Alcon
I've a 1993 Honda Prelude 4SW SI that came w/a H23 and automatic transmission. I blew the engine and swapped in a F22B DOHC JDM engine. The problem I have is that the car gets very bad gas mileage about 15MPG. I thought it might be because I didn't have the knock sensor hooked up. But then I JB weld a nut to a blank hole above the oil filter and installed the knock sensor and I'm still getting very poor gas mileage. Any suggestions on what the problem might be or how to improve the mpg? Do I need to change to a JDM EMC? What is the correct model JDM EMC that fits the vehicle?

PS of course I replaced all the plugs and wires. I didn't change the distributor.

 

Yes, you need the P39 ECU to run correctly, which does not require a knock sensor. Also, did you do your fuel filter? Clean any part of the intake system before you put it in?

 

Will I need to change the engine wiring harness or just plug in the P39?

 

Nope