Before I had a freeflowing ghetto exhaust.
Mani--> Flowmaster 40 and ended at the axle.

So now its
Mani-->Flowmaster 40- Glasspack --> glasspack. Its incredible how much quiet it is.

BUT...

Beffore I was getting consistent 17mpg in town. With the addition to the exhaust, it has dropped about 5mpg. I barely got 215 miles last tank. Whats up!? My MPG is about 12 now. Could the exhaust really cause that?

 

Bad O2 sensor?

That's the only thing that's down there TO be effected so I can't imagine it'd be anything else.

--Gary

 

So the added backpressure shouldn't affect the MPG much?

 

dont feel bad, i got 204 miles on the last tank, im about to sell th9is beotch

 

Glasspacks? Hummmm, that sucker could/should melt and clog up causing alot of problems including MPG.

 

they are all teh way at the end, its just temporary fix

 

No. The O2 sensor's effect on fuel consumption is nowhere near that much.

 

O2 sensor looks fine, and it doesn't show up in the CEL bank. Any other ideas?

I thought the lengthened exhaust (definately not tuneD) would lead to better MPG, less energy lost in noise...? Its interesting how much its gone down. I'm ranging about 210 miles. Before I was getting right arbound 280-300

 

make sure ur air flapper meter is good, if that is dirty it can cause it to stuck and make for bad gasmilage.

Yes, i did say flapper

 

Thats something I could check I suppose. Really though, if it were getting stuck, wouldn't the car just stall?"

 

With just an RB header leading to my stock main cat and cat back, and a gnarly large street port, I got 27mpg with my FC NA coming back from Washington one day. It was a 300+ mile trip on the freeway at 75+ mph. Restrictive exhaust won't cause that big of drop in MPG . .

 

I wonder what the heck then... It dropped right after i put that exhaust on. :/

 

update: The gas tank was leaking, had a leak half way up. I believe it was leaking soemwhere aournd 1-2 gallons per day.

I repaired the gas tank and back to my 75miles/quarter tank