hit the cruise control's resume button it just > about floors the gas pedal to reach the set speed? What were they > thinking? Is there any way to reprogram that problem? That's typical of many cruise control computers. I rarely use cruise but when I have, I've seen this. By the way - you have large truck. It is safe and will carry a ton of sh.t. If you wanted gas mileage you could have bought a subcompact Prius or Camry and taken your life into your hands.  Signaturewww.perfectreign.com || www.filesite.org powered by the lizard: www.opensuse.org > Talk to Ex-Governor Bush. He's the one who's raised the gas prices by > lowering the value of the dollar. > > I wonder what President Bush thinks of his son these days? There is a glut of US dollars on the world economy because we spend them every where but here, and there is nothing here they want over there because we dont manufacture jack sh.t anymore. and now its starting to bite us in the a.s. Whitelightning >>Talk to Ex-Governor Bush. He's the one who's raised the gas prices by >>lowering the value of the dollar. [quoted text clipped - 7 lines] > > Whitelightning And not to mention that "The Shrub" is a moron. Has to be the worst President this country has ever had. Not only a liar too but he thinks he's above the law and doesn't need to follow the constitution. Bob >>>Talk to Ex-Governor Bush. He's the one who's raised the gas prices by >>>lowering the value of the dollar. [quoted text clipped - 13 lines] > > Bob Nope, not true at all. First off, Jimmy Carter had to be about the worse president ever! Bill Clinton wasn't much better. You do know the terrorist have been at war with the US long before BUSH was ever president. Bush wasn't president at the first world trade center bombing. Or many of the others. US just sat on it's a.s and let it go on and on and allowed the problem to just get worse.. Buying cheap crap from CHINA is sending all our money there these days. Before that it was Japan. Can't drill for oil Domestically, means buying it from Terrorist supporting countries. The US needed to go into Iraq! I keep hearing that the only reason was Weapons of Mass Destructions, but Bush laid out many different reasons, that just one of them. Bushed did screw up disbanding the Army, but the current surge is now working. The US can't just leave. The US hasn't just left other countries either over the years. If the US leaves, the country will be bloodbath with IRAN taking over. You think Israel will put up with that? Not likely. The whole middle east will be a screw-up, and Gas prices will skyrocket. You want to be paying $10 a gallon? What happens when the US leaves Iraq besides the bloodbath over there and high gas prices, well now even more people are P.O.ed at the US and so they come here and start Bombing everyone including YOU because they could care less about YOU. Your a Infidel, there's only DEATH or slavery for you, and a quick death would be better! Bush hasn't LIED. If that's true, then most of Congress LIED, along with many other countries that said the same things BUSH HAS! You like the other nuts can keep blaming BUSH, and the US, everyone but the freeken Terrorists. It's pretty simple. They stop the mass Murdering over there, we the U.S. pretty much leave the country. What a waste of 4,000+ U.S. lives to just leave and let the country go to hell. Same B.S. going on like Vietnam. U.S. could have WON, instead of the stalemate it's been at all these years, buy thanks to the B.S. Protesters here at home. Man if the same thing happened for WWII, I wonder if today we would all be speaking German. But you go on rampage and keep blaming BUSH!!! I bet you LOVE the Protesters at the Funerals, and the Fake Blood being thrown in churches. You people make me sick! >>>> Talk to Ex-Governor Bush. He's the one who's raised the gas prices by >>>> lowering the value of the dollar. [quoted text clipped - 54 lines] > Funerals, and the Fake Blood being thrown in churches. You people make > me sick! And you people with blinders on make me sick. The Shrub is an idiot and has screwed up this country royally. After 9/11 we had the support of almost the whole world. The Shrub sure screwed that up in no time. Neither you nor any other Shrub fan boy will change the way I feel about it. It's time for a major change in this country and it will come as soon as the Shrub and his crooked administration leave office. It can't happen soon enough. And may God bless our men and women in the armed forces and their families that are suffering because of The Shrub's lies, illegal activities, and arrogance. Not to mention his stupidity. Bob >>>>> Talk to Ex-Governor Bush. He's the one who's raised the gas prices by >>>>> lowering the value of the dollar. [quoted text clipped - 65 lines] > > Bob Well you have the blinders on as everyone else in the world said the same thing as BUSH. Everyone was happy at first, and then people started to die, and everyone else changed their tune but BUSH! I'm sure though that you blame the US for 9/11 also am I right? If BUSH lied, then most of congress and the senate lied, along with the rest of the world. As for Illegal Actives, what would those be? Why don't you name them! I can almost see Smoke coming out of your ears your on such a Anti-BUSH trip. I almost hope a Democrats wins, and Yanks all the troops out of the country and then we can watch the bloody hell IRAQ will really turn into which will spread, and the US will continue to get blamed on for that. With even more people angry with the US, the flight will be coming HERE, which will be people blowing themselves up left and right. Who knows, maybe one of them Car bombs will go off around you or better yet your family and then I bet you'll change your tune. You don't like it now, just wait and see how bad it could end up getting if we then have to go back!!! Oh, and I know I can't change a nuts mind so I'm not even going to try. In fact since this is a Chevy Forum, I'll just start blocking this topic as it's just a waste of my time. Goodbye nut job. >> And you people with blinders on make me sick. The Shrub is an idiot >> and has screwed up this country royally. After 9/11 we had the support [quoted text clipped - 27 lines] > not even going to try. In fact since this is a Chevy Forum, I'll just > start blocking this topic as it's just a waste of my time. Goodbye nut job. Blah blah blah. Plonk >>>>> Talk to Ex-Governor Bush. He's the one who's raised the gas prices by >>>>> lowering the value of the dollar. [quoted text clipped - 65 lines] > > Bob Bob, the flaw in your logic is astounding. You accuse someone else of being narrow minded, then admit that no one will change your mind. Who has the blinders on? Before you accuse me of mistating your position, consider this: anyone whom you agree with today, but changes there mind tomorrow, thereby becoming a "Shrub fan boy," is someone you'll disagree with tomorrow, therefore they won't change how you feel. Logically, no one can change how you feel. That's not what I call open minded. > Bob, the flaw in your logic is astounding. You accuse someone else of > being narrow minded, then admit that no one will change your mind. Who [quoted text clipped - 5 lines] > therefore they won't change how you feel. Logically, no one can change > how you feel. That's not what I call open minded. What is open minded? If I say putting your hand in fire will result in a burn, and no one will convince me otherwise, does that mean I have a closed mind? Thats how I see your arguement right now on being open minded. This is one of thsoe things, the shape of the current thread that is, that has two sides that are not going to budge. Whitelightning >> Before you accuse me of mistating your position, consider this: anyone >> whom you agree with today, but changes there mind tomorrow, thereby [quoted text clipped - 9 lines] > This is one of thsoe things, the shape of the current thread that is, that > has two sides that are not going to budge. I tend to agree. Being a discussion about trucks, we can digress a bit and go off on gas prices, but do degenerate into a name calling fest over the politicians in charge just loses any value. I suppose we'd be better off wondering why some of us are driving e-85 trucks and are unable to actually purchase e-85 due to a complete lack of stations within a 100-mile radius. (California currently has *two* entire e-85 stations available to the public.) http://e85vehicles.com/e85-california.htm http://www.eere.energy.gov/afdc/progs/ind_state.php/CA/E85 Hey, one just opened up in Los Angeles over on the uber-crowded westside slums near Beverly Hills and Brentwood. Looks like it is across the freeway from UCLA. Let's see - if I leave now, I could probably make the 30.2 mile trip from work in... let's see.... two hours depending on traffic. (According to google maps.) Signaturewww.perfectreign.com || www.filesite.org powered by the lizard: www.opensuse.org >> Bob, the flaw in your logic is astounding. You accuse someone else of >> being narrow minded, then admit that no one will change your mind. Who [quoted text clipped - 15 lines] > > Whitelightning Using your example, I define open minded as saying "I am very doubtful that you can convince me that putting my hand in a fire will not result in a burn, but I will listen to your argument, then decided to accept or reject your argument." Suppose you're sitting around a campfire and someone puts a fire retardant jell on their hand and sticks it in the fire for 10 seconds, then removes it with no burns to his hand. Will you reject his demonstration just because no one will convince you otherwise? I know it's a bit of a stretch, but I'm working within your example. My point is that definite statements like "you won't change my mind" indicate someone unwilling to listen. We will never get anywhere if people are not willing to listen, or worse prevent others from talking. |
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