I have a 89 formula and my car gets around 7 or 8 mpg on the highway.....any ideas???? Hope I put this in the right board if not sorry..............anyway how about some advice.....

 

What motor is really in your car? The "HO" motor was carbed, and was discontinued after 86; you probably have the lower-output TPI 305, with the "peanut" cam, since you have an auto trans. You probably also have 2.77 or at best 3.27 gears, which should give decent highway mileage. What other mods if any have you done besides what's in your sig?

 

There's many things that can cause bad gas mileage. I suggest changing the coolant temp sensor. However if any of the sensors are malfunctioning, they can cause bad mileage. Catilytic Converter maybe??

 

Well you could be right it might be a LO3.........but anyhow. The cam is a 460 comp. No converter 3" pipe all the way back. No S.E.S light. Just replaced the coolent temp sencor and the Oxygen sencor, Throttle Pos. Sencor. and the MAP sencor. None of this helped. And the car does have somewhere in the neighorhood of 2.73's or so. The best gas mileage I ever got out of it was around 10mpg. Anything else that you need to know let me know.


Thanks,

I DRAG 2

 

What about taking it to a shop and getting it thrown onto a scope? I believe that'll help you if it's something electronical or something right?

 

well thats a good idea, but on the bad side I work at a chevy dealership and already done that and we can't find nothing wrong...................?

 

Exactly which Comp cam do you have. Does it have a rough idle.
What other mods do you have. Sounds like the computer is not going into closed loop mode. A long overlap cam will really thow off a stock computer controlled car.