Reflashing the trucks computer after Cat/ Emission Delete

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Eman85

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I don't know why you'd have pipes with no bung for the 4th O2 sensor. I have a 97 Tahoe, 99 Yukon and 98 K2500 and they all have 4 sensors. My K2500 had the cats removed and the PCM was never reflashed and never sets any codes. I would just have the bung welded in and see what happens. I question how the spark plug antifoulers are any type of real fix, need to see the theory.
If I were you and did pull the PCM to eliminate the downstream O2 sensor setting codes I'd also have the security system disabled.
 

east302

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I don't know why you'd have pipes with no bung for the 4th O2 sensor. I have a 97 Tahoe, 99 Yukon and 98 K2500 and they all have 4 sensors. My K2500 had the cats removed and the PCM was never reflashed and never sets any codes. I would just have the bung welded in and see what happens. I question how the spark plug antifoulers are any type of real fix, need to see the theory.
If I were you and did pull the PCM to eliminate the downstream O2 sensor setting codes I'd also have the security system disabled.
On mine, the fourth sensor is on the muffler-side of the flange and not on the y-pipe. Seems like it should still be there is that part is still stock?

7806F486-9135-4969-86E0-1DC68D63E1E6.jpeg
 

east302

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Did you keep the section downstream of the flange (what I posted) that goes to the muffler? On the stock part, the fourth sensor bung is in that section and not in the y-pipe section.

Your part looks to be correct.

An aftermarket exhaust is pictured below, but it matches stock. The converters with y-pipe are to the left, fourth O2 sensor is on the right of the flange:

0DD8A73E-4FF0-4F16-8DBE-E6F523CF3EB0.jpeg
 
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IRQVET

IRQVET

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So the issue I’m having is the 4th o2 sensor is right below the drivers side door, and the lead/wire is maybe 10 inches. Minewhile, the left side of that pipe listed above drops down and cuts steeply toward the passenger side. So the pipe is literally 2 feet from the o2 sensor that is 14 inches short of being able to stretch that far.

For a crude visual, my o2 sensor is about where the left page arrow is on the screenshot. My o2 sensor is nowhere near the flange like yours is . . .
 
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east302

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The y-pipe is dropped down for a head replacement, but the driver upstream sensor is shown below. It looks to be in about the same place as the upper left one in your catalog photo. Is that the one you cannot get the wiring to?

I meant to ask, are you doing true duals on it? I’ve done my 98 trucks since there’s room, but can’t quite figure out the routing to make it work on my two-door.

4C5D26D3-EE7D-4CAA-8E32-FEA7B420049D.jpeg
145A47C1-B193-4D22-87D7-EE66F6E1F2FB.jpeg
 
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No not true duals, two into one. I wanted to keep my exhaust as stock (looking) as possible. I’ll take some better pics this week so you have a better idea what I’m looking at. Appreciate it East302 with all the pics your providing, its nice to see what other folks sets up look like.
 

east302

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Not a problem. Those pictures are of my son’s truck (98 ex-cab) with a Walker setup, but it’s the same as my Tahoe.

Your Jegs pipes look correct in the catalog, so it seems like it should bolt right on.

Catch up later, maybe it’s something simple or they sent you the wrong part :)
 

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