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

 

[BoostActionBob]

any word if any of this worked i'm kind of interested on how the results are going to come out with this.

 

[birdii]

you may also want to check timing on the vehicle. mine had a problem with that and it was a little off timing. also while you were doing the tune up did you clean anything. if not you may want to take the throttle body off and clean it with some intake manifold cleaner. clean the tps and isc. throw the throttle body back on. get a new can of it and spray it in it opening and closing the throttle. use half the can for this. then start the car. it may have some problems running but just plug the throttle body with your hand a little bit while spraying with the throttle open. use the rest of the can on this. put everything back together. while you have the mas off clean that also. might as well its all apart anyways. once everything is together and you start your car it may smoke. don't worry its not bad. i keep good gas mileage records. and after doing this it jumped mabe 4 to 5 mpg. oh ya and make sure your spark plugs are gapped right. .028 to .030. what kind of spark plugs are you using. might want to look into ngk bpr6es. Good luck

edit: o2 sensor is a wise check also.

thx for the helpful reply im going to try this on the weekend.... but around 3 weeks ago i took my car to the mechanic and i got my timing belt, water pump, cover gasket, NGK Power Platinum BKR6EGP, MSD Sparkplug wires, fuel filter and pcv valves changed…. Before the all the new parts I was getting 300 - 315miles on a full gas tank…. I had 1,3,and 4 spark plug wires swimming in oil when the mechanic was about to change the wires so I had the cover gasket changed…. Now with all the new parts installed im getting 215 – 230miles on a full gas tank… i should be getting better mpg after this tuneup..... when the car was scanned nothing came up… i might have to take it back to the mechanic....

btw how do you test for a vaccum leak?

 

[PaulN]

and i got my timing belt, water pump, cover gasket, NGK Power Platinum BKR6EGP, MSD Sparkplug wires, fuel filter and pcv valves changed….

Is it possible the mechanic didn't put the belt on quite right and now your're out of time? That would be the first thing I would look at since your mileage issue started afterwards.

 

[Defiant]

"Miles per tank" is meaningless, all the more so with the DSM's flakey gas gauge.

"Miles per GALLON" is the only value that makes sense.

 

[VegasTSI]

Well, I think my 2g (95 talon tsi awd a/t) is getting bad gas milage. Only about 200-235 miles to a full tank , well until the gas light turns on. Is this normal? If not what kind of problems could lead to bad gas milage.

The car got this gas milage when it was bone stock , I recently added a new type rs bov and cai and it still gets the same gs milage. And I also changed the plugs/wires/oil

 

[Raph]

bad 02 sensor or bad coolant temperature sensor

is your thermostat working?

 

[pnishr]

First, check/replace your air filter (assuming you haven't done so, as you didn't list it). DSMs already run rich from the factory, so if you aint getting enough air in there, you're just wasting even more fuel. Then go ahead and check out your front O2 (do you have a CEL?) Also, check/replace your vacuum lines as needed. Many who suffer bad gas mileage or other basic problems just need to do routine maintenance. (to include O2s and timing) If at that point, you still get crap for gas mileage, check you FPR, maybe it decided to give out. Just some ideas. Maybe they'll help, maybe they won't. in which case, somebody else, help him out.

J

 

[xucpxeclipsex]

.. mine gets that kinda gas mileage now.. .. but ya.. it sux.. but i get a lil more than 200 to the tank..

 

[bane3d]

When does your low fuel light come on? Mine comes on around 180 miles and then I can drive another 100 or so. I get about 18-20 mpg. It's a 16.7 gallon tank and I've filled it with at least 15.5 gallons this morning. The gas gauge is not set right. To estimate your mpg. You:

1. Go to gas station and fill the tank up completely.
2. Reset your trip odometer.
3. Drive until you want to fill it up again.
4. Fill it completely up and then write down how many gallons you filled it up.
5. Look at your trip odometer.
6. Divide your trip odometer by how many gallons you put in.

ex. I drove 200 miles since I filled my tank last and I put in 10 gallons
200miles / 10 gallons = 20 miles per gallon

d

 

[exile]

Yeah the AWD gas guage on DSM's is HORRIBLE. My light comes on sometimes when I'm half tank, one day it'll be below half and the next at 1/4 then below half again. It's amazing. I get the light usually at 200, I usually fill up at 230, but one time I actually made it to 280 and was biting my nails the entire way to the gas station. I'm going to fill up a gas can when I'm at about 230 and see how far I can go before I can't go any further.

 

[Whiplash]

Anyone get the fuel tank recall done? Im getting it done on wednesday, as of right now I get 160miles on a full tank of gas. So maybe the recall is to fix the gas light coming on too early...anyone know?

 

[TJGoSurf]

How heavy is your foot?

[Posted by 206.100.227.72. This is added while posting a message to avoid misuse of WebWarper: see http://webwarper.net/han Example of using WebWarper: http://webwarper.net/ww/dsmtuners.com/forums/showthread.php?t=205205 ]

 

[VegasTSI]

Anyone get the fuel tank recall done? Im getting it done on wednesday, as of right now I get 160miles on a full tank of gas. So maybe the recall is to fix the gas light coming on too early...anyone know?

How do I find out about this gas tank recall you speak of?

I will check all my o2 sensors.. I bought a o2 socket a couple days ago just to have, go figure.

How do I tell if the sensor is bad or not?

And one more thing, Along with the low gas milage my car is running very slow. If by chance say I have a boost leak would that contribute to low gas milage? I recently put on a cai and experiance the same problems, but now I can really hear the car spool up but somtimes it will spool up and everything and no go , hardly any juice....

Thanks for all the help

 

[Whiplash]

Just go to the dealership and see if your car has any recalls done. If it doesnt then do them.

 

[brn2race96]

To get a accurate MPG, what you should do is fill the tank, (do not top off), and zero out your trip. Drive as you would normally and try to go as far as you can, now what you do is check how many gallaons of gas you put into the tank. You take the miles on the trip and divide by the gallons you put in. This will take away any issue with when your gas light comes on. You should be getting 25 city to 32 highway. I get about 19-20 in my 2g gst, in chicago which is worse then typical city driving.

But most definetly check you O2 sensor because mine went bad and i was getting about 8-9 miles per gallon. ONe way to check is if you have a air fuel gauge it will show you rich all the time.

hope I was some help.. good luck

 

[VegasTSI]

Yea, I live in las vegas, driving is rediculous here.

How do I tell if I have a bad o2 sensor...

 

[danameisoj125]

damn you guys are pretty lucky. i drive an 04 srt-4 and im lucky if i see 15mpg.

my car just got into a wreck so if its totaled ill get another dsm.

 

[95dodgeavenger]

i used to think the same thing.. then i watced this little thing called boost gauge kept it out of boost was getting 32mpg highway.... 430cc injectors dump alot of fuel when your talking about gas mialage... keep it out of boost and ull be happy

 

[Defiant]

Yeah the AWD gas guage on DSM's is HORRIBLE. My light comes on sometimes when I'm half tank, one day it'll be below half and the next at 1/4 then below half again. It's amazing.

It's because you have two tanks, and the low light sensor is on the passenger side. A hard right turn will turn the light on early, and as the returning fuel from the engine runs through the jet pump from the driver's side, it'll re-fill the right side to turn the light out again. Many times.
But the gauge does still suck.

 

[Defiant]

Anyone get the fuel tank recall done? Im getting it done on wednesday, as of right now I get 160miles on a full tank of gas. So maybe the recall is to fix the gas light coming on too early...anyone know?

It's for leakage around some of the fittings. If there was enough leaking to account for a mileage loss, DSMs would have a Pinto reputation. Nothing to do with the gauges.

 

[ddavisaf]

How do I tell if the sensor is bad or not?

You'll have a check engine light and your spark plugs will have carbon deposits due to running rich.

And one more thing, Along with the low gas milage my car is running very slow. If by chance say I have a boost leak would that contribute to low gas milage? I recently put on a cai and experiance the same problems, but now I can really hear the car spool up but somtimes it will spool up and everything and no go , hardly any juice....

Run a boost leak test. A boost leak will definately cause bad gas mileage.

http://www.vfaq.com/mods/ICtester.html

 

[rampridersrider]

I used to get shyte for gas mileage. 150-200 on a full tank if I was lucky. My upstream O2 sensor was shot. I replaced it and now get about 280-300 before the light comes on. I filled it up the other day and ran it till it ran out of gas. 340 miles is how far it went and I was running it at about 80% highway 20% city with a half heavy foot. I get roughly 25 mpg on average.

 

[VegasTSI]

Well, late last night I took out my battery/tray for about 1 hour while running a powerline for my stereo. And before I started the car up I tightend everything I could get a screw driver onto. Going from my condo to my parents house the car ran beautifully. Might have built up knock codes and retarted timing? I will find out today when I drive it. Might be a bad knock sensor if that is happening correct?

 

[rampridersrider]

Could also have been an O2 sensor code that you cleared off. The motor started to run normal again and it will take a little bit of driving before it realizes the O2 sensor is shyte once more. Thats how mine worked.

 

[VegasTSI]

did you get a check engin light by chance? because I have no check engin light