I was at ~28 mpg city, when I was using my stock exhaust. I through in a 2.5 in cat, and a N1 knock-off catback. Now my gas consumpion is at 18 mpg!!! What gives?... granted I get a better response, and my boost is alittle higher (~5 psi on my gage, previously I was at 4 psi, using a 5.6 wg spring).

Basic info on my setup...

B18B
T3/T4B turbo
log mani
intercooled
FMU
tial wg using a 5.6 psi spring
2.5 dp, cat
and ~2.38 catback

Please don't give me flack for not upgrading my fuel management. I've got everything I need to run something else, but just haven't got around to it.

Any ideas? tia.

 

Maybe you want to hear the sound of the exhuast and your driving more aggressively. Or, the turbo is able to spool easier and your using that to its advantage and boosting, lowering mileage?

 

maybe you need to "get around" to getting that fuel system to par and get tuned. gas milage should be fine then

 

thanks for the quick replies...

I don't my driving habbits have changed. My office is like 3 miles away from my house. I doubt I go over 3K rpm in my commute. I have been driving less on the freeway though. But then again, I was getting 36 mpg on a trip that was exclusively freeway miles.

and regarding the second response... why even bother posting? I'm quite sure people have been running FMU for years, and have not seen big drops in mpg's. I have been using my FMU setup for 2 years now.

 

i took my exhaust off on the dyno one time last year, and the car ran SO much richer that i lost 60 horsepower.

get engine managment and tune the thing. my beater gets 32mpg and runs 12's

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Turbo-charged &raquo;</TD></TR><TR><TD CLASS="quote">i took my exhaust off on the dyno one time last year, and the car ran SO much richer that i lost 60 horsepower.

get engine managment and tune the thing. my beater gets 32mpg and runs 12's</TD></TR></TABLE>

That's the odd thing... I was running the more constrictive exhaust and was getting stock mpg number, and I knew I was way rich. So, I would think throwing a less constrictive ehaust should be better.

I wonder if I have an exhaust leak before the 1st O2 sensor will screw things up. I did redo my dp when I put in the larger cat. I ran out of gas half way, and used a flux mig welder to finish up. I was crude at it.