am thinking of aftermarket cat back exhaust, I know lots of you have done this.

the mechanic I use told me that dropping the backpressure can 'confuse' the O2 sensor causing the ECU to richen up the mixture, maybe dropping the mileage. I had always thought that the mileage was supposed to go up (if anything) as the flow improved...

Does this make sense? has anyone seen decreased MPG as a result of changing exhaust??

 

No, I have actually seen a 1-2 increase.

 

it might affect the MPG, but you gotta pay to play

 

I've notice no change.

 

Haven't ran a full tank yet. Not sure if it's increased or decreased yet.

 

When you have mods that increase your air flow, the ecu will increase the amount of gas that it pumps into your engine, hense decreasing your gas mileage. But your not going to see much of a difference with a cat back. with headers, definately noticable. Dont worry, its not going to break you.


By the way, Im just curious what are the gas prices in new Jersey?

 

Hey qwill.. you're so-cal, how many total miles do you get (you said it increased). And when do you fill up? I usually fill up right when the indicator light turns on. (And fill up @ a 14-15 gallon tank).

 

~$2.25 for premium, still closer to $2.50 in some spots.

 

It's actually the opposite -- intake/headers/exhaust tend to improved MPG. The problem is that added power mods tend to have people make the most of them, and therefore they're a little heavier on the right pedal and live in the higher end of the RPM band thus making apparent MPG worse or at least a wash.

The 'adding this mod will make my MPG better' is a common ploy that most of us use to convince wives/SOs that our intake/header/exhaust purchase is a wise decision.

 

About 320 or 310. I get about 22-23mpg. And I don't drive like a grandma either

I too fill up at the indicator light