14 tahoe 4x4 poor fuel mileage help

dirtymax6610 said:

I bet i could to by dropping that 2.9 whipple i have on the shelf on it....lol

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You know you wanna sell that Whipple to me
Does she have the 3.42 gears in it or 3.73s?

First off, the larger rims & tires require more energy to get them up to speed, like city driving. The part that was left out is milage that high can only be pulled off with highway driving.

The motor and trans are new and tight. Give it a little time to break in. Check those fuel trims, o2 sensors & cats.

Only use OEM/ac Delco o2 sensors from known, trusted retailers to avoid the counterfeit overseas parts.

Congrats on the major refresh of the truck. Just take the diagnostics a bit at a time. If not done yet consider an engine trans tune from black bear

dirtymax6610 said:

Now to the point of all of this. This was supposed to be a good daily driver for the wife. When i was picking out the cam and other stuff from Texas speed i talked with there tech support on picking out my parts. There guy said they have done many of these builds with the stage 2 truck cam and they average around 23 miles per gallon. Since this build have put about 7 thousand miles on it and the best average fuel mileage is about 12.5 to the gallon.

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I'm not sure what the spec's are for that cam but from experience a cam, tune and dod delete will get you worst milage than before. I have never heard anyone get 23 mpg on a 6spd tranny. My stock yukon on 32" tires gets 13mpgs. So 12.5 with your set up is about the best you are going to get.

Could you be using high alcohol content fuel? That would cause a drop in mileage.

houstontaylor said:

Could you be using high alcohol content fuel? That would cause a drop in mileage.

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A recent transition from E10 to E15 could have been inflicted upon you without your knowledge.

so I saw a suv on tires yesterday and it made me think. is your speedo calabrated for the larger tires? most don't, simple with hp tuners. my yukon with stock tires read 2mph off, so I adjusted it.


if not that effects you're odometer reading too.

The best I recently got was 19.5 MPG, which was all highway driving from Riverside County to just north of Vegas. Very impressed for a stock Tahoe