scootermafia

Hello all. Although my headers are coming today (the generic DC Sports ones) I am rather reluctant to mess with my secondary O2 sensor in order to get them to work. The dealer suggested glibly that I wait until my powertrain warranty expires before putting these on. Common sense dictates that messing with what the secondary O2 sensor senses may be doing things we don't totally understand. Everyone on this board is eager for performance and rips parts off left and right, and I am the same way. Still, I don't trust modifying these components so close to the pair of O2 sensors. Can anyone tell me with confidence that they trust this setup, that there is really no risk? The dealer of course has put on a few headers with copious CEL's abounding. Are you all really wealthy enough that voiding a warranty by accident causes you no fear? I'm 21 and I can afford this car, but not extra repairs on it. I have the right to be paranoid, it's one thing to tune a 10 year old car like a DSM, and it's another to tune a 2007 Scion that has a lot at stake.

I am thinking about adding to my axleback a catless midpipe, as shouldn't it give pretty good, almost similar performance gains by removing that cat in the middle? And no sensors would be able to tell the difference. The stock header is already a fairly nice looking, tubular part with the real problem being the giant cat it contains.

engifineer

To be honest, I dont think most of he companies making headers for the tC actually know enough about header design to properly design them for exhaust pulse and length.. as with many "tuner" companies I think they simply build what they think is closer to equal lentgh and call it good. But all of that is beside the point.

The secondary 02 sensor is used to determine if the CAT is operational. If you do it right, you will trick the ECU into thinking that it is in place and nothing will happen. If you dont do it right, you will have a CEL due to the ECU not seeing a change between 02 sensors, where the CAT should be.

Personally though, with the true minimal gains (Especially when the whole powerband is concerned) that a header will provide you here and the absolute crap they sound like without adding huge resonators, I am not even considering it.

jrodTc

I agree. Save your money and buy a turbo set-up.

maherdan82

As long as you don't mess with the primary o2 sensor you will be fine. The primary o2 in the manifold is for you air fuel ratio. The second o2 is just an ordinary narrow band that lets the computer know the cat is functioning correcly. If you get a header you are removing the primary cat and you will get a check engine light. This will not hurt your engine...just your gas milage due to the computer not going into closed loop. So you won't have adjusting fuel control by the computer, you would run a safe mode set by the manufacturer. But the easy fix would be the spark plug non fauler mod that removes the sensor from the exhaust down stream tricking the computer into thinking the cat is still their.

MeatRocket

I have a 2006 tc, and i have had no problems. i have the dc header, injen cai and greddy sp2 exhaust i put every thing on the day after i purchased it. so far 19,000 miles later i have no issues.Of course my check engine light did come on when i replaced my header . i did the anti-fouler trick on the secondary o2 censor and it did not work. so i drove with the cel on for two weeks and it ran like poop my car would turn off at red lights. so i re checked everything and disconnected the negative terminal on the battery and no more cel. i drive my car hard every day redline at least 3-5 times daily and with no issues . oh and i work for a dealer in sales and your car will still be under warranty.

MileHightC

Good luck getting a powertrain issue warrantied if you've got an exhaust setup that causes multiple CELs or throws your car into limp mode...are you and the 'dealer' you work for willing to provide that in writing?

07tctul

No offense but if your that worried about it don't do it. With modding a car something can always go wrong.

Mid_Life_tC-risis

OK just a little misinfo here. The CEL code you MIGHT get from a properly installed header is a P0420 cat converter inefficiency due to the removed pre-cat. This code is not a primary fault (like breaking your AFR sensor would be) and will not put you in limp mode or open loop. It is usually defeated with the (2) anti-fouler fix, some have needed a third ...

A header will not void your warranty unless the dealer can prove it caused a problem. Frankly, since you're not messing with internals or changing the ECU fuel map I can't see how a header would create any problem that cannot be fixed by simply putting the stocker back on correctly.

Most header install problems are caused by not properly removing the oxygen sensors.

The 4-1 headers (such as DC Sports) show a dyno-proven gain of 7-9 whp which is not bad for the $$, especially if you can get the header used. My DC Sports gave a noticeable oomphh around 3-4K rpm's when I had it on. BUT, as mentioned the rasp is terrible unless you put on a large resonator on the midpipe - that's next on my list

rosedaleny806

not worth it to lose your warranty jus for the minimal gains of the header, i installed mine at 33,000 bc i knew my warranty was already up so watever even though i got no check engine light or anythign at all and all i did was an antifouler, megan header aem intake and megan axleback it sounds nice but not worth losing ur warranty , god forbid sumthing happens engine wise then ur screwed, im planning on trading my 05 for the 08 tc and im jus gonna do the same but im supercharging str8 out of factory=)

DarkSnake

The header is a safe mod, the ecu only really sees the primary o2 sensor. And samples at a slow rate. The after cat sensor was added when the emissions code changed. OBD0 and OBD1 cars do not use a 2nd O2 sensor.

SePaTc

I4 exhaust manifold = header (as in exhaust header)

V engine exhaust manifolds = headers (as in, a pair of manifolds, one for each bank)

fyi. most simple and basic concept in engine modding. thx

MileHightC

Mid-Life,

Agreed...the Magnuson-Moss Warranty Act was designed specifically for using aftermarket (read non-manufacturer) parts on a car (oil filters, oil, air filters, etc.) and preventing a dealership/manufacturer from denying warranty coverage because of use of said parts. So...

If you use a Fram oil filter for your application a dealer cannot deny warranty coverage because of that. K&N filter...same. Non-Toyota windshield washer fluid...same.

You throw on a (and this is where SePaTc and I will agree for the first time) HEADER and a dealer could potentially deny a powertrain warranty since the header isn't a direct replacement for the factory part. They couldn't deny a claim for something like condensation in the lights because you installed a header but the powertrain and electircal systems become fair game. They have to prove the part caused the failure but oftentimes they will either:

A) Deny warranty coverage and let you fight the battle (and they typically have much deeper pockets than the average consumer) or...

B) Warranty the issue and then void any remaining warranty, which means repairs are on you next time or you can fight them (see above).

If you're worried about warranty issues for 7-9 rwhp then don't do it...otherwise let it rip.

SePaTc

imo, 7-9 whp (not Rwhp, milehightc, haha) isn't worth the $$$ or time and effort.

And even if you get it installed and running with no CEL and no warranty issues, then u have to worry about muffling the notorious tc header rasp.

also, 2az-fe only uses vvti on the intake valves, thus exhaust valve timing is constant/static and thus the stock header is most likely the best tuned manifold for the engine in stock trim.

my dc header totally F'd up my afrs, threw a CEL and sounded annoyingly like crap.

MileHightC

Touche man...let's try Fwhp. I like throwing mine on the dyno backwards!

SePaTc

whp will do just fine.

haha, yeah, lets throw a car on the dyno backwards! lol, that dyno will think its the fastest a car has ever gone in reverse! :D