Can AFR be measured accurately from 2nd O2?

[ahl395]

Strange question that I couldn't find an answer to.

Does anyone know if the 2nd O2 sensor accurately measure AFR or is it too far down the exhaust stream? Planning on using it for AFR based failsafe and would rather not have to get an extra bung welded if I can use the ones already there.

Thanks!

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[80FoxCoupe]

Tuners tuned via a wideband in the tailpipe for decades. I'd assume the 2nd o2 location is fine! I have a new in box AEM wideband failsafe for sale fyi.

 

[Cory S]

Yes, the highest differential of AFR that I have seen from the front the tailpipe, is only .1. You’d have to have a good sized leak somewhere to throw it off.

 

[ahl395]

Thanks guys. Just saved some money on getting an additional O2 bung welded in then. I'm too young to remember cars being tuned via tailpipe but that makes sense I didnt think of that lol.

 

[Grimreaper]

2nd o2 as in the downstream after the cat?

Are your still running cats?

edit: saw your listed as catles with the deletes. the downstream bung would be fine, but the actual sensor usually various in its output/range quite a bit from the upstream sensors.
are you trying to re purpose the rear o2 sensor input? or running a standalone AFR gauge/monitor?

 

[ahl395]

2nd o2 as in the downstream after the cat?

Are your still running cats?

edit: saw your listed as catles with the deletes. the downstream bung would be fine, but the actual sensor usually various in its output/range quite a bit from the upstream sensors.
are you trying to re purpose the rear o2 sensor input? or running a standalone AFR gauge/monitor?

After the cat yes. but I'm catless. Using a standalone AFR monitor just wanted to know if I could use the existing bung or if I needed a new one welded in closer to the head.

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