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i installed an after market headder from MVPmotorsports.com to replace a $1700 oem part. i like the look and can post pics, i like the minor power gain how ever it deleted the cat and the 3rd O2 censor is giving me a check engine light i would like to try to get the code ignored by the computer but simply resetting the computer just brings back the code 10 min later. I would like to find a more perminit solution i would love some input, im kinda at a loss. I purchessed an O2 bypass that looks like an extention however it only works for screw in O2 censor however the 3rd O2 censor is a flange type and the vender didnt support that censor type

plz help me ... the CEL is driving me nuts .. and i dont wanna drive with black tape over the light anymore

the screw in O2 bypass i found at http://bigdaddiesgarage.com/straight-cel-fix.html the OEM 3rd censor is flanged so it didn't not work.

deathsled

you can purchase an o2 simulator and wire it in in place of the 3rd sensor, or you can have a custom flange type spacer made to do same kind of job as the screw in type

Batiatus

I have these headers installed and have never had a CEL. I wonder if its something else causing it. Maybe one of the O2 sensors got messed up during installation. What year is the car?

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Its a 1997non vvti and the censor went off after driving 10 miles when the car heats up. Toyota told me the error was from unbalanced Exhaust to the 3rd o2 censor from not having a cat

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i asked the ppl at autozone and had them pull the check engine codes and i got 2 codes

P0420 - witch autozone was confirming that is the deleted cat haunting me from the grave

P0401 - autozone didnt even know what it was nor could find a cause

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further review i found

P0401 is associated with the EGR valve or the EGR VSV

however i could not find a part number or site with a replacement ... im just starting to do my own auto work and still don't have a full grasp of what i need to do i still need help with the

P0420 zero cat (some kind of a bypass or computer that can completely ignore this code)

local exhaust shops want to charge me $700 to play musical chairs with my pipping and install a cat (i dont want to do this if possible)

this all started with a simple exhaust leak that is snowballing into full custom exhaust .. i want to do a full conversion however the funds aren't there yet so im just trying to get by with working with no CEL's

INTIMAZY

iTrader: (5)

Have you the non-fouler trick?

Worked wonders on my longtube'd racecar.

edit: Just saw that its a flange. Nevermind then.

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I'm afraid I don't know what that is

Batiatus

I'd see about getting the code P0401 fixed first, it might even get rid of the other code. I'm still not sure the aftermarket headers are causing the other code. I'd say its a bad O2 sensor or a bad gasket leak if you get the vacuum code fixed and it still shows up. I've got a 96 so its the same sensors and never thrown a code for the MVP headers.

Messing with the vacuum system, for me at least, is a pain so I won't be much help there. It could even be from a hose not connected or cracked, or a blocked one. If you look under your hood though there should be a diagram of the system.

This thread is old but still has links to good parts stores https://www.clublexus.com/forums/per...s-dealers.html look up under emission system parts.

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im looking into the vacuum issue ... but i remember getting the egr valve code long before i got the header installed but every person i talk to with a P0420 told me it was from deleting the cat and bypassing the 3rd O2 censor will fix it ... i just reset the egr valve code and it just makes it way back if i run the engine cold (i also got a bad heater control valve that i have been manually switching every season however i dont think these issues are connected)

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well ive been doing some poking around on the internet and found a few sites and had a few ideas

http://www.ubertechnics.com/O2_Simulator_2.5.aspx <-- O2 sim

http://www.tokensolutions.net/produc...simulator.html <--- O2 sim

http://www.tokensolutions.net/produc...KIV-Supra.html <--- not sure it works for my car

http://www.streettunedmotorsports.com/parts/o2_bung.htm <--- and just weld in a screw port for the existing mod i already purchased and switch the O2 censor from flange to screw

anyone had experience with any of these?

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well 2 years have passed and i have the same header and had to rebuild the whole mid-pipe .. but ever since i got rid of the OEM pre-cat header and switched to the MVP Motorsport header I've had nothing but check engine lights, since then ive spent over 3k trying to solve it. I've replaced the EGR, MAF, a full vacuum flush, even a new Cat, and replaced all 3 O2 censors (everything from the motor block to the back axle is all new metal) and still no luck. Any suggestions?

Candela

iTrader: (1)

SO youre saying that youre midpipe has no cat anymore? Thus, the car has zero cats now? You found a way to attach the rear/3rd o2 sensor via a flange or thread, and now you still have a CEL?

You have to use the non-foulers (those extenders that were mentioned previously) for the rear/3rd o2 sensor. That o2 sensor is supposed to read "less" pollution because that o2 sensor comes "after" the cat. By placing that non-fouler/extender, it will read "less" of the exhaust flow, therefore tricking the system into thinking there is a cat.

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only the pre cat from the OEM header was removed due to the install of the MVP header .. the cat in the mid pipe is brand new (recently replaced) and the 3rd o2 censor is in this stock location and was replaced with the mid pipe but is still a flange type o2 censor

basicly the whole mid pipe was completly reconstructed to OEM specs .. the original had more holes then swiss cheese

Candela

iTrader: (1)

I think you should still place the extender on the 3rd o2, because it is still expecting to read 'less' pollution, since there are technically 2 cats before it, and now you only have 1 cat before it.