I've always heard that the best way to get an accurate O2 reading while tuning required the addition of 2 O2 bungs up near the x-pipe or just after the headers. I know some tuners simply use the tailpipe O2 sniffer for their tunes.

How accurate is each method? What's the variance typically between the two readings?

Lastly, what method do you employ when dyno tuning?

Again, I've always thought the O2 bung is the best most accurate approach but maybe it's not all that "off" to use the simpler tailpipe sniffer. I'd appreciate the tuners collective input on this - think it would be good topic of discussion to get the big tuners opinion on this. Thanks!

We've always used the tailpipe sniffer for our wideband on the dyno when we tune. As long as it is inserted properly and doesnt blow out during the run the readings are fine. Our dyno shop has done thousands of cars this way and never had a problem. If you are street monitoring then you would want to install 02 bungs to hold the sensors in place.

We've always used the tailpipe sniffer for our wideband on the dyno when we tune. As long as it is inserted properly and doesnt blow out during the run the readings are fine. Our dyno shop has done thousands of cars this way and never had a problem. If you are street monitoring then you would want to install 02 bungs to hold the sensors in place.


This might be a dumb question, but is it possible to run lean on one bank and rich on another bank? If so, how could you tell using either a single bung or single tailpipe sniffer?

Assuming the spark plugs and injectors were all working properly, is it even possible to have different O2 measurements from one bank v. the other bank? I was kinda thinking that unless you had a bad injector or spark plug, the ECU isn't necessarily giving unique signals to each injector. Or is it?

Our cars have 2 front 02 sensors one for each bank so while it is possible to monitor and tune each bank our engines are so symetrical and the fact that the exhaust from both sides mixes in the middle of the car before exiting that it isn't necessary at power levels currently achieved to bother with specific tuning for each side.

The 3800 V6 motors we work on which have made almost 1000 horsepower only had 1 02 sensor for fueling and while we were able to make some improvements using cylinder skewing on those we did so more to control detonation in the hot cylinders like the rear middle (adding some extra fuel for cooling) than to tune it for a specific AFR.

If you were doing a custom intake where one side was a longer or shorter than the other then you may want to make modifications by bank or cylinder in that case.

You'll have to verify that on a G8 it's in open loop for WOT operation for my method to work.

On my ford I unscrew the drivers side upstream 02, leave it plugged in, and use some wire to hold it up and out of road wash. Then I screw in my wideband sensor for tuning purposes.

Again, I don't know about how a G8 would use the stock sensor at WOT. On my ford it's not used in that situation and makes for a perfect and cheap way to tune.

Rich