5th gear - less MPG?

[My5ABaby]

How are you measuring gas mileage? The proper (or at least best that we can easily accomplish) is to fill up several times, measure how much gas consumption you've had, and then calculate MPG. Do this for both 4th and 5th gear.

Also, 2.5k sounds kind of low for 5th gear. I usually don't go to 5th gear until at least 55 mph (not sure on what rpm that is).

Finally, why do you have a TII exhaust on an N/A?

Originally Posted by Low Impedance

i have a theory on what might be the issue.

if your in 5th at say at 60, there isnt a lot of load on the engine. And generally, your foot on the gas pedal can vary a lot but not really change your speed. Whereas in 4th there is more load and you are aware of how much pressure your applying to the pedal. Because the TPS sensor will control fuel based on rpm as well as throttle position, you have to be pretty aware of what your doing with your foot.

Generally speaking im usually in 5th while cruising over 30 mph. that is were i find the best mileage. I had a lot of time to play with this idea at freeway speeds driving cross country in the vert and 5th got the better mileage but you couldn't really rest your foot on the secondary butterfly spring resistance like you can in forth.

For the S4 it's more based on the AFM, rather than the TPS. Although it is still useful for cruising, the TPS on S4's only goes to about 30% throttle.