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94' toyota corolla d
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Discussion Starter #1
I'm a bit confused if my car is California emissions or fed/can emission. theres no sticker i can find anywhere on the car stating this. Theres is a pre cat on the exhaust manifold with an 02 sensor and then theres and 02 sensor before the main cat. I'm confused as heck... shouldnt' the 02 sensor be after the main cat?

I know my corolla was build in October of 94' in Canada from looking up the vin. I'm only asking this question due to a cracked header and leaking flex pipe that i need to replace. Any info would be awesome.

-Thanks
 

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1994 Corolla DX
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4,422 Posts
Pre cat = Cali emissions. You should have a hood sticker that indicates this?

Also you can use a vin decoder at any OEM parts website to verify. Like toyotapartsdeal.com
 

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Porsche
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I'm a bit confused if my car is California emissions or fed/can emission. theres no sticker i can find anywhere on the car stating this. Theres is a pre cat on the exhaust manifold with an 02 sensor and then theres and 02 sensor before the main cat. I'm confused as heck... shouldnt' the 02 sensor be after the main cat?
Take a photo of your exhaust manifold and preconverter to post here.

The main catalytic is actually the preconverter as it's about twice as large as the downstream secondary cat. That's why there's O2 sensors before and after it.

Do you also have EGR?
 

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94' toyota corolla d
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Discussion Starter #7
I'm sure it's tough to see cause its from a phone but this is the 02 sensor AFTER the flex pipe and Before the 2nd cat

I know Cali emission corollas sometimes have different throttle body's too.

And this is the whole engine.
 

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94' toyota corolla d
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Discussion Starter #9
i was thinking about going with these after market chrome 4-2-1 headers witch means i'd have to get rid of that pre cat. that wouldn't throw a check engine light or an emission failure for federal emission?
 

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i was thinking about going with these after market chrome 4-2-1 headers witch means i'd have to get rid of that pre cat. that wouldn't throw a check engine light or an emission failure for federal emission?
Funny you talk about putting a header in your car, I just installed one in my Cali emissions car.

Few things to keep in mind with the header.

You will need BOTH O2 sensors replaced with the screw in type.

The header is too short for the Cali secondary cat, it's about 4 inches too short.
What I did is I cut the flange off the header and welded in a piece from the old down pipe.


The new down pipe hits on the cross member and rattles, I have not tackled this yet but others have.

You will need to add a secondary O2 sensor bung and bypasser, which is 2 spark plug non foulers screwed together, I have not done this yet.

I just found out it will throw a CEL with the secondary O2 unplugged, it took my car 80 miles to figure it out.
 

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1997 Corolla
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Is this a tear in your air inlet tube, seen under the clamp?


Dunno if that would really upset the engine, computerwise, but if the tear protrudes past the throttle body, and allows false unfiltered air into the engine, it certainly can't be good.
This is when you're glad these cars aren't Mass Air, because the false air would really upset the computer - kinda like an exhaust leak before the O2 sensor...
 

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94' toyota corolla d
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Discussion Starter #13
Yes it's a small tear but it doesn't go past the clamp. no problems yet but i am going to dress the situation sooner than later.
 

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Leaks also throws off MAP-sensors, just not as badly as AFM/MAF. Here's how I adapted the headers to my CA car. I went with flange-type O2-sensor because that's what the car came with, and they're easier to install and remove.



I eventually replaced that small downstream cat with a larger 2.5" unit so I could pass CA smog tests without the preconverter.



Also tapped the hanger tab so it would work with the factory 8mm bolts. Easier to install as you don't have to juggle two wrenches overhead while on your back.

 

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94' toyota corolla d
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Discussion Starter #15



Nice! that's what i need to do. did you buy or make that adapter for the 02 bung? looks rad though!
 

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I cut a flange from 1/8" plate and welded it to the adapter pipe. Then drilled holes and tapped for 8x1.25mm studs.

Note that the end of the downpipe section is about 1" lower than stock on my 1.8L 7A-FE and it rubs on the crossmember slightly. I wrapped that section in a silicon kitchen mat so it doesn't rattle and wear through the tubing. At some point, i'll chop the downpipe tubing from the 2-hole flange, cut off 1" and re-weld it back onto the flange.
 

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Discussion Starter #17
looks really good to be honest. Here's the question though, I'm sure everybody who's thinking of buying this type of header is wondering...Is it worth it? does it give you any hp gain? I know the 7a isn't a high performance engine but I'm just curious before i go and drop $100 on em.
 

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1997 Corolla CE
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I'm going to warn you, an ebay header will fit like crap and need work to make it fit properly. I thought I would save some money buy getting an ebay header to replace the cracked exhaust manifold that was in my car. Issues I ran into: The holes that mount the header to the engine block needed widened slightly, the O2 bung needed relocated (had a muffler shop do it), the cat didn't bolt to the downpipe (I cut off the excess from the downpipe, bent the minor portion I couldn't inwards so it would slide into the cat), and the down pip rubbed on the crossmember. I had a muffler shop fix that issue. I have a 1.6l with a 3spd auto for reference, but others have installed ebay headers and have reported similar issues.

Here's a good DIY greentrees2 made

http://www.toyotanation.com/forum/1...86098-ebay-header-1-6-diy-install-review.html
 

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I think I have the same CA emission engine also, judging by what anthony posted, my engine has TWO O2 sensors in the same place and has an EGR valve and my exhaust is as loud as a boom box, lucky i didn't bought the fed emission exhaust yet.
 

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looks really good to be honest. Here's the question though, I'm sure everybody who's thinking of buying this type of header is wondering...Is it worth it? does it give you any hp gain? I know the 7a isn't a high performance engine but I'm just curious before i go and drop $100 on em.
It gives some minor gains. A better option is a 4-1 Pacesetter header with a merge collector and true equal-length tubes. Would yield 2-3x the HP gains as the popular eBay style 4-2-1 headers. Those don't have equal-length tubing and the diameter is too large for the air-flow volume generated by these engines.
 
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