i have a 94' A4 Z28, and im getting about 130 miles to a full tank on 87 octane. its all city driving with a few highway miles a week. what could be causing this horrible gas mileage? anything i can do to get it up?

 

Check all your vacuum line connections. Also, check to make sure no vacuum lines have holes in them. Are you getting any heavy gas fumes when you get out of your car at all? Are you getting a check engine light? Check underneath your car while it is running and make sure you arent leaking anything. Stop the car and wait a few minutes and start it agian, check the underside for leaks.

 

everything is fine, checked all the lines, no leaks. no heavy gas fumes either.

 

You said you were running 87? That is most likely your problem as the LT1 was designed to run on 91 and with anything lower you will risk detonation,have less power, and worse gas mileage.

 

Also check your air filter and make sure your catalytic converter isnt clogged or hella old

 

a good tune up wouldnt hurt anything either, plugs wires air filter oil change ect.

good luck

 

I ran 87 for about a month and got 240 or so to a tank. Octane rating has little to do with milage and power, it has to do with compression ratio and knock.

I would be looking at tuning it, getting a tune up, and reading what codes it might have.