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

 

[Talon IV]

It does sound like an o2 sensor but if it is it will be throwing a check engine light. Venting to atmosphere will hurt your gas mileage too. Are you up to date on your routine maintenance? Little things such as air filter, spark plugs, gas cap, tire pressure and old oil all have an impact on your gas mileage. Keeping up with maintenance is a great way to prevent and fix a lot of common problems.

This! Plus like when I first got my Talon I could not keep my foot off the loud pedal, that hurts as well. Just do a double check like stated right above. It is the preventive maintenance that seems to hurt mpg's the worst.

 

[Tommy's]

are there any mods to the vehicle?

 

[ShadyGST]

It is the o2 sensor...

 

[eclipsemodder]

Yeah I jus got it so I don't know a whole lot about it yet. But it has a fuel pressure regulator with a gauge on it Aem tru time cams. The fuel pump cover and backseat was lifted up so it might have a high flow fuel pump not sure yet tho. And about the o2 sensor the front one that goes into the manifold with the long wires was hanging wrapped around the top radiator hose when I got it. And I didn't want to burn out my valves so I put it back in. And no check engine light not throwing any codes. Trying to make a good reliable DD. with a little bit of fun and decent gas mileage. I'll post pictures of under the hood tomorrow.

 

[mattasi]

Cool man. And just saying, make sure the oil isn't getting gas in it from running so rich. 100 miles per tank you say, dang I thought my old 3/4 truck was bad haha.

 

[eclipsemodder]

Lol yeah it sucks. Gotta figure out what's going on. I'm not losing or using oil so I don't think it's getting in the gas. I kinda think it's something to do with that fuel pressure regulator ?

 

[smokestack]

Bad gas mileage can occur from many variables. Some are bad plugs, fuel filter, uneven tire pressure. Start going through maintenance and checking everything.

 

[eclipsemodder]

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[Ehclipse]

I think i get around 150 miles per tank, city driving with lots of lights and stop signs. Im going to keep track on my next fill up and see what it is for sure

 

[Doubleot]

Haven't filled my tank completely for almost a year, I'll find out between today and tomorrow though.

 

[cl1ckclack]

i get 16-18 mpg with my GSX... 750cc injectors.

 

[edsgst]

300+ for a full tank. Normal driving for me is a mix of some highway and mostly stop & go city traffic. I usually see 22/23 mpg, but I will see 30-32 mpg w/ just highway driving. This is on E10 92 octane in a 2.3 stroker, with FIC 1050s, Keydiver/SAFC, T67.....

 

[Dsm304]

I think i get around 150 miles per tank, city driving with lots of lights and stop signs. Im going to keep track on my next fill up and see what it is for sure

150miles must suck specially with the price of 93 octane :/

 

[Ehclipse]

150miles must suck specially with the price of 93 octane :/

yeah i know thats why im jealous seeing how people on here get much more D:

 

[DSM1G90]

I'm bone stock and hit 22 in town (summer and 20 on winter gas) and can see 28 on the freeway. Not complaining, but do miss my 30plus with smaller 4cyl cars that I had.

Course, I never get the rev counter over 3KRPM's in town - I shift quick and easy.

I get on it on the freeway once in a while to blow out what little carbon is inside the cylinders...Just runs super...!

I also run my tires at 35psi .. that aids in reducing rolling resistance.

-DSM

 

[ShadyGST]

xcvzfgbdb

 

[GST_RIC_99]

i get about 340 -350 on a full tank with my auto 99 gst i use shell 91 gas all the time. when i 1st got the car i would get bad gas mileage like 220 or 250 but i was using cheap gas and i wasn't use to driving a turbo car i try not to let the turbo spool i let off and let it spool when i need to catch speed but other then that i guess i get good gas mileage

 

[xGrafitti]

Ok, So I'm having some pretty bad gas mileage in my GST and also my service engine light is on. After I researched a bit I found it could be my o2 sensor. Just want to get more opinions on it before I go and order the part. In the forum I read it said that the sensor could be bad and will also cause the light to be coming on.

 

[grothe3297venge]

You can know the exact problem if you hook up an obdII scanner..? Well not an exact but a good spot to start from!

 

[007jimmy]

Ok, So I'm having some pretty bad gas mileage in my GST and also my service engine light is on. After I researched a bit I found it could be my o2 sensor. Just want to get more opinions on it before I go and order the part. In the forum I read it said that the sensor could be bad and will also cause the light to be coming on.

If your check engine light is on, get the code read and fix the problems. There is no sense in trying to guess what it is. Could be a list of possibilities... If it were my bet you probably have more then 1..

 

[xGrafitti]

You can know the exact problem if you hook up an obdII scanner..? Well not an exact but a good spot to start from!

Well, 2 Oil changes ago I asked them what was throwing the light, they told me that it had to do something with the o2 sensor. But they couldn't be sure.

 

[grothe3297venge]

Go to autozone or some place that does free service engine light diagnostics and have them print it out and just work your way down the list!

 

[AngelOfPassion]

Well, 2 Oil changes ago I asked them what was throwing the light, they told me that it had to do something with the o2 sensor. But they couldn't be sure.

Most mechanics have NO IDEA how to work on DSM's. It is a way better option to find out the truth by looking yourself. Get someone to give you the exact engine code and search it in the forum search. You will most likely find someone with the same problem and be able to get it fixed CORRECTLY.

 

[xGrafitti]

Most mechanics have NO IDEA how to work on DSM's. It is a way better option to find out the truth by looking yourself. Get someone to give you the exact engine code and search it in the forum search. You will most likely find someone with the same problem and be able to get it fixed CORRECTLY.

Sounds like a good idea. [=

 

[slonkey]

I when I first got the car I had a cracked manifold. I filled it up and If I can really remember it was 450 range a tank on 93 pump. I just got a full tank of 93 last week. Fixed the crack by the way. Got a new manifold.

Anyway went through the tank and only got 230miles. In a tank! Please help. I don't have any cel or anything. Everything feels good. Drives no worse than from factory. Does have some bolt on mods but nothing has changed other then me fixing that header problem.