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.

 

Didn't you post this yesterday?

*edit* I was right

https://honda-tech.com/zerothread?id=1979828

 

Sorry all all for posting the same thing twice i couldn't find the original post.

moderator can delete this duplicate post

please dont post replays here

 

I also did the same swap 24 months ago. I came back to this forum after a few years absence trying to find a way to increase my '93 Si mileage... I also have an A/T.

But my mileage varies from 15 to 30 mpg depending on the weight of my foot. Suburban driving gets me ~22 mpg. At a steady 70 mph I'll get 25 mpg. At a steady 60 mph I'll get 30 mpg. 10 mph makes a big difference in my mileage. And I thought my mileage was crap.

Everything in my lude is stock except for the muffler and distributor. The ECU is the OEM stock unit. I have a single resonator behind the catalytic followed by a Borla 40059 stainless steel muffler. The distributor is a Moroso performance unit.

But still, I thought my mileage was bad. And I thought that the low back pressure exhaust might be the cause. Apparently not? What's your opinion? Is your catalytic plugged up? Could it be the Moroso? Do you know if there's a chip you can buy for these ludes?

Richard

 

i have a jdmf22b in my prelude and im getting bad mpg too, bars being going down quick.. i dno if its the way im driving or what.. if u keep it at a low rpm, ur saving gas right? or does it just depend on how far ur putting ur foot on the gas?

 

it depends on how much fuel ur sending. higher rpm's will consume more gas. Also fast acceleration (stomping the gas, pushing pedal to metal etc) will consume more gas aswell. Its a fuel pump electrically controlled in most parts. You push it in as far as it can go, the pump is going to push the maximum fuel it can flow.