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

 

[o0-TaLoNbOy-00o]

my car is get bad gas milage its killing me does anyone have and idea wut it is?! has anyone has this problem?!
its a 95 tsiawd auto and so far ive changed my front O2 sensor and the rear O2 sensor isnt connected..but i was told the rear o2 is just to see if your cat is working but i have no cat.
ive tried a diffren maf and injectors
i need help im get owned when my gas bill comes and its like 500-600 bucks

 

[danny_l_2005]

You should check for boost leaks. Do a tune up; change plugs and wires and filters. If you have a 95 tsi awd why are you posting in a N/T section?

 

[mitsuclipsegsx]

Fuel filter.

 

[o0-TaLoNbOy-00o]

whops!..my bad..maybe the mods come move this thread.
anyways how can my fuel filter give me bad gas milage?

 

[dan95tsi]

What kind of mileage are you getting?

 

[xveganxcowboyx]

Sounds like a good tune up is in order.

Check your timing.

 

[PaulN]

All of these can cause poor gas mileage:

Dirty Air Filter
Leaking Injectors
Fouled, Faulty or Incorrect Spark Plugs
Bad PCV Valve
Bad Spark Plug Wires
Faulty or non operationg O2 sensors

I'm sure theres more. Have you checked or replaced all of the above?

 

[o0-TaLoNbOy-00o]

What kind of mileage are you getting?

i was getting 180kms a tank..then i changed my front o2 now im getting 230

All of these can cause poor gas mileage:

Dirty Air Filter
Leaking Injectors
Fouled, Faulty or Incorrect Spark Plugs
Bad PCV Valve
Bad Spark Plug Wires
Faulty or non operationg O2 sensors

I'm sure theres more. Have you checked or replaced all of the above?

yes all of the above has been checked or replaced..but i only have the front o2 sensor in

 

[o0-TaLoNbOy-00o]

anyone esle have any ideas?

 

[exiletalon]

anyone esle have any ideas?

your O2 sensor might appear correct- it may be loose or incorrectly connected elsewhere, your rear O2 should be wrapped in tinfoil and connected in its appropriate, think- why wouldn't a fuel filter cause the problem- if it gets clogged then less fuel can travel through- also, get some fuel system cleanser ( lucas,etc..)- your injectors may be be clogged.

 

[xveganxcowboyx]

anyone esle have any ideas?

Unless you've covered all those bases, you've got a pretty good list to get started on.

 

[o0-TaLoNbOy-00o]

ok it already has been answered above but ill answer it agian

air filer = replaced
injectors = cleaned/replaced
pcv valve = replaced
plugs and wires = replaced
02 senors = front one changed/ rear one not changed

if put fuel system cleaners in the fuel tank

the only things i havent checked are

fuel filter
fpr

 

[titogs95]

Ok, more Ideas!
Have you check with a datalogger for your fuel trims? are they really high?
If so try to control it with the Safc. and go from there....

What is temperature of the coolant during normal function? I read somewhere in here that at low Coolant temp make the car run rich until it reach certain temperature.... so check coolant temp sensors.

 

[tbob2985]

i just starting noticing this after getting my mbc installed and turning the boost up. I have new plugs and wires (about 4K miles on each). I think i have a boost leak. I'm getting it checked out next weeK. I am going to do everything else that was listed above and see how that works too.

 

[KottonMouthTSI]

maybe you already know this, Or maybe you dont.....But In my car, and most cars, The Gas gauge is wrong. If your only putting in 10 gallons, when your on empty, you have another 6 gallons of gas. We have 16.7 gallon tanks. My car will say empty, and Ill go fill up, and it will only take 10 gallons, So i have another 100 miles to my tank atleast.

 

[PaulN]

i was getting 180kms a tank..then i changed my front o2 now im getting 230



yes all of the above has been checked or replaced..but i only have the front o2 sensor in

Do NOT go by miles per tank. That is just plain stupid (not to be rude or anything). It is known that the gas gauges in these cars are flaky/incorrect at best. My guage tells me I am out of gas at 290 miles on the tank, but when I fill up it only takes 11 or so gallons to fill up. (Just did it yesterday morning, as I always do. 296.5 miles on the tank, took 11.146 gallons to fill) I know I get 26 miles per gallon, so I know even though my guage says I am empty and the light is on I still have close to 100 miles left in the tank.

Again, You need to go by miles/kilometers per gallon and not miles/kilometers per tank.

How do you do that you ask? Well, it's easy. Simply fill the car up, zero out your tripometer, and drive until you need gas again. When that happens go to the gas station and FILL IT UP. Now, take the miles/kilometers on your tripometer and divide it by how ever many gallons it just took to fill the car up. This is your miles/kilometers per gallon. This is a true measure of your gas economy, or lack thereof. Not how far you go one one tank based on your in car gas guage.


Using my numbers above, I got 26.60 miles per gallon on my last fill up. Doing the math I would have got 399 miles out fo that tank because I know what mileage I can get. If I would have solely relied on my guage, I only got 296.5 miles. Huge difference.

 

[CRiXman]

Do NOT go by miles per tank. That is just plain stupid (not to be rude or anything). It is known that the gas gauges in these cars are flaky/incorrect at best. My guage tells me I am out of gas at 290 miles on the tank, but when I fill up it only takes 11 or so gallons to fill up. (Just did it yesterday morning, as I always do. 296.5 miles on the tank, took 11.146 gallons to fill) I know I get 26 miles per gallon, so I know even though my guage says I am empty and the light is on I still have close to 100 miles left in the tank.

Again, You need to go by miles/kilometers per gallon and not miles/kilometers per tank.

How do you do that you ask? Well, it's easy. Simply fill the car up, zero out your tripometer, and drive until you need gas again. When that happens go to the gas station and FILL IT UP. Now, take the miles/kilometers on your tripometer and divide it by how ever many gallons it just took to fill the car up. This is your miles/kilometers per gallon. This is a true measure of your gas economy, or lack thereof. Not how far you go one one tank based on your in car gas guage.


Using my numbers above, I got 26.60 miles per gallon on my last fill up. Doing the math I would have got 399 miles out fo that tank because I know what mileage I can get. If I would have solely relied on my guage, I only got 296.5 miles. Huge difference.

Note taken but...Its also depends which way a person prefers perceiving this..

Although..

Question 1:

If your full tank is 11.116 gallons and your miles per gallon is 26.6 doesn't the math equal to 26.6 x 11.116= 295.6856 miles per tank??

Or are you including the remainder of gas in your empty tank + 11.116 to get that extra 100 miles??


Question 2:

Driving with a light foot (almost no heavy footing) I get 230-240 miles max until I believe I need a refill. And when I do a refill, I fill it up approx 50.5 which is 13.340 gallons. Should I be considered as having excessive fuel consumption? Or is this normal? By the way my car is almost bone stock.

C.

 

[PaulN]

Note taken but...Its also depends which way a person prefers perceiving this..

Although..

Question 1:

If your full tank is 11.116 gallons and your miles per gallon is 26.6 doesn't the math equal to 26.6 x 11.116= 295.6856 miles per tank??

Or are you including the remainder of gas in your empty tank + 11.116 to get that extra 100 miles??

15 - 11.146 = 3.854 GALLONS left in the tank. Multiply that by my 26.60 Miles Per Gallon Average and you get 102.5164 of travel left in the tank


Question 2:

Driving with a light foot (almost no heavy footing) I get 230-240 miles max until I believe I need a refill. And when I do a refill, I fill it up approx 50.5 which is 13.340 gallons. Should I be considered as having excessive fuel consumption? Or is this normal? By the way my car is almost bone stock.

Using your numbers, you would appear to be getting 17.99 Miles Per Gallon. Is this all city driving or what? My car is driven 90 miles every day on the Highway in moderate winter tempuratures, usually 30 to 40 degrees and I average about 26 miles per gallon this time of year. Last fall I was pushing 28 miles per gallon. Driver habits and environment will play a role in your miles per gallon, sure, but I am not an expert on the causes. I was just simply pointing out that using your fuel guage and how many miles you drove on that tank is not a good indicator of your fuel economy.

C.

See above

 

[95TalonOwner]

Clogged cat maybe? After I chopped my cat off and ran straight dp, on my winter beater I got 50 more miles to a tank. And yes, my tank was very close to empty when I look how many miles I went. I usually drive until my engine bogs waaaay down when I make a turn. Then I know it is low on gas. When I go and fill it up, I usually only have one half gallon left.

 

[CRiXman]

See above

firstly thanks for your response...

Concerning question 1 I thought as much.. and thanks for clearing the doubt. That way of caluculation is probably the most accurate.

Concerning the second point. Yes..sorry I forgot to mention.. Mostly highway cruising. I would say out of 235 miles, 205 mile or so on the highway, and the 30 rest in city and sometimes city traffic.. And your 295 miles/tank? Highway and city?? or??

Bogged Catalyser hmm... How would I clean it? can't eliminate Cats in Switzerland unless your prepared to pay the fines..

Also just for the note.. When I put my FMIC I got better mileage about 20 miles or so..

C.

 

[PaulN]

Very little city driving for me. It's all rural highways and country roads.

 

[siceclipse]

So what's the deal with the rear o2 in tinfoil? How does that whole thing work? What does it actually read that you can get away with that?

Right now I am throwing a CEL after 7000 miles of having a test pipe. The CEL is P0420 Catalyst Below Efficiency Threshold... and my last tan is not going so well. I just replaced the plugs and BPR7ES and gapped them to .030.
I'm going to check for boost leaks still but I want to know more about the rear o2 in tinfoil.

Thanks in advance!

 

[blackgst256]

Ok so i had three quarters of a tank yesterday and now im empty and i only went 80 miles. I drove back and forth to work and driving around town and thats it. I hardly let the turbo spool up at all nothing above 3500 rpms because my clutch is starting to go so it slips in higher rpms. Could my clutch going be the reason why im getting about 8 miles per gallon or do you have any other suggestions why it could be happening??

 

[hellotbone]

I would start by testing/changing your O2 sensor. If that goes it makes the car default to pig rich and burn fuel like crazy. That happened to me. Other then that fuel leaks or a pesky neighbours kid that can't afford gas

 

[blackgst256]

yea actually my bottom o2 sensor isnt even hooked up right now because the guy who had the car before me messed up the wires and i didnt not have time to fix it yet. but i have been driving it for like a month and its just now starting to get bad