Have any of you noticed your fuel economy drop after installing a y-pipe? I just drove back from a long road trip with the y-pipe installed and my milage dropped to about 25mpg (no city, all highway). I used to be able to get around 29mpg when doing the same trip, roughly same conditions and conservative speeds. Did I damage an O2 sensor? No MIL yet so I'm assuming everything is OK. The only problem I KNOW I have is a small exhaust leak that I haven't had a chance to fix. Any ideas?

 

Did you reset your ECU after the Y-pipe install? Did you use you cruise control at the same touring speed you usually do?

 

In theory the y-pipe makes your car run more efficient which equates to innreased gas mileage. Check you tire pressure because that can ruin gas mileage.

 

I noticed this at first too but reset my ECU and everything was all better and mileage increased slightly

 

I put on my y-pipe, b-pipe, and 5th gen muffler on my 97 SE. I reset the ECU and I'm at 260 miles with half a tank left. This is with mixed freeway and city driving. I'll probably fill up my tank soon and displace the amount comsumed in order to figure my mileage.

 

your mileage should go up..... but only if you can keep your foot out of the gas. I guess mine should have gone up, but not the way I drive it