So I bought a parts civic that had the subframe rusted out for 200$. It had a header on it, my exhaust had the muffler rust off so I replaced my entire exhaust and installed the aftermarket header. I have a header (with all O2 sensors functioning properly) the resonator thingy (it’s hollow but has some little holes in it) and a muffler. Since I’ve done that my gas image is 26 MPGs HIGHWAY driving 😳 it’s consistently about 26 too for 2 months now. Anybody know some tricks I can do to help this mileage improve. Used to get 31-32 consistently. It’s a 1997 DX four door with 255,000 miles. Automatic

P.S. soon I will be posting pictures of my repaint job I will do to it! I know useless additional information sorry lol I’m just excited to paint it!

thanks for your help in advanced.

 

I said resonator has some holes in it I mean on the inside of it lol id you look in it

 

If I am remembering correctly, the D16Y7 has the catalytic converter in the exhaust manifold design.

Sounds to me like you changed to a D16Y8 exhaust manifold design and removed the catalytic converter for a test pipe.

Changing just the header design to one without a catalytic converter will change your scavenging properties and then removing the catalytic converter will change it even further. If you want your fuel economy back, return to the stock header/catalytic converter setup.

 

yea you are correct. The catalytic converters is in the stock manifold that was removed. When the car is running it smells rich.

I know this may sound dumb. But is this something I could pay a tuner to solve? I don’t mind spending a little money keeping it the way it is but if I have to go back to the stock exhaust manifold I will. That makes for the reply.

I know what I’ll do. I’ll weld in an aftermarket catalytic converters and put the O2 sensor behind it (like it is from the factory) and that should solve the problem.

 

You should have 2 O2 sensors, upstream (before or top of cat) and downstream (after cat).

It's the upstream O2 that is most critical. The downstream is there to report on cat efficiency only.

As for a tuner, you would need a tune able ECU solution. Going OBD1 may cause challenges for inspections/emissions. OBD2 Honda ECU's are not really tune able.

 

Yea I should have specified TWO O2 sensors. Well I live in WV and we don’t have emissions. Sounds like too much hassle to me I may just go back to stock. Thanks for your input.

 

Post all CEL codes.

 

zero check engine light 💪🏽

 

owned the car for ten years and only time CEL came on was when I was resetting time on my distributor when I put a pin in that thingy to stop the computer from adjusting it. Went away after I removed the pin.

 

Does the cluster CEL currently work? Sometimes the bulb burns out.