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There has been a lot of cars I have tuned lately that have added o2 bungs to there headers or down pipes for the front o2 or the wide band

It is VERY important that the bung is 1/4 - 3/8 thick any more then this and the o2 sensor does not go far enough into the stream to get an accurate reading

This causes bad reading for the stock fuel trims and the wide band throwing off the reading a good bit

There also seems to be a short sensor (the part that goes into the exh stream) that is being sold watch for this if you change the o2 sensor

Tom
 

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Hatch Nation #136
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Good advice. I'll be doing my header soon, and I'd like to avoid false starts.
 

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Tom how did you figure out the problem?

I think mine are setup good?



 

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Check those welds for leaks too.

Install the o2 sensor and verify the sensor is fully in the exhaust stream. A bung that is too tall will hide part of the sensor.

I bought a cheap bung on eBay that was well over 1/2" thick which I could easily tell wouldn't let the sensor sit far enough into the exhaust stream. Cut it in half, no issues and verified sensor has full engagement in the exhaust stream.
 

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Sonic Mk3 Crew #03
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There has been a lot of cars I have tuned lately that have added o2 bungs to there headers or down pipes for the front o2 or the wide band

It is VERY important that the bung is 1/4 - 3/8 thick any more then this and the o2 sensor does not go far enough into the stream to get an accurate reading

This causes bad reading for the stock fuel trims and the wide band throwing off the reading a good bit

There also seems to be a short sensor (the part that goes into the exh stream) that is being sold watch for this if you change the o2 sensor

Tom
HAHAH Yep Im one of them! As soon as I put the o2 in a proper spot and a proper bung the car no longer stumbled at idle and drove properly at 2000 or less rpm without power loss.

Be careful anything larger then .375 is pushing it.

World of a difference. Toms the man with the most patience I swear because I was ready to pull my hair out!
 

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good info. i got the lc-1 you said i needed. the bung is 1 1/26 tall. when we grind the curve into it for the header we was thinking it would make it 9/16 tall. so nee to cut it down a lot i guess.
 

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Good info, was wondering about this as I was about to weld in a 1/2" Innovate bung into a HFC. Here's a couple pics of a less thick Innovate bung in my stock SVT cat for reference. I assume this is the way its suppose to be done?





 

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Its hard to tell by the picture but both of those look very thick/tall

Tom
Well so far mine is running pretty good i think for what ive done. I do notice a little surging but i just removed my tumble flaps so im not sure how its supose to act now.

In the pictures i posted, the better looking one is the stock OBX welded bung from the factory. I have the stock OEM 02 sensor in that one. The one with the shitty weld job has the wideband in it. That bung came with my AEM wideband and it has a beveled edge i made sure i drilled it so the bevel fit down into the pipe.

Mine looked like this with my AEM wideband, and i drilled the hole so it fit into the header up to the red line. I think mine is in deep enough, i could be wrong though.


I had my exhaust installed about a month after i put the header on and they checked it for leaks and it was ok.

Should i take it into the muffler shop and have them grind the bung down lower?

Since im not running a cat now, i can take it into a shop that has a wideband that mounts to the tailpipe and it should read the same right?
 

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Guessing this is too long then?
 

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I'll put this on my list of things to do.
 

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Amazing that this hasn't come up before... GLad it was now.
 

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Could someone tell me the size of the socket needed to take out the o2 sensor on a stock 2000 DOHC Zetec exhaust? I'm trying to find a socket for the one near the manifold.

Thanks, and good info Tom, it will be useful when I get my SVT set-up.
 

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I <3 my SVT
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I am not at the exhaust shop getting this done, after big headaches with tuning.

Matt
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