Gas mileage problem.
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iTrader: (14)
Joined: Nov 2004
Posts: 1,653
Likes: 1
From: Michigan (Macomb or Lansing)
Gas mileage problem. 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?
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?
Launching!
Joined: Apr 2004
Posts: 254
Likes: 0
From: Roanoke, Va.
Well most LT1 guy i heard get an average of 20 mph with highway/street driving. I do about 80% of my driving in the city, i got an average of 15-18, and i'm not as easy on the pedal as most.
Does the car seem to be running weak? It sounds like you keep up with all the maintenance and that helps alot. If something is wrong with your compression it wouldn't run good at all. Unless you have a heavy foot, i know of anything that'd hurt your mpg if it was running good.
Does the car seem to be running weak? It sounds like you keep up with all the maintenance and that helps alot. If something is wrong with your compression it wouldn't run good at all. Unless you have a heavy foot, i know of anything that'd hurt your mpg if it was running good.
Launching!
Joined: Apr 2004
Posts: 254
Likes: 0
From: Roanoke, Va.
Does the car seem to be running rich at all? Either way, O2 sensors aren't much, and they can make you run rich by putting more fuel than air into the cylinder. If that doesn't work, all i know is try to stay off the right pedal alittle more, or get someone to look it over real good.
TECH Senior Member
Joined: Jun 2003
Posts: 9,339
Likes: 3
From: NYC metro area
you're probably running rich, like the others said. Might as well check wires and opti as well, but it seems kind of funny that you're car is running perfectly fine and your gas mileage is in the *******. 
Well it depends on what kinda city driving you're doing. If you're doing a lot of stop and go, then 12-13 sounds about right on to me. Take her on a road trip and then if it doesn't get 300 miles to the tank, then start looking.
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in town i only get around 12-13 also, but on the highway i get around 25-26. im going to change my wires, cap and rotor, coil, and add an ignition box as soon as it all gets in. i also plan on getting new o2 sensors. ill let you know if this all helps.
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