Exhaust Headers Options

[Redline08]

If I put stainless steel 4-1 headers on my 99 celica gt, will it still pass inspection? (emission problem?)

[Bigmeanbulldog55]

Completely legally, no. But hell, I haven't been legal for a long time and I'm still driving around. Some places will let you just move the cat, that's what I did.

[jdmart]

offtopic where did u get those headers plus i dont see any problems y u shoudnt pass any test with headers

[alltracman78]

Because the cat is supposed to be as close to the engine as possible to heat up quicker.
And it will effect placement of the O2 sensor.

[Negative]

I have 4-1 with no cat and the 2 o2 sensors are only about 6"s apart. Somehow I still pass and I have never gotten a cel code. I'm OBD-II and Houston's smog tests are a strict as Cali's. I have a magnaflow 3" high flow cat after the b-pipe but that should have no effect on what the ECU sees.
Can't explain it. Every other toyota I have ever put a header on that deletes the primary cat has thrown a code and will not pass legally. IDK - I'm just gonna keep my fingers crossed until next month when I go for my 3rd smog test with the header. Next year will be turbo no matter what so I def will not pass legally.

[LewFX]

i just failed smog, although the egr failed so not sure about header being at fault yet

[jcaron9gt4]

i put some of those headers on my car...i dont know if they're the same ones, you can check out my pics...but i failed...it takes away your cat..Negative, dont know how the hell you passed lol

[Batman722]

i put some of those headers on my car...i dont know if they're the same ones, you can check out my pics...but i failed...it takes away your cat..Negative, dont know how the hell you passed lol

you might have a fed emission Celica with only one cat (the 94s have one, which is gone now because of the header), do you know if you have a second one under the car ?

I have a header for my GT and I have a second cat under the car, but I got my car inspected before I put the header on

[Negative]

Is your second o2 sensor past the second cat on the cat-back part? o0black0o's car was this way but he's ST and I'm trying to figure out why. Seems like it would just be harder to wire that way.
There really is no descent explanation for why I pass? Luck I guess.

[Batman722]

Is your second o2 sensor past the second cat on the cat-back part? o0black0o's car was this way but he's ST and I'm trying to figure out why. Seems like it would just be harder to wire that way.
There really is no descent explanation for why I pass? Luck I guess.

the ST and GT set ups are completely different. As for you passing, well, you have a 99 and still have the second cat (still pretty new and functional). I would guess low miles too...

[Negative]

All true - the second cat is a 3" magnaflow high flow tho - but the way they test here is to let the ECU tell them that there is something wrong with the cat. I.e. there is no cat because the o2 readings are the same on the two o2 sensors. This is why I can't understand why I pass. Why no CEL? It's not a big deal to me, I'm certainly happy that I do and I don't have to bribe someone to pass me but if I could figure out why maybe I could help some of my friends who are in the same sit but don't pass.
Anyone have any learned explanations or ideas?

[kcizzle]

This is exactly the question I was looking for, I just got my 4-1 header and haven't installed it yet. I believe I got the two O2 sensors on the primary cat and I checked straight down and I saw a secondary cat. So if I installed my header and removed the primary cat but still have the secondary one, what are my chances of passing emissions? Has anyone tried having this set-up and take the test? I am from Illinois by the way. Sorry for jacking but appreciate your thoughts.

[Negative]

I think it matters how they test the system and how new your car is. I only know that in Houston they "sniff" the car if it's '95 and older and they use the engine ECU and diagnostics systems if it's 96+. As i said I get lucky and pass even tho they check my diagnostics and somehow I have never thrown a code for the cat. If you look at the engine pic in my profile you will see that this should not be possible. I could understand a little better if they "sniffed" the tailpipe because I have a almost new Magnaflow highflow cat in place of the Secondary cat.
My advice would be to have the header and B-pipe modified such that it mounts and bolts up to the secondary cat just like the stock [but with no cat and better flow obviously]. That way you could very easily switch back and forth for emissions testing with just a jack, 2 stands, a ratchet, 1 socket and an closed ended box wrench. If you lived here I could very easily do it for you. I think it would only be like 8 nuts on a GT. ST is only slightly different if IRC from o0black0o's car.
What states/cities do the testing now adays? It seems everywhere is jumping on this green Nazi wagon. I know:
California
Houston Tx [but not the rest of the state that I know of - I know 20mi from here they don't]

This post has been edited by Negative: Apr 13, 2007 - 8:25 AM

[kcizzle]

I think it matters how they test the system and how new your car is. I only know that in Houston they "sniff" the car if it's '95 and older and they use the engine ECU and diagnostics systems if it's 96+. As i said I get lucky and pass even tho they check my diagnostics and somehow I have never thrown a code for the cat. If you look at the engine pic in my profile you will see that this should not be possible. I could understand a little better if they "sniffed" the tailpipe because I have a almost new Magnaflow highflow cat in place of the Secondary cat.
My advice would be to have the header and B-pipe modified such that it mounts and bolts up to the secondary cat just like the stock [but with no cat and better flow obviously]. That way you could very easily switch back and forth for emissions testing with just a jack, 2 stands, a ratchet, 1 socket and an closed ended box wrench. If you lived here I could very easily do it for you. I think it would only be like 8 nuts on a GT. ST is only slightly different if IRC from o0black0o's car.
What states/cities do the testing now adays? It seems everywhere is jumping on this green Nazi wagon. I know:
California
Houston Tx [but not the rest of the state that I know of - I know 20mi from here they don't]

ok thanx negative, I might just do an emissions test first with the primary cat before installing the header.

[CelicaST_CALI]

y did u ask if the headers will pass after u put them on?lol

[kcizzle]

y did u ask if the headers will pass after u put them on?lol

Because installing the header requires the removal of the primary catalytic converter which is located below the header. Well, the catalytic converter's job is to decrease the level of air pollution that automobiles make, like acting as a filter for exhaust gases. Well, Toyota made the Celica GT w/ 2 catalytic converters, I just wanted to know what the effects will be if the primary cat is removed if I install the header. I got it from e-bay by the way for only $102.00 + $47.00 shipping. I'll post some feedback if I do get it installed whether if I think its worth it or not.

[Bitter]

first of all, stop calling it the primary cat. IT IS NOT! its the warmup cat, the technical term is TWWUC, Three Way Warm Up Catalyst. its primary function is to heat up faster than the main cat and help to eliminate startup emissions until the main cat gets upto operating temperature.

now, if you dont have the sniffer emissions (where the put the probe in your tail pipe) you can use a cheater to get rid of the check engine light so you pass the computer check. you use 2 sparkplug antifoulers in a special way to space the sensor back from the exhaust stream so it gets a smaller sample of gasses and thinks that eveything is fine. you'll want to do that to the sensor that sits below the warmup cat, not the main O2 sensor.

if you DO have the sniffer test you can do 3 things to help ensure a pass
1. use the cheater to get the check engine light to go away so you dont get an automatic fail
2. drive the car around and drive it hard to get the main cat hot, with a good hot main cat you may pass the test.
3. if you dont pass with a good hot stock main cat, get a larger capacity cat welded into place. something intended for a larger V8 should be able to do the trick, and while you're at it you can get it as a highflow cat too!