davidrcaldwell

I recently purchased a 2007 Tahoe LTZ. It's in excellent condition and under 48,000 miles. After a couple of weeks of driving, our in-town mileage was coming in at about 11 MPG in town and 15 MPG on the highway, a good bit lower than the 15 and 20 advertised. We have driven extremely conservatively, keeping the engine from going much over 2,000 RMP's, etc. Granny would be proud. Upon complaining to the salesman, he indicated this was very poor and to get it into the service dept. The service dept. determined that since there were no error/warning lights on, there was nothing wrong with the vehicle. They claim to have done a diagnostic check to be sure that all sensor input is correct to the computer, etc. They then spent no small amount of time convincing me that the heavy-duty towing package with it's 3.73 rear-end and transmission cooler combined with the 20" tires puts this mileage right where it should be.

I'm wondering if anyone is having the same experience or if I should push back?

Damien0869

Hi David, I must admit I was also in shock when I first got my 07 Hoe. I traded my 03 SLT Kon for the 07 Hoe and man, I was almost in bankruptcy, after the 1st month with the amount of gas the Hoe was drinking. I could never get it to where the 03 Kon was in mileage, not even close and this all with DOD V-4 crap.

So, I resorted to getting a new Cortex programmer from Superchips. I had a Gen I programmer for the KON but couldn't use it on the new Hoe.

As a result of a new programmer, I don't complain at all. I get 9L/100 hwy and city 11-12L City, better than factory specs and that is with driving hard and soft. To put it simply, I could not keep this vehicle without a programmer.

My V-4 DOD works way better and thus much more efficient, if I can use that word efficient in speaking about an SUV.

Try some research and discover a programmer that best suits you and your needs friend.

Damien

davidrcaldwell

Damien0869 - Thanks for the quick reply. Forgive me, but some of your abbreviations are not quite clicking for me, and I'm not sure how to translate Canadian gas consumption specs. Could you clarify what a "Kon" is? Also, a "V-4 DOD?" I'm also not sure what "9L/100 hwy" means, but I think that "11-12L" city means that you're getting 11-12 litre's per mile? Then again, that seems extremely low, so I think I'm missing something.

If I get a programmer, like the Cortex one you suggest, does it come pre-loaded with better specs? Do I have to guess? What do I change? Do you know if this will void a warranty? Can I also use this to see what data is being reported to the computer, to see if the sensors are sending correct data? (I had an old Mercury Cougar that suddenly had mileage issue and it turned out a sensor was reporting that the car was at 8,500 feet of altitude, thus dumping gas in by the bucket.)

Thanks a ton!

ousig2408

V4 DOD = the displacement on demand that our engines can go into (4 cylinder mode when under a light load). toggle your DIC to show instant MPG and it will show if you are in V8 or V4 mode. ours goes into V4 mode quite a bit on the highway when on flat ground
we have a 2wd with the 3.42 rear end. all city driving we get 14 - 15mpg and all highway with around 60-65mph we get 20+ but if I cruse at 70mph or more it goes down to around 18 or 19mpg. I have seen as low at 12.9mpg with 100% city/stop and go driving with using the remote start to cool it off early. it all really depends on driving style and terrain - it takes a lot of power to get these things moving from a stop.

is your Tahoe 4x4 also? if so then I would expect similar mileage that you are reporting - may

davidrcaldwell

May - Thank you for the definition. Yes, I have used that view on the DIC and, in my opinion, my Tahoe doesn't go there often enough. In fact, it seems to go to V4 mode only when I have no throttle engaged, ie, coasting. It seems like when not towing, the V4 mode could be used much more effectively. Sounds like that is what Damien has accomplished.

Yes, mine is a 4x4. As far as I can tell, it pretty much has every available option except the on-board navigation and backup camera. I love the vehicle. It's joyous to drive. The gas is hurting me, but mostly, it seems like with all of the advancements touted, it should do much better. I had a 1970 Blazer, 4x4, with 35" tires and a Holley double-pumper carb. on a 350 cu engine that was getting close to this mileage.

ousig2408

search this site or google blackbear tune. that guy does custom tunes for these trucks and I bet he can adjust a few things to help you on the gas mileage front.

yes your Blazer may have gotten similar mileage but it did not weigh 6000+ lbs and have all the confort and safety of these trucks...
my boss had an 08 Surburban that was 4x4 and he reported about the same mileage you stated.
regarding the V4 mode I can keep ours in it around town if I cruse around at 40mph or on the highway quite a bit just play with it for a while and you may be able to adjust your driving to keep it in V4 more. but yes if you push the gas much at all it jumps right into V8 mode. with your 4x4 and towing 3.73 rear end well there is not much you can do. you are handicaped quite a bit from the get go

Damien0869

Hi David, sorry about the abbreviations, Kon = Yukon; and Hoe= well Tahoe.

As for the mileage, forgive me, I am Canadian and we are Metric. I am not sure on the equivalent, all I know it's better than stock; and my wallet/bank account reflects that.
I should actually switch the DIC over and see what it would be in imperial. I am being truly honest with you I really have no further complaints about the fuel, it has been awesome getting better fuel mileage. The V-4 DOD does in fact seem to work quite a bit better and more frequent than stock, that is for certain. The transition from V-8 to V-4 is a lot better no growl and grown like stock.

As for the programmer, don't get me wrong, I don't want to advertise for a product, just speaking that my experience has seriously increased my fuel mileage as well as performance; which ever you choose to buy and set up on your vehicle has to be what is best for you and your wallet.

I am not sure in the United Stated as far as warranties are concerned, but here in Canada, we cannot be denied warranty claims or service as a result of after market programmers (which is good because, I don't have to remove my tune every time I go to the Dealership). If they are going to flash my pcm(on board computer) they ask me to remove my programming first.

Also there is a limited warranty with the superchips. It does come pre-programmed for your specific vehicle and allows you many changes.

Along with that yes, you may read/log in real-time almost everything related to sensors engine management, transmission etc. It will even record a snap shot for transfer to a computer.

I hope I have helped and not confused you even more.

DAMien

73shark

davidrcaldwell: Welcome to the forum.

My 2007 got 11-13 in town and 17-20 on the road. Had 4X4 and 3.73 gears. Interestingly enuf, the guys w/ 4.10 gears were reporting better mpg. Something to do w/ putting the engine in its sweet spot per a guy at GM. Had a Superchips before the Cortex model and tried both the economy tune and the performance tune. Neither improved mpg but the perf. tune did seem to give it a little more grunt but req'd premium and that was back when that was over $4/gal. Sold the Superchips.

Oh yeah, if you have a powertrain problem and the dealer finds a program in the ECM, he could deny warranty. But it's easy to put the OEM tune back in. I've been told that if they really dig into it, they can tell it's had a program due to some artifacts left behind. STSqrl might be able to weigh in on that.

Check out Blackbear.

My 2010 gets slightly better in town which I attribute to the 6-spd.

MDTAHOE

My 2007 gets between 11.5-12.9 always

SabrToothSqrl

Due to my factory 60,000 / 5 year bumper to bumper, I have not modified my Tahoe at ALL. (LED tail lights)...

I have the 6 speed, which is why I got the '09 vs a '08...

11-13 city.

17 combined

19 highway

15 towing 2 jet skis.

My '95 Tahoe only ever got 12.5 if I babied it everywhere. And that was 150HP new...