Pretty new to my STi, so I have a fuel mileage question. It's a Stage 2 setup with an Invidia eql header, catted downpipe, apexi rs exhaust and k&n filter. Is running a Cobb custom tuned map from Cobb in Texas. I'm getting some pretty horrid highway gas mileage and was wondering if this was "just me" or something is maybe wonky with the tune. Driving 65mph in 6th gear for 10 flat miles = 27.7mpg. Awesome! Driving 75mph in 6th gear for 10 flat miles = 18mpg. Woah, that's weird. Driving 75mph in 5th gear for 10 miles = 23mpg. Uhhm ok? Wondering if this is something to do with the tune at 3200rpms? Or is it that at 3200rpms in 6th gear, the car needs boost with cruise control so it gets terrible mileage? Speed limits around here are 70, so I drive 75 a LOT. Thoughts, experiences?? I plan on heading to TopSpeed when I can take a week day off so I can get the numbers checked out and a possible tune by Doug, but figured I'd ask anyways. Edit: I played with the Stage 2 map, the economy map, S, S#, I, etc and I get the same mileage at cruise control highway cruising.
those don't mean shit. if you're taking your reading off your cobb - laf if you wnat a solid reading, do an entire tank. On my stage 2 setup, i drove an entire tank at 80mph and averaged 23mph (atlanta to savannah). On the way back, i did the economy tune, same thing.... hoppe, use the fucking search key, i posted shit about this some 3 odd years ago. brett said you're a pussy
edit (in a separate post) cruise control kills gas mileage. in the same post (you didn't check), i ran both foot on throttle and cruise, the average is 3-4 mpg difference
Tom I think your custom Cobb map (tuned by Tim Bailey who is just as good as Doug) is just fine. Your issue is probably more to do with load. You are at a higher rpm band at 75 mph and 6th gearing is such that it 'lugs' the engine at that rpm. So everytime you lug that engine the ECU dumps fuel ESPECIALLY if you are using cruise control. I learned very quickly to quit using cruise if I was being conservative.