I have a 97 z28 a4 with 113k miles on it I am only averaging 12-13mpg city driving in a normal fashion. I notice many people with lt1 fbodies get over 20mpg even in the city. I really want to figure out the problem is. I have all of my fluids changed, using durablend oil, i've seafoamed crankcase, fuel injectors, and the intake. I have new spark plugs and wires, cai, catback. I was wondering what i can do to fix my gas miles. I just switched my 160 stat to a 180 one. I only have 2.73 gears and my transmission seems to be working fine. Tires are filled to 35+ psi (max tire says 45psi but i fill them while cold)

What do you guys recommend i do to find exactly where this problem is coming from and what i can do to fix it. I thought it might be the o2 sensors but i dont want to change them if they arent bad. It may also be compression loss but that doesnt seem like a common problem on lt1s(where can i get that tested at?), It may also be an ignition problem but i dont believe so.

Any other recommendations on what i can do to pinpoint exactly whats causing my problem?

 

Wow...that's crappy mileage man. When I was driving mine this summer I was averaging 17mpg city. I still need to do a tune up on mine, I'm waiting till I get headers first. Anyway, it's possible it's the O2 sensors, you can goto a garage and have them hook up a scanner and let them see what kind of readings you are getting.

It seems like you've already covered the basic's so if it isn't the O2 sensors, then it might be something else. You might also be getting a little bit of injector leak down. Hooked up a fuel pressure gauge, key it up, and then watch to see if and how fast the fuel pressure leaks down. That's a possibilty. There are still a couple things that could be a factor, but it's easier for me to help diagnose when I am actually there in person.

 

sounds like a normal tank around the city to me