I've had my Z28 since March and I've gotten crappy gas milaege ever sice. I didn't really car because I loved the car and I worked alot of overtime at work so I didn't notice it at the pump too much. But now since I've been laid off and gas prices going sky high I can't take it much longer.

In March I changed the following

spark plugs and wires
thermostat to 160 degree's
alternater
battery
clutch
put underdrive pullies on it
skip shift eliminater
new temp sensor from RK sport
K&N ram air kit and K&N filter
gutted my cat

I know somethings like the batt, alt, and clutch may not have anything to do with it but I just thought I'd list every thing I've done to it. I've drove it easy for a week and got around 240 miles to a tank with a gallon or so left in it and I've also drove it hard and played around in it too and get around 225 miles to the tank. I also don't run my air conditioning either.

Today I topped off my tank with 7 gallons of gas and I had only went 79 miles since I filled up last Thursday. Any suggestions please.

 

change your o2's. that will probably be your biggest gas saver, if they're bad that is. fyi if you do change them dont go bosch get ac delco.

 

I'm not getting any SES codes so could that mean the O2's are still good.

 

well not being an obd2 car its possible not to get a ses light, a month after i done my exhaust one of mine went bad and i got no codes the only way i found out was with my scanmaster

 

One of my o2's is bad, I have about 11 mpg like you and I'm not throwing any codes. So it doesn't necessarily throw codes.

 

an easy way to check is to take it to your local auto zone or advanced auto and tell them to scan it to see the values of each o2

 

hey luckyou, what kind of gas mileage do you get with everything running good, i have close to the same set up as you and im getting around 16 mpg?

 

I have the following mod's in my sig and last tank I got 16mpg's with the A/C on 100% of the time, except the few times I had to unleash the beast. I am running the Bosch o2 sensors and I am going to trade them out for some AC's and see what happens then.