7A-FE Header, Confirmation on thoughts needed Options

[Box]

I'm trying to figure out what to do exhaust wise. Had taken the heat shield off to paint it, and found 3 cracks in the exhaust manifold. None of them are all the way through yet, but figure it's just a matter of time at this point. Of course all of the headers available for the 7A-FE throw everything off: upstream O2 sensor doesn't read off all 4 cylinders, removes the catalytic converter below the manifold and then would throw off the downstream O2 sensor reading. Only other option would be to get another cast iron manifold. Then again could probably get a 7A-FE header then modify it into a 4-1 coupler and put the O2 sensor port on the coupler. That way could maintain the rest of the exhaust and not worry about throwing codes. Though from what I've read by searching on here, being it's OBD-I removing the cat between the sensors shouldn't throw a code. Being this is Alabama, emissions testing is not a concern. My concern is throwing the computer off, and hindering performance/economy instead of helping it. The cheapest cast iron manifold I've found is $90.86 shipped, where as I can get the header and down pipe for $58.90 shipped. Not only that but I get money from scrapping two cats by going the header route. So you can see my dilemma at hand. Another thought I had would be to remove and patch the O2 sensor port off the header and put the port on the down pipe, connect the secondary cat to the end of the down pipe and relocate the downstream O2 sensor behind that cat. Thereby emulating the current factory setup. If anyone could shed some light on this it'd be greatly appreciated.

[6gcpr]

I have a header installed on my 7afe corolla and it didn't throw any codes. If anything it helped performance and fuel economy. And just for kicks i removed the cat because it was veryy clogged up. My header is from obx. Had the pipes made 2 1/4 inches all the way to the muffler. As well. This setup helped my short ram air intake greatly the car sounds wonderful, best of all, it passed the emissions test with flying colors.

[celica74]

the obx header and down pipe doesnt have the downstream o2 bung. also, its 2 inches shorted then the stock one. it took my 94 2 years to set a cel for the downstream o2 not being connected. havent seen any problems with the upstream o2 only reading the one cyl. performance wise i think it helped, gas mileage i never paid attention too.

[Box]

That was another thing, if I go with a header will be going ahead and redoing all the exhaust too. I just wish they made a header that'd work with the OEM setup. Need to call my local exhaust shop to see what all they do. I don't think they make headers, doesn't hurt to ask though I guess.

[6gcpr]

Have you checked the ceramic headers pacesetters make for the 7afe?

[Box]

I think I've looked into them at one point, will have to look again.

[toyota123]

Box if you are worried about the second O2 sensor this is what I just did to my wife's 7a corolla.
$80 eBay header and down pipe (was a bitch to install because it wasn't drilled or bent right and was way to close to the AC lines) a Weapon R intake magnaflow high flow cat and a cat delete/resonator I found on eBay that I thought was a cat because I miss read Tue listing. I ended up having to go to a muffler shop after I got the headers and down installed.to have them weld the exhaust cause I could get it to line up.Long story short her car is much happier now. It sounds much more aggressive and I don't have any dyno to back it up but it feels like another 50+ hp added btw hers is a 93 so OBD1 also and no codes the resonator tube has 2 spots where you can plug in an O2 sensor her car only has one so I just plugged it

This post has been edited by toyota123: Aug 23, 2012 - 9:43 AM

[6gcpr]

That's exactly how i felt with my setup. Car sounds more aggressive, more loose and faster. And not to mention more fuel economy.

[Box]

What I'll end up doing I suppose once the manifold finally cracks through. I'll plug the O2 sensor port on the header, and put one at the soonest point where I can get a read off all 4 cylinders. At least that way the reading between the upstream and downstream sensor will be the same. Then lots of straight pipe, and a muffler.