Yeah I put that TB on like 2 weeks ago and the trip to Oregon was about a month or two ago. I got 15.3 mpg on the way there which is pathetic... I drive 60-70 mph the whole time with very short 35mph roads in between... I get on it maybe once there and once back but that's just getting to maybe 60 mph cant be hurting me that bad, and I have stock gears. I'm at 130 miles with this tank and I have maybe a hair over a 1/4 tank, so I might be lucky to get 170 miles. What do you think? Plugs and all that or get it checked out?

 

same here

 

That Accufab is killing your mileage is what I think. The car could be sucking more fuel to keep up with the additional air, but I don't pretend to be a certified mechanic or anything. Drop-in K&N and weld-in Flows would increase mpg a smidget if anything. I'd say have your car dyno tuned ASAP, that'll help her run better and show you and the tuner what's going on with her. If ya get her on the dyno, let a brother know what's up with a dyno sheet showing A/F and all that.

 

Im dyno tuning after I install ARH longtubes when I sell my atv. I havent noticed a difference in mpg after the TB though. I have been getting the same milage as a week before the TB was installed. I guess I wont worry about it though. My dads 04 Lightning gets pretty much the same milage as my Mach which is kinda funky, 5.4l s/c vs 4.6l n/a and both get the same mpg...

 

Everyone using 91 octane?

 

93 here.

 

Most run 93. Doesn't boost performance unless you're tuned for it. With stock tune it's just kind of insurance to be sure the car is running on atleast 91.

 

Good idea with the tune/lt idea, planning on the same thing here. But I swear for an n/a Mach that's low. Oh well, one of those things I guess. That mpg is right for a Lightning....bigger motor (SOHC?), more weight, more wind resistance. Around town I'm getting 22-23 mpg w/ 4.10s, but I think running 40 psi, shifting early and keeping it @ 60 helps that alot. Hope your eventual tune helps yours out though.

 

I'm tuned on '93. If you still have your knock sensors fully on, you might see an improvement using 93 over 91 if your car pulls timing on 91. The knock sensors in the Mach are oversensitive from the factory, so they pull timing earlier than they should. I've got my sensors dialed back in a tune, so I don't see timing being pulled now.

 

True that. Good point. Edited my post.