Gas Mileage?

[Kennys91TransAm]

I have a 91 Firebird its a 305 TBI and it has a 15.5 gallon gas tank.I'm only getting 190 miles on a tank of gas.given I do live in Tennessee and theres a lot of curves and stop and go driveing I think I should get a lil better than12.25 miles a gallon. I got it tuned up because I thought that would help, but i've seen no improvement. I also tried useing 93octane but that made no diffrence eithere. I was wondering what kind of gas mileage the rest of you were getting and if theres anything I could do to improve mine?

[MdFormula350]

i am around 200 during the summer before the gauge is close to the yellow. during the winter it has gone down alittle.

[TafEel]

gas milage can be drastically affected by the way you drive. if you granny drive you can improve your economy but if you drive like the rest of us hard accells, speeding, hard braking, accelerating uphill not coasting downhill all kill feul economy.

[1BadL98]

my L98 averages 22 MPG if that tells you anything. More if I baby it.


Is your O2 sensor working properly? How about your coil/cap/rotor? Are your spark plugs indicative of running rich?

[Corey]

First off you shouldn't be calculating your mileage by the capacity of your tank, you should be reading the gas pump when you fill it up, which in reality is probably around 12-13 gallons.

Even that still leaves you a little on the low side though.

I got around 17-18 mpg before the gear swap on my car. Now it is around 15-16. Straight highway mileage used to be about 23, now about 20.

Did you get a new oxygen sensor with the tune-up? That may help. Any "check engine" light/computer problems? That will kill gas mileage like a mofo.

[Kennys91TransAm]

Yes I do accelerate fastly and break hard. It has had a tune up and a new distribuator cap and that other thing that I cant remember done. New plugs plug wires and timeing. Maybey im crazy I was just wanting to know if the rest of you were getting horible gas mileage to or if I was the only one. So I guess I'm just SOL and might as well get used to it right?

[Kennys91TransAm]

Well im not sure why mabey the tune up fianally started working or something but its been getting better gas mileage it may be do the fact I am driving slower since I was with my friend when we flipped and totaled his car. The last two times I've got 16miles a gallon and then the last one it got 21 miles a gallon so thats not to bad if it stays like that.

[karlseus]

I use to get between 11 and 12 MPG with my carburated 305. First off a carburator sucks anyway. But mine was close to trash. Swapped it out with a TPI setup and now I get 15-16 MPG with a 350 on the same car. And AS most of you I am a hard accel driver. It would be more But I have lower gears in the back then stock.

[Kennys91TransAm]

how much did it cost you to switch to TPI??? and would it be better to just get a performance Carb?

[karlseus]

This is a debate between hotrodders all over. Carb versus fuel injection. I think Tpi is the way to go. Carbs do not atomize the fuel as well as injectors do. Thus you can get more Torque out of the engine from a Tpi system. And definetaly fuel economy. I purchased most everything from e-bay.

These are what I payed for the components. Prices do vary.

$200 for Intake setup with everything on it(Except MAT). Includeing injectors for 305(19lbs). e-bay
$100 for 350(22lbs) injectors. e-bay
-$70 sold 19lb injectors. e-bay
$100 for 2 wiring harnesses. Came with all sensors and a computer. e-bay
-$100 sold 1 wiring harness(all wires marked) e-bay.
$35 for dual fan setup e-bay
$90 for 60psi in tank fuel pump. e-bay
$35 for intank sending unit to mount fuel pump e-bay
-$35 got refund for sending unit because it was clogged e-bay.
$90 for MAF sensor e-bay.
$35 for dual air cleaner. e-bay
$50 various components(IE fuel lines, heater hoses). Autozone
$20 for Dist cover e-bay.
$60 for MAT
$35 350 programmed chip for computer TBI parts from e-bay.

[karlseus]

I spent around $600 for the complete TPI installation. all said and done. I did all the work myself with a couple of electrical problems that were a little confuseing but not to bad.