I replaced fuel filter, plugs, wires, No Cels 93 si with b18b swap, i had another post but this should clear it up with the title of it. Spark plugs are white. only mod is intake and 3 inch exhaust no cat. stock p75 ecu. just doesnt make sense how can you be running lean but getting bad gas milage?

 

anyone had this problem before? Please help me!

 

no cat = no back pressure, this hurts the mpg's

Also the 3" exhaust pipeing doesn't really help your problem.

 

Feels like the ecu is pulling timing because the car has rough acceleration at times

 

Anyone have any guesses?