I need to replace my exhaust. I'm looking into a 4-2-1 header w/ 2" out front to back with a good tail feather.

Is there something I need to be aware of about cat converters and O2 sensors? I live in e-check land with a 2000 hatch and wanted to know if there are certain things that make the check engine light go on if I get the wrong cat, or if there are emissions issues that I need to research and avoid, or just general knowledge to make sure I don't break something or ruin something.

Just looking to do it right the first time.


No boost here, none at all.

 

2000 hatch means Y7, unless you've swapped it. You'll need to extend your secondary O2 sensor wiring, and get an EX-style cat. As long as it's a real, proper cat, you'll be fine.

 

Okay. Good to know. I replaced my brake lines last year and noticed a cat under the car. Is this where its supposed to be then, or was the exhaust system replaced?

 

Your cat is currently in your exhaust manifold. If you replace that with a header, you'll need a cat that goes under the car. You can use an aftermarket header meant for a 92-00 civic single cam, and a cat from a 96-00 civic EX/Si to keep it simple. You then have to extend your secondary O2 sensor wire underneath the car so that it will reach the O2 fitting in the new cat.

You also need to shorten your exhaust pipe by the length of the cat (14", IIRC). Weld flanges on your exhaust to accept the new cat.

 

That's not the way it came from the factory, if this is a USDM 96-00 Civic hatchbox.

If you buy a new exhaust, you'll have to shorten it.

The stock system is manifold with cat, downpipe, exhaust.

You're proposing a header, downpipe, cat, then exhaust.

 

if you do have a cat under your car, you're good to go. the y7 stock cat on manifold is prone to cracking, and the usual (cheap) fix is to replace it with a header and under car cat. i live in the cleveland area, i see you live in ohio. if you're around here, look into rainbow muffler for weld jobs, theyre very cheap.

 

I got a joint down here in Akron that does it cheap, too: Budget Muffler. I am more worried about the O2 sensor being right than anything else. I'll have to put it in the air and look at it before I take it to the muffler shop.

 

An O2 sensor is an O2 sensor - the part is the same between (almost) all 92-00 Civics, and the exception to the rule doesn't apply to your car. The only difference is how long the wires are that come out of it.

 

if you do end up buying a cat, make sure it is actually a cat and not a "test pipe" or resonator. you will not pass with them.

 

Well, I talked to my mechanic buddy and it looks like I'll have to move the cat. Its on the header right now. It seems my flex pipe disappeared and/or my header might be cracked. What do I need to know about moving the O2 sensor? I'm no welder by any means.

 

 

fellow Ohioan! akron huh? im in wadsworth. about 20 min away. you will need to convert to ex style exhaust liked stated above. if you want to put a header on it. and extend 02 wires. do this and your good. look around on the list for civic parts cars. im pretty sure I seen a couple in akron/canton pages.

 

Can I put the O2 sensor in the header or should I move it to the cat? What's the difference?

I ask because I don't know.

 

the primary will go before the cat and the secondary after or in the cat. you will need a ex style cat to run what you want to and still pass echeck.

obd2 system needs both o2 sensors to not trip a cel. primary takes one reading and secondary takes another telling the ecu that a cat is present. cel on at time of echeck for obd2 means immediate fail.

 

theyre called upstream and downstream sensors. you already have both. the upstream (pre cat) sensor will go on the header, and the downstream after the cat. you will need to extend the wires for the downstream sensor. this can be done with some spare wire, solder and heatshrink, or with an aftermarket extension harness. if you want to avoid all welding/labor, buy a 92-00 header, 92-00 OEM fit cat, and a 92-95 HATCH exhaust system. since the eg hatch was already set up for the header/under car cat, the system for it will bolt up to this setup, no fab required.

 

Hey, thanks, everybody! I appreciate all your help in all of this. Now I just have to do it!