Gas Mileage on my 260z

[B00STDZ]

Well alot of you know my car is running now. With it running I've been driving it every once in awhile. What I have noticed is that this car loves to stop at the gas station. I recently reset the odo on a full tank just curiously seeing what my gas mileage would be. So then I drive it around over the next couple of days until the odo reads 31, 93 oct gas was cheap yesterday so i was like why not.

 

I fill up my car and guess how many gallons it takes?

3.7!!!

 

Now if you do the math 31/3.7=8.37.

 

So basically my car is getting 8.4 miles to the gallon. Rofl.

 

Is this normal? I don't believe my car is running rich because when i accelerate hard i don't see any black smoke. I see very very slight black smoke when i start the car but thats about all.

 

 

Also what I've noticed is when my car only has a gallon or 2 in the tank it sputters on the top end. I dont find the guage very accurate when it gets toward E so this is kinda helpful so I know when to refuel. Kinda weird at first though. When I was low on gas I would always think something wasnt right but really it was just the gas being low.

 

 

*EDIT*

Also wanted to mention i have a 3.36 LSD r200, 630cc injectors, walbro gsl392 and 82 280zx non turbo 5 speed

Edited August 22, 2010 by B00STDZ

[SHO-Z]

As for the sputtering with 2 gallons in the tank, your gas lines are switched at the tank. Had this on my z after I dropped the tank years ago and connected them wrong. Your z should get in the mid 20s if it is tuned properly.

[DuoWing]

I could be wrong, but I thought I've also heard that when using the older pre-fuel injection Z tanks something about it doesn't pressurize right or you can have issues in higher RPMs when trying to use it with fuel injection?

Edited August 22, 2010 by DuoWing

[datsun723]

I get like 15 in town and maybe 20 on the freeway. Stock L28 with r180 (3.36?). I need to get the fuel injection flushed

[Challenger]

Might want to mention what your running for fuel management and your tune. Arent you using haltech? How many psi you running? How do you drive it? Arent 630cc injectors way to big? Do you have a WB02?

Edited August 23, 2010 by Challenger

[randy 77zt]

check the ignition advance curve and get a wide band o2

[B00STDZ]

I do have a wideband o2. Running 12 psi. Using standalone haltech plat sport 2000.

 

Well I drive the car... rather hard .

[sticky280zx]

just asking but wouldnt the lower rear use more than say a 3.5 or 3.7/staying in boost longer/using more fuel, also you are using the 5spd on a car that wasnt before? So you might not be getting the right mph/odo because of the swap? those are the things standing out making me think that it would be that low, and obviously if the car is turned on..>RAPED...then turned off everytime then its prolly not gonna get great milage, the heavier your foot the worse it gets. I used to drive a chevy turbo diesel, lifted, etc truck and if i drove it nice its get 15-20 and if i stomped it around town itd get 8...so yea it could just be the heavy foot.

[goodoldjam]

I do have a wideband o2. Running 12 psi. Using standalone haltech plat sport 2000.

 

Well I drive the car... rather hard .

Well if you drive it hard , then what's the question? Drive it easy and see what you can do, I think I could drive my car around town and not see any positive pressure. If I floored it and kept it in it's power range I would hope to get 9mpg with fuel almost pouring out of my exhaust pipe.

Edited August 25, 2010 by goodoldjam

[Tony D]

I could get 17mpg, or 5...all dependent on my right foot.

 

If you see black smoke, you are at 10.5 or richer on a non-catalyzed L-Engine (pig rich).