Gas mileage questions...

lt1transam · September 26, 2005

I was wondering what everyone was getting. I am fixing to do a few things to see about helping the 5.3 out some. I have always has K&N filters and genII FIPK's and noticed mpg improvments from both. The latter being the greater improvment. At present we are lucky to see 14 mpg from it. I am thinking the GenII and an electric fan will make a descent difference. Feel free to drop some numbers in here and compare before and afters of adding mods. Thanks!

Chad H · September 26, 2005

I would stick with the stock filter. Eletric fans and a westers tune would yield 4 mpg+ , I would think.

Wingnut · September 27, 2005

A lighter right foot is the best improvement.

Followed closely by a custom tune. (But this costs $$, and will take quite some time to save what you spent on it.)

FIPK's have never gained me anything.

bobcat5544 · September 27, 2005

Look at the 8th diget in the vin is it a (t) or a (z)

BlueTahoe · September 28, 2005

I would say a custom tune and E-fans also. I was getting about 16-17 highway when my tahoe was new. I went to larger tires 285/75/16 and it dropped to about 14-15. I have done a cat-back exhaust, Cold air intake, wester's tune, and electric fans. I didn't see much difference with the exhaust or intake as far as MPG but they sure sound good. Wester's tune was by far the best MPG increase. E-fans a close second. I am getting about 16-17 mpg in 50/50 city highway driving now. I havn't made a trip since both fans and the tune but I would guess I could see 19 on the highway. I may go back to smaller tires next summer and I would expect 20+ on the highway if I get rid of the big tires.

Oh and the truck flat out hauls now compared to how it ran before the tune. Westers is hands down the best performance mod I have ever done for the money.

Not sure about why they are asking about the vin but mine is a vin Z if anyone was wondering.

AggieGunslinger · September 29, 2005

I am kind of in the same boat. I have had my truck 1 year today and over 33k I am at 17.9 mpg, not bad but still looking to do better.

lt1transam · October 26, 2005

The Tahoe has 43,000 miles on it, any "regular maintenance" stuff that would help? And where the heck is the PCV valve on the 5.3? As far as I know everything is original on it.

trever1t · October 26, 2005

I just went to Yosemite and back, around 700 miles with all the up and down and around Yosemite and averaged 18.5 MPG. (according to DICS)I was thinking this was kind of low but ok, i guess it's pretty good!

Running Mobil 1 if oil can make a difference and premium fuel with Hypertech III. Will soon be installing Wester's.

05blackz71 · October 26, 2005

Look at the 8th diget in the vin is it a (t) or a (z)

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What exactly does that 8th digit decode???

Trav_13 · June 8, 2006

The eight digit of the VIN should either be a "T" or a "Z"....probably what they are referring to is whether or not your motor will run the E85 Flex Fuel. Ethanol is supposed to burn cleaner, and be a little cheaper, however I don't believe you get quite as many MPG with it as you do with regular 87-89 Octane Fuel. Either way if its a "T" its a non-flex fuel and if its a "Z" its a flex fuel.

Look at the 8th diget in the vin is it a (t) or a (z)

<{POST_SNAPBACK}>

What exactly does that 8th digit decode???

<{POST_SNAPBACK}>

C & A s Dad · June 9, 2006

LT1 Trans Am, the PCV valve is on the left (drivers side) valve cover right at the firewall.

If you replace it, be sure you use the fixed orfice style if your truck came with this type from the factory. The Fixed Ofice has a small hole in the bottom and no valving inside.