Re: Re-post Mileage Drop

From: Robert Trottmann (rotrottmann@davidson.edu)
Date: Thu Feb 25 1999 - 19:59:10 EST


If you did all that in one month, could the exhaust have taken place before
the computer caught up with another mod? If you did the intake on tuesday,
and the exhaust thursday, the drop in mileage on friday could have been the
TB. Although I have all your mods, pretty much exactly, I have not run into
problems w/ gas mileage, and I still average 16+ and 20 on the highway. If
I were you, I wouldn't blame the performance mods.....maybe something's
shot. The only mod we do not have in common is that I have the MSD and Ram
air hood, but I do NOT have a high flow cat, I have an 81,000 mile old cat,
so maybe that did somethin'????

James Thomas wrote:

> Com'mon folks, I only got three responses to this post the first time.
> There must be more folks than that out there that have some ideas or
> suggestions on how to get my economy back. Has everybody else gotten
> better performance and economy out of their exhaust work? One last time:
>
> Am resending this message as I did not receive an answer as of yet and
> did not know if it had been received. Have done the following to a 1994
> Std Cab 4X4, 5.2L, auto, 3.55 gears. Started with a Transgo shift kit
> then added Magnecor wires, brass cap and rotor, Champion truck plugs,
> MPI Super Street throttle body, K&N FIPK, Mopar Performance SBEC,
> DynoMax cat-back (2 3/4in pipe), hi-flo catalytic and new O2 sensor. All
> upgrades done within the last month or so. Everything up to the exhaust
> work gained very significant torque and throttle response and 3-5mpg
> city/highway. The gas mileage increase with the performance gains was
> just what I wanted. When the exhaust work was done I lost the mpg gains
> and then some. I went from getting 16.5 combined city/highway down to as
> low as 14.2. On strictly highway mileage I went from 20.1(best) to 15mpg
> at best now. I gained some nice breathability with the
> exhaust albeit at a high expense of economy. Has anyone else ever run
> into similar mpg problems with a combination like mine? Am wanting to
> add an MSD ignition control box and coil soon but would like to get mpg
> problems identified first. Any ideas why the exhaust work caused the
> mileage to go down?



This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:12:45 EDT