Installing Wideband question?
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St. Jude Donor '12,'13,'15,'16,'17
Installing Wideband question?
Hi,
I have longtubes with the front o2 sensors installed in them and with the Cats removed and rear o2's removed.
My question is, if I install my Wideband o2 sensor in one of the rear o2 holes will it register the AFR's ok?
Thanks for the help!
I have longtubes with the front o2 sensors installed in them and with the Cats removed and rear o2's removed.
My question is, if I install my Wideband o2 sensor in one of the rear o2 holes will it register the AFR's ok?
Thanks for the help!
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Close enough. Assuming there are no exhaust leaks.
Le Mans Master
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From: Greater Detroit Metro MI, when I'm not travelling.
Le Mans Master
Joined: Oct 2007
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From: Greater Detroit Metro MI, when I'm not travelling.
Not an issue here. But yes, if you have cats the O2s should be placed before them.
Melting Slicks
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Melting Slicks
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Yep, it's the absolute worst place to get an accurate reading. One, like I said above, cats produce oxygen and two, taking the reading at the end of the tailpipe introduces outside air, which contains oxygen, skewing the readings even further (leaner reading meaning actual AFR is richer than it shows on the wideband). Back in the "old days" when you took your catalytic converter off, one of the ways to trick the computer into not showing a check engine light was to weld a "spark plug tester" (bung) at the very end of the tailpipe, screw in the rear O2 sensor and extend the wires back to it. The added oxygen content of this rearmost exhaust was enough to satisfy the computer into thinking that there was still a functioning catalytic converter in front of the rear mounted O2 sensor.
Le Mans Master
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They produce oxygen? 
I thought they catalytically combined NO / NO2 with Carbon Monoxide and unburnt Hydrocarbons...
and two, taking the reading at the end of the tailpipe introduces outside air, which contains oxygen, skewing the readings even further (leaner reading meaning actual AFR is richer than it shows on the wideband). Back in the "old days" when you took your catalytic converter off, one of the ways to trick the computer into not showing a check engine light was to weld a "spark plug tester" (bung) at the very end of the tailpipe, screw in the rear O2 sensor and extend the wires back to it. The added oxygen content of this rearmost exhaust was enough to satisfy the computer into thinking that there was still a functioning catalytic converter in front of the rear mounted O2 sensor.
OBD-2 Systems check for the operation of a catalytic converter by varying the air/fuel ratio at idle and part throttle, and then checking that this AFR lags on the post cat O2 sensor. Without the cat in place the two readings are the same and the computer throws a "P0420": Catalyst System Efficiency Below Threshold.
The reason why moving the O2 away from the exhaust stream eliminates the code (sometimes) is because that also makes the readings lag.
Melting Slicks
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OBD-2 Systems check for the operation of a catalytic converter by varying the air/fuel ratio at idle and part throttle, and then checking that this AFR lags on the post cat O2 sensor. Without the cat in place the two readings are the same and the computer throws a "P0420": Catalyst System Efficiency Below Threshold.
I know, that's what I said.
Le Mans Master
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Putting an extension on your O2 sensor does not add oxygen to the system, unless you can't weld and you leave a bunch of gaps in there. The fact that you think it does makes me think you don't really understand how they work... Howstuffworks.com has a great layman explanation.
Melting Slicks
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St. Jude Donor '08-'09-'10-'11
I run a LM1 wideband 24/7 and when I mess around on the dyno, I use the tail mounted dynojet wb. There isnt much difference in the reading and I have cats. Its usually an overstated issue. Its a tenth or so which isnt an issue. Cars dont blow up if they run 13.1:1.
Most LS engines make max power in the 12.3 to 12.8 range. Its likely due to E10 fuel and not having the tune reflect a 14.1:1 stoic.
Most LS engines make max power in the 12.3 to 12.8 range. Its likely due to E10 fuel and not having the tune reflect a 14.1:1 stoic.
