Bad Gas Mileage [Merged 9-6]

[99GST]

I am still getting some pretty bad gas mileage.

I am only getting about 19.7 mpg with mostly city driving shifting at 4k.
I have already replaced my front O2 sensor and am looking to replace the fuel filter.

I have a 99gst with about 55k miles on it. Should my fuel filter already be bad?

What else should I check or change? I have NKG plugs and Accel wires are on the way.

Thanks,
Nathan

 

[Kash]

If he wants to sell it, pm me on aim at daniel391 or email [email protected] me b/c im interested once i can sell my esi.

 

[paranoidTSi]

I get crappy gas mileage in my TSi AWD, bad 2nd O2 Sensor...I get about 210-220 to the TANK!

Its horrible, but nothing to make me stop driving my beast.

 

[DSMSpyder99]

300-310 miles on a full tank with 75% highway and 25% city. I use to get worse but then i got my new plugs and wires and i gained about another 25 miles in a tank.

 

[WSU99GSX]

Damn I get about 200 miles to a tank, on my 99 GSX...that bad?

 

[2gGSX]

depends on how much gas you put in
i usually only get about 10 gal in

 

[RedTurboEclipse]

tell him to quit his whining.. and get use to it.. i get 150 miles per tank if im lucky..

 

[noz]

yupe same as everyone here, i get 200 miles per tank -average of 20mpg if my car sees WOT.

If i shift average 2k then ill get over 300 miles per tank easily, this is only possible if you can resist not stomping on the gas pedal every now and then just for the fawk of it.

just tell your bro to chill with the gas pedal. giving the car WOT just a couple times per tank will drop the mpg hella low unlike honda's where it makes little difference giving it WOT a couple times.

 

[NOAHSR10]

With crappy tuning and being high on RPMs (shifting at 5500) I usually get 210-220 from "F" to "E". But the tank usually lasts me about 270 I wouldn't trust the gauge, check how many gallons fills it next time you get gas... should be around 15.9

 

[WSU99GSX]

Yeah our gas gauges seem to go down fast, not very accurate...

 

[Davidle]

Originally posted by 10minutecar
Maybe you get such bad mileage because of all those AWD burnouts.

Hey, we have the same name: David

You know it! haha. J/K

Davids a tight name!

 

[GeneralChaos]

Originally posted by paranoidTSi
I get crappy gas mileage in my TSi AWD, bad 2nd O2 Sensor...I get about 210-220 to the TANK!

Its horrible, but nothing to make me stop driving my beast.

same here, bad 2nd o2 sensor when I got it, got 100 bucks off the car and have the o2 sensor just sitting here not put on because I found I have no wrenches! doh!

I usually drive like a granny, and cruise around 80 on the highway, and the milage isnt go great, but I love the car so pay to play!

 

[LightningGSX]

On the "E" mark with the low fuel light on, I have an average of 4 gallons left in the tank.2g fuel gauges read way lower than actual.BTW the average lifespan of a narrow band o2 sensor is around 40k miles, IIRC I've seen recommended replacement intervals(General Motors) as low as 28k.An occasional tank of leaded race fuel will reduce the lifespan even further.

 

[WSU99GSX]

So a 99 with only about 52k miles might need an o2 sensor already? Wow, both of them or just the one?

 

[10minutecar]

How can you tell if the 02 sensor is bad?

And how can you tell which one is bad?

I am getting him to order the Apex'i turbo timer with the 02 reading built in, would that tells us if his sensor is bad?

Is there a fix for the gas guage?

 

[AzhigherTSI]

I've got a TSI AWD with Automatic and I'm only getting 160-180 miles a tank.... Think it might be an o2 sensor? or is the auto just that bad? Granted it is mostly ALL street driving.

 

[Rice Over Wheat]

Ok, I've been having some really poor mileage...A full tank of 93 octane gives me about 180 miles or so.

I have the following built transmission from ATF. It was done this last November:

Banner Overhaul Kit
Rebuilt exchange torque converter high stall @ 2800 RPM
Solenoid assembly
Bearing kit for differential plus complete differential
Transmission fluid
Shift kit
2nd gear band

$2600 parts/labor

Just yesterday I picked up my car from Speed Injection...Garry Marsh (fastest FWD dsm in the world) tuned it with SAFC II...my car dyno'd 242 HP x 268 Torque. I'm running 15lbs of boost. The car is very fast, but like I said...the fuel efficiency sucks ass.

Is there any way to increase fuel efficiency without losing power? I think auto with all my upgrades is really killing my mileage.

ROW

 

[LightningGSX]

You can bench test them with a propane torch, I don't know the exact procedure or how accurate it is.If you monitor o2 voltage, As long as you have quick/sharp transitions(above and below .5 volts) in closed loop mode, and have relatively high voltages in open loop, I would assume it is functioning correctly.The post cat 02, should be relatively low voltage, with a smooth response, no sharp transitions..This is definately not a "rule of thumb", the o2 may be functioning correctly but, it could still be innaccurate.I usually just replace the primary one every 35k or so, they probably are capable of lasting a lot longer than this, but they are easy to break or contaminate.My 2g only has like 33k, and I already had to replace the primary one a few thousand miles ago(it was reading constant 0 volts).As far as the gas gauge, you could add a potentiometer or similar and drive untill you run out of gas to "calibrate" it(wouldn't recommend this, sometimes running a fuel pump dry will kill it).

AzhigherTSI,
Yeah Automatics get worse gas mileage period.

 

[transdude]

Originally posted by Rice Over Wheat
Ok, I've been having some really poor mileage...A full tank of 93 octane gives me about 180 miles or so.

I have the following built transmission from ATF. It was done this last November:

Banner Overhaul Kit
Rebuilt exchange torque converter high stall @ 2800 RPM
Solenoid assembly
Bearing kit for differential plus complete differential
Transmission fluid
Shift kit
2nd gear band

$2600 parts/labor

Just yesterday I picked up my car from Speed Injection...Garry Marsh (fastest FWD dsm in the world) tuned it with SAFC II...my car dyno'd 242 HP x 268 Torque. I'm running 15lbs of boost. The car is very fast, but like I said...the fuel efficiency sucks ass.

Is there any way to increase fuel efficiency without losing power? I think auto with all my upgrades is really killing my mileage.

ROW

I'm guessing that you fuel economy isn't related to your transmission, but I could be wrong.

There are some inefficient performance torque converters out there that could theoretically cause poor mileage, but your 2800 rpm high stall sounds to be just about a stock converter.

-John

 

[10minutecar]

Ok, thanks. Does anyone know how to bench test with a propane torch?

I forgot to post that my brother's GSX is an automatic, does anyone know what kind of mileage it should be getting? I know it will always be worse than a 5-speed.

Right now he is probably getting about the same milage as AzhigherTSI.

Is there any way to improve an auto's gas mileage so it is at least decent? Or is it pretty much hopeless?

 

[n0va91TSI]

I only get 170 miles off a full tank. prolly cuz Im a maniac and never shift below 4K (usually higher) and never use fifth gear (the gear for wussys).

If u have a fun car. Have fun. You want to drive slow and get good milage get a honda barf like my grandama.

 

[Rice Over Wheat]

Well yesterday I drove 100 miles on the highway at about 85, and I used approx a 1/3 tank which isn't too bad. Perhaps I'm just getting some poor city mileage. I raced about 4 cars at WOT a couple times each on that previous tank so perhaps that had something to do with it. I just don't remember that wiping out so much fuel...like 50% efficiency. Is that normal?

ROW

 

[Sayajin]

Ummm, I can understand not shifting before 4k RPM, but why would I want to drive at 90mph in 4th gear? Sorry my first manual!


-Sayajin

 

[1Quick99GST]

It seems like you guys all have really low gas milage. I get 300-320 per tank (from fill till the light STAYS on). I fill up with 93 octane and I have a HEAVY foot. I hit 5-6k RPM regularly, and cruise 2500-3000 - mostly stop and go stuff - very little interstate driving. Check my profile for mods. Guess I'm just lucky...

 

[noz]

Originally posted by 1Quick99GST
It seems like you guys all have really low gas milage. I get 300-320 per tank (from fill till the light STAYS on). I fill up with 93 octane and I have a HEAVY foot. I hit 5-6k RPM regularly, and cruise 2500-3000 - mostly stop and go stuff - very little interstate driving. Check my profile for mods. Guess I'm just lucky...

damn fool its because you don't pump til ur light goes on!!
most of us pump when the needle is close to E and not when the light comes on, so thats like at the 9-12 gallons of refill mark, ur'll probably at the 13+ when refilling. If I WOT my car a lot and don't pump til light comes on, i will hit the 300 mark easily too..
I never let the car run so low on gas that the light comes on though.....for some reason,iono which, i think its bad for the car.

 

[Lazybuddy525]

Just do what I do. I got over my pride and bought an old Geo Metro. Use that for a daily driver. The old ones get like 60 miles to the gallon and that isnt an exageration. I know they're pieces of crap but theyre only like 300 bucks so if it breaks just buy a new one. Besides not too much pride can be lost cuz you know you have a sweetass car sitting at home in the garage.