Jason Dove

Okay let's see now...

200km per 50 litres = 4km/litre

4km x 1km / 1.6 miles = 2.5 miles

so we're at 2.5 miles / litre

2.5 miles / litre x approx 3.785 litres / gallon = about 9.46 miles per gallon.

That's with new everything (including motor, opti, wires etc) except EGR... so that's what I'm looking into next.

WhiteBeast

Actually i am not even getting 240 miles out of my tank. I am actually only going to be getting about 220 miles. I was estimating what it might be when the bar hits E.

Ok, here is my actuall problem. I was getting about 80 miles when the bar hit 3/4 tank full. I figured that if i got 80 miles every 1/4 of my tank then i would get around 300-320 miles out of my tank. Well now my gauge is on E and the mileage is 211. So what happened to the other 100 miles?

As soon as the gauge hit 3/4 of a tank it just dropped rapidly over time.

I actually think it was just under 1/4 this morning and it is now at Empty and this is only driving about 15 miles normal driving. So could something be wrong with my gauge?

Also does a low fuel light suppose to come on with our cars, because i havent seen one yet.

And how much gas does my gas tank suppose to hold?

Well i recently installed a new Cold air intake and replaced my plug wires and spark plugs. Based on my calculations i am seeing about 13mpg which is horrible! Hopefully there is just something wrong with my gauge.

jeffwood

i get about 260-270 average out of a tank with 93... i hate the GM gas gauge... it goes to half a tank around 200 miles then zooms down to e at from 200-260 miles

Stock Z

The problem is you only drive 15 miles a day.

During this time your car spends a good portion of the drive running in open loop, meaning the computer is not using the O2 sensors and specifically making your car run rather rich. I would bet if you let your car warm up before you drive to work/school and back home you would see an increase in MPG.


BTW, i drive about 10 miles a day with probably half of that in open loop and get an amazing 12 mpg. But with all highway driving I see 22-24 mpg.

WhiteBeast

Stock Z,
Thanks for the information. That makes a lot of sense. So how long should i normally let the engine warm up too before i drive it in the morning?

The only problem is that if i let it idle too long, then i would be burning even more gas letting it warm up into closed loop.

Thanks

NewbieWar

Well ur gauge is acting the way its supposed to, i just hit 3/4 today and i got 80 miles on the trip odometer, and i will probably get to about 120 by the half, about 150 on the 1/4 and about 180-190 if i run outa gas the sensors were just designed to be far from linear but u will get used to it, when it gets close to "E" fill up!

and no u dont have a fuel light... if the needle gets close to the E fill up

I belive it is a 16.7 gallon tank

u might check ur O2 sensors, perhaps u have a clogged cat (will occur if previous users did not use sufficent octane) u should always use 91 or more

check those 2 first and for most

fdxpilot

The gas gage is a problem in both 3rd and 4th gen F-bodies. The gage measure the level of gas, but due to space limitations, the tank is triangular in cross section, with the small end at the bottom, so the gage is not linear. Therefore, the 1st 1/4 tank is actually about 1/3 of the tank (in my case, about 100mi), the 2nd 1/4 is actually about a 1/4 (70mi for me), the 3rd is about 1/5 (40-50mi) and the last 1/4 is maybe an 1/8 (30mi). The tank allegedly holds 15.5 on my 94 and there is no low fuel lite. At E, I can get almost 15 gals in mine, at 1/4 remaining, I can get 12.5-13 gal. When I fill it to the shutoff, the needle is well above full mark. I try never to let it get below 1/4 tank, because I figure I only have 20-30 city miles left (usually 16-18 mpg). Of course, on the highway at steady 70-75, I can get 22-24 mpg, depending on temp and hills. 13 mpg around town is reasonable if you get on it a lot, but not if you're shifting at 2k and cruising at 1500.

NewbieWar

if i remember correctly ive put in about 16.2 galons in mine... so i know its not 15.5

ShelbyZ28

I get 16-17 MPG in pure city driving. I can manage just over 20 when I drive 90% highway and 10% city. I've never really ran a tank down on pure highway but I would hope for 25 or so.

Bryan

WhiteBeast

Well, first gear shifts about 2500 rpm and then i normally cruise about 1500 but i do punch it a few times a week.
Tomorow i am going to check my cat and hopefully i will find that it is clean (but hope it is clogged so i can replace it)

Anyway thanks for everyones imput. I guess i will just have to get used to a V8 engine.

dobe

w/ exhaust and cai etc my car got ~18mpg town and ~27mpg highway
now it gets ~15mpg town and ~23mpg highway

LT1ponykilla

My gas mileage sucks. On a full tank I get less than 200 miles. I have recently changed the 02's and it still sucks.

shoebox

Indeed, the listed capacity is 15.5 gallons. It probably does not include the filler neck.

1999 is when they changed to the 16.8 gallon tank.

NewbieWar

well how much does filler thing hold?

cause i know my first fill up i paid $33 and some odd sense while gas was 1.99

2QUIK6

Couple of things, if you're tank is empty, you will almost always put in more gas than what the tank is advertised to hold, maybe becuase its rated capacity is not brim full running out of the filler neck, or your local gas station is ripping you off by a gallon or two for every ten (not unheard of and the pump will almost never measure incorrectly in your favor).
The other thing mentioned about driving around town causes it to be in open loop...if the coolant is above the specified temp in the PCM, it will be in closed loop, so you are not driving around in open loop half the time, something is wrong if you are. It should normally take the engine running for about 3 minutes to reach closed loop operation. If your BLMs are normally above 128, then driving in open loop could actually save you gas.
The only time the PCM would go back to open loop is possibly during periods of excessive decelleration, coasting for a long time with the tps at 0%, or WOT. So unless your driving around town with your foot to the floor or totally off the pedal all of the time, then its in closed loop, which I know some of us do drive that way