newguyincarworl

Manifild has a crack right next to 02 sensor and i was told to buy a new one online cuz it would be cheaper. A coworker told to get a 4-2-1 header. I was goin to do it but noticed that i would have to remove my catalityc converter and have to live with the engine liggt on. Do i need to have the cataliryc and 02 sensors? is it bad if i dont?
Should i just buy the 4-2-1 header or look for a stock manifold?
Dont really know muxh about cars and wanted to know what other people thought

99 Civic Lx

$60 Header (1999 Honda Civic Bolton Premiere Headers) (Part # REPH961301)

rustycivic

Stay away from cheap no-name headers. A quality one will have a port for the O2 sensor. I'm guessing your Civic is the one that has the cat right attached to the manifold. You can buy a new cat, and have it welded on under the car after the header.

DC Sports and Pacesetter make decent quality headers that aren't too expensive.

Poopies

iTrader: (4)

Header= exhaust manifold

Legally, yes you do need a catalytic converter... especially if you have to go through emissions testing in your state. It helps reduce harmful emissions into the atmosphere. The upstream (header-mounted) O2 sensor allows your engine to make adjustments to run more efficiently. *Definitely Important!* The downstream sensor (located behind the cat) is used to measure the efficiency of the cat system, and to my knowledge is only really used by emissions testers.

Your LX has the converter attached to the exhaust header so unfortunately it'll be a more expensive part to replace. If you were planning on upgrading your exhaust anyway, you could change to the EX system (which has your catalytic converter located under the vehicle after the header). This would give you a better choice on exhaust manifolds.

I would not recommend driving without a cat. Just my .02

newguyincarworl

I was looking at the picture of the header and it looks like it has two possible spots for the o2 sensor. One on each pipe.


So would I order a header that says its for 1999 Civic EX and add my LX cat to the end of it? or do i buy a new EX cat as well?

newguyincarworl

What do you guys think about me buying the header and getting O2 extenders / defoulers?
Bad idea?

got it from here
https://www.civicforums.com/forums/2...t-diy-faq.html

Poopies

iTrader: (4)

If it has two sensor ports on it, that should work! Here's an example of a Magnaflow one: http://www.carid.com/1999-honda-civi...r-3620074.html

Here's an EX-type catalytic: http://crazyboyauto.com/magnaflow-19...nverter-22630/

You would have to get a new cat as well. Yours is attached to the header. If you were already suspecting it is bad, then replacing both may not be such a huge deal. Here's an awesome, high-budget diagram to help you see the difference:



Well, those are supposed to negate the use of a cat by making the computer think that the exhaust is cleaner than it really is. This is because the 02 sensor is placed farther from the exhaust itself. This is ILLEGAL, and also kind of irresponsible, although it could save you some dough. Since Civics already aren't too hard on the atmosphere (compared to other autos), it's obviously up to you. Here's a post from a guy who did it: https://www.civicforums.com/forums/2...on-w-pics.html

I personally wouldn't do that, although I would consider getting the high-flow cat for a potential performance gain. If my existing converter went out, that is.

aircooledjames

iTrader: (2)

Pacesetter is terrible. You get what you pay for in that case. If you go aftermarket there are plenty of decent cat/manifold combos on amazon. I replaced mine with a magnaflow and it was great. Actually better quality than oem. Also check Rockauto they have really good prices.

aircooledjames

iTrader: (2)

Don't do it, defoulers only work a third of the time. I did it and with a catless header got the defouler that went straight out (vs 90 degree defouler). It ended up grounding the secondary 02 sensor wire and permanently frying my ECU(had to replace later). Also driving without a cat smells like ****. You will dread starting your car. If you go the cat weld technique that would be cool, but in the long run it's really not worth the time and effort.