i was wondering how people who own 3rd gens are able to get 30mpg on the frwy. i have a 91 formula350 and it gets 10 in town 18 on the frwy if i am lucky. i have repaced the timing chain, water pump, knock sensor, spark timimng module, egr valve, egr solenoid, cap, rotor, plugs, wires, and i think a few other sensors. it is frustating to get poor gas mileage and i know it never had great gas mileage but when i see somone with basically the same set up as me and getting that kind of gas mileage i am jealous.

thanks

 

What gears do you have? A lot of it has to do with the way you drive. Start off slow never going past 1/4 throttle and let off the gas when coming to a stop more then 100 yards away.

 

Something is definitely wrong there!

You should get at least 15 or 16 mpg around town and 25 or so on the highway. Must be a sensor that is giving bad info.

 

Kind of a Duh...but have you changed the O2 sensor? How's the trans?? If its slipping I'd imagine that could hurt you too. TQ Converter locking up, I think that improves mileage?

 

yeah new O2 sensor as well, i dont drive it hard only when i am entering the freeway. it has been runing kind of wierd lately. My car for some reason threw a code 46 yesturday and for some reason after changing the egr valve and egr solenoid i am still getting a code 32, i cleared the codes after i replaced the solenoid and valve. anything/ideas would be great. i would just like a bit more mpg.

thanks

 

oh trans was rebuilt less than 2 years ago too and i believe i am running 343 or 373 gears.

 

sounds like the gears could be the problem,, what are your rpm's on the highway, at say,, 65? Mine with the pos 2.77 is like 1600 or so,, and I was getting 26, 23 with the supercharger on.

 

check your:
o2
timing
vaccume readings for vac leaks
compression check to check for worn cyl/rings
also could be worn/clogged injectors that are leaking fuel

 

keep in mind, fuel economy is not only determined by the engine and its peripherals, but the tires and setup as well. You need to have proper alignment and tire PSI as well.

 

well my rpms at 70mph is 2100 so it isnt to high i think, i wish i had a 6 speed but the 700r is good i guess for now

 

Thats not that bad, at 70mph i'm turning 3500rpm. I still manage to get 20mpg on the highway though.