O2 sensor on headers

[91Subbed]

I just installed long tube headers on my 1991 suburban 350 2wd, I was wondering what to do with the o2 sensor? Ive heard use the stock single wire one in the header collector or put it on tube #4 or #8. I've heard use a 3 wire sensor. Any help with this problem? Thanks!
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[68Timber]

I didn't know those needed to be tricked. You can't just add a bung to one collector and reuse the original o2 sensor?

[91Subbed]

That's what I'm hoping to do, but the research said its ideal to go with a 3wire o2 sensor. Idk that's why I'm trying to get any input I can. Thanks for the response!
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[Rogue_Alphonse]

Just weld the nut all the way down by where the collector bolts to the exhaust and extend the wire [wrap it with something heat resistant too!] I did it with a new o2 and it works fine!

[cal30_sniper]

Originally Posted by Rogue_Alphonse

Just weld the nut all the way down by where the collector bolts to the exhaust and extend the wire [wrap it with something heat resistant too!] I did it with a new o2 and it works fine!

x2

No need for a three wire heated O2 sensor unless your vehicle originally came with one.

-cal30sniper

[Mike Nixon]

I put an H pipe in the exhaust just past the collectors and install the 02 there if possible. it draws off both banks then and monitors the entire engine.

if you can't do this then just put a bung in the collector and go on. The single wire unit is a good unit for the app they're used in.

[cal30_sniper]

The problem with the H-pipe O2 sensor is that your readings are very far removed from what the engine is actually experiencing. There's a time delay for the exhaust to get there, especially considering that you're going to have mixing and stagnation inside the crossover. Heat within the crossover is also much less than the collectors, which could screw up the readings (both actual composition of the exhaust, and what the sensor actually reads).

I would not advise putting the sensor in the crossover. Not saying it won't work, but it's definitely not ideal. The factory sensor only reads one bank, because it is placed as close as possible to the cylinder exit that can still get an averaged bank reading. That is for reasons of both temperature and response time.

[Mike Nixon]

Originally Posted by cal30_sniper

The problem with the H-pipe O2 sensor is that your readings are very far removed from what the engine is actually experiencing. There's a time delay for the exhaust to get there, especially considering that you're going to have mixing and stagnation inside the crossover. Heat within the crossover is also much less than the collectors, which could screw up the readings (both actual composition of the exhaust, and what the sensor actually reads).

I would not advise putting the sensor in the crossover. Not saying it won't work, but it's definitely not ideal. The factory sensor only reads one bank, because it is placed as close as possible to the cylinder exit that can still get an averaged bank reading. That is for reasons of both temperature and response time.

In theory this is true, and I run the H as close to the collectors as possible. That being said, on my 94 2500 2500 HD with a TBI350, 4L80E, and 4:10 gears, I picked up 2 mpg fuel economy gain with this mod and a true dual exhaust system with hi flow convertors. Readings on the scanner did not change a bit, and the activate time on the O2 from dead cold was the same. It does not drop out of closed loop after the initial warm up. The relocation of this sensor is about 12" farther back than it was in the OE location.