The other day I bought a header. I had the car all jacked up with all my tools in hand ready to go. Then I realized that on the 98 DX the cat converter is mounted on the freaking stock header. My question is this:

If I go out and buy a new high flow cat converter and install my header, will I have to get custom piping installed for the exhaust? Or since I have a stock exhaust, is it possible to buy a cat back aftermarket exhaust that will fit this set up? Furthermore, will the car pass the emissions test?

Thanks for your help.

 

as long as you have a good cat your car will pass emissions.

You can get a Cat for the EX model civic or SIR (cat located under car on those models) and then have a welder modify your stock exhaust to match the cat.

 

well if you put your header in and cat your stock exhaust pipes will be in the way it will need to be shortened to accomodate the cat.

 

Just put the header in. It will bolt right up to the stock exhaust. When its time for smog just change it back. When you eliminate the cat, you must not put the secondary o2 sensor back in the pipe. Instead zip tie it up, safely out of the way. It is only there to check catalytic converter efficiency, by measuring oxygen. If it sees a lot, it thinks it works great. Normal air is about 21% so its good if the secondary o2 reads normal air.

 

I'm afraid I can't really buy that statement, no offense. There is FAR less oxygen in exhaust gasses than in the atmosphere (remember, the combustion cycle used it up?) and since the converters job is to reburn the gasses there should be even less O2 after the cat then before it. Leaving the sensor out has been shown to trigger "check engine" lights and revert the ECU into limp mode to help reduce emissions. I can assure you the OBD2 electronics do more than just read signal, they take action. That's why companies make O2 sensor simulators to wire into that 2nd sensor to trick it into sending the proper signal when it is unhooked. You can't just tie it back and leave it, unfortunately.

 

I didn't put mine in, my car is ODBII. I just wrapped it up in a ton of tin foil and actually left it under the carpet. Not the smartest thing to do but it wasn't that way long and the tin foil actually didn't get that hot, you could hold it in your hand. No CEL's and the engine runs the same. I've heard of other people doing the same. Be careful though, operating temp for these things is 600 deg.

s


[Modified by stevel, 4:25 PM 6/27/2002]

 

I didnt ask you to believe me. I offered my advise to someone that needs it. I've done it, it works, believe me or dont. I dont give. Can you assure me that my car is really running in limp mode with no CEL and no other symptoms that a qualified PORSCHE trained Technician such as myself would recognize.

You could always wrap it in foil? Tell me what that is supposed to do. They forgot to teach me that one at school.

 

The tin foil is just so you don't have to worry about it heating up stuff and maybe causing a fire, depends on where you put it I guess. It just insulates it. Being that you are a qualified PORSCHE mechanic I figured you would know that they get pretty hot.

s

 

I just did the EX header on the CX car...and I also did the resistor and capacitor trick.

I got the CEL after about 30 miles. Maybe I didn't solder correctly, I think I did though..or maybe the "trick" doesn't work.

I don't know how you guys leaving the sensor in the open are not getting lights. This makes no sense.