5" straight pipe and big mieage drop

[Yo Hoot]

I don't know if what I'm seeing is true cause you know computers and mileage.



Stock the truck was holding 17 . 5 or so.



I removed the baffle in the intake tube and the silencer ring. Almost no mileage reading difference.



After putting the 315 tires on it dropped to 16. 5 without correction



Now after installing the 5" system, my avg on the overhead is hanging on 12 mpg.



Did I lose 5 mpg by enhancing airflow, therefore MAF sensor adds fuel?

 

[CoastyAV8R]

I wouldn't say anything definite if your going by the overhead. Were you tracking fuel mileage by hand before the mods? I would say that is the more accurate approach to this. I can't see opening the exhaust up would hurt your mileage unless now your driving it like a madman...

 

[nickleinonen]

is the loud pipe/heavy foot syndrome coming into effect right now? i have 5" pipes on my truck [with muffler] and a gutted intake silencer pipe & silencer ring removed and a 4" hole in my air box. my fuel economy hasn't gotten worse [a little at first with wot all the time ] but now i have calmed down some and am watching the boost/pyro to keep them low as possable.



i also have 315's under my truck, but i haden't even burned 1/2 tank of fuel when i installed them [400 km]