Sk8runeg

iTrader: (11)

Lately my gas mileage has just been getting worse and worse.... It started that I would get about 16-17 miles per gallon, then it slowly got worse and now I am getting 12 MILES PER GALLON!!!

Car is A4 and has:

Pacesetter LT's/ORY
Spintech muffler
SLP Lid/Bellow
Home Ported TB
3.73 gears
Tuned by ESP

I just changed the plugs back to TR55's because I was running nitrous and had TR6's gapped at .038. I dont knaw what is wrong though..... I bought a fuel filter so I am going to do that and I want to bring it to a GM dealership to get the injectors cleaned.

Also, the car smells terrible. I have a minor exhaust leak where my AIR block-off plate is, but I dont think that is causing it to smeel the way it does or at least not all of it.....

Any suggestions would be great guys

Thanks
-Scott

hammertime

iTrader: (1)

If your mileage is that bad, and you don't have a cam or a stall, I would start with the front O2 sensors. If you want to be sure, you can have the dealer check their output to see if they are working. Otherwise, they are relatively easy to replace and should considered a maintenance item.

Grimes

iTrader: (3)

I would take care of that leak by the AIR fitting as well, a leak in front of the O2 sensors may screw with their operation.

jmilz28

iTrader: (13)

You need to:
Get rid of intake leaks
Get rid of exhaust leaks
Clean injectors (as you mentioned)
Replace front O2s
Clean/replace air filter

Do that and see where you sit. My guess is you get back to 16ish or better, depending on your right foot.

May or may not need to get it retuned once you do this "tune up".

Big downside is your 3.73s, those hurt you big time. Also some variables are important, how uniform your gas quality is, and how heavy your foot is.

jlrz28

iTrader: (7)

Buy a can of injector cleaner before you go and spend big bucks on a "professional" injector clean.

5w20

iTrader: (21)

fix this first before you try anything else

Sk8runeg

iTrader: (11)

well i just went on a small trip to my uncles... On the way home I filled up and tested my mileage. I got 14.2mpg on the full tank

I filled up and drove 45 miles home and decided to check it again cause it was all highway driving. I got 22mpg on the ride home WITH punching it 2 or 3 times going like 75 the whole way...

So, it seems like the part thats hurting me the most is city driving, but that should still be around 14 or 15 if im getting 22-23 on the highway, so my average should be around 17 or 18...

I will check the air filter and fix the leak, but the car is tuned and isnt throwing any front o2 codes so could they still be bad?

Texhotrod593

iTrader: (7)

All of these guys sound very knowlegable about this problem. I would get rid of any exhast leak and vaccum leaks i.e. the intake leaks. I would also check the output of you O2's. It looks like you probabaly had to extend your o2's during installation of your ORY and any header installation. Those stock o2's are great for stock setup but after that many years they already should be replaced...and if you did headers/ORY you probabaly burnt the small heater up inside of the O2's because that exhaust setup will run a little bit colder compared to stock setup causing the heater element to get hotter hence burning up! If you do have to replace the o2's go with the corvettes of your same year REAR o2's. Theses are already longer for the installation and the heater element is much "beefier" for you colder running exhaust. One more thing to check....If there was anyway go ground down the wires for your o2's maybe by dradding them etc... you could most def. have shorted the eng sensor fuse. this fuse controls all of your sensors incuding your MAF MAPP etc.. I think its only a 15 amp fuse or something. Good luck good man!!!

BlackScreaminMachine

iTrader: (17)

Just factor in the weather....

Colder Air = More oxygen dense air

More Oxygen = More fuel required

Colder Air = Longer the car stays in Open Loop mode

xBROKEx

iTrader: (7)

are you throwing any codes?

lilbuddy1587

iTrader: (1)

Seafoam

92SilverSHO

iTrader: (3)

im getting 11.9 with a granny foot in cold weather and city driving. After i put the headers/intake on, the car has gotten worse mileage city wise. I get around 11-12city and 28hwy and thats not going over 2k rpms shifting.

GT Griller

iTrader: (8)

I dont have any suggestions that havent already been mentioned but....I can tell u that 3.73's dont affect ur gas mileage that bad at all....I know cause i have had them for 4 yrs now.

hammertime

iTrader: (1)

When you are trying to check your mileage, why would you be 'punching it 2 or 3 times'? You do know your driving style will have a lot to do with the mileage you get.

Honestly, a short drive cycle with just a few miles isn't probably enoug to tell you much, unless you are really good at controlling the exact fuel level you stop at - when the pump kicks off isn't really good enough unless its the same pump each time.


Try fixing the leaks and driving it like your grandma is with you. Pretend she's gonna get you heads and cam for Christmas if you convince her you are responsible enough...

J/K, but you get my drift