Quote:
Originally Posted by arghx7
I'm going to make a highly technical argument here that most people are not going to follow. It's an argument based on firsthand experience with Bosch, NGK/NTK, Denso (like the stock FT86 sensor), and actual emission benches.
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You cannot fully trust any wideband to represent actual in-cylinder AFR when the engine is in a scavenging condition. It doesn't matter who made the wideband or where it was placed.
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Great info as always @
arghx7
Makes perfect sense to me. In the same way that a miss-fire will create a lean reading on an 02 sensor because of the lack of combustion, scavenge effect will throw off a reading due to introducing intake charge air into a portion of the exhaust stream.
Most tuners rely on external wideband data though to get in the right ball park, in the same way i have been relying on the factory "wide range" sensor. Knowing how far apart the two readings are, both on average and in specific ranges, is very useful even if it does not give a true in cylinder afr. Once your in a range, you will use power output, knock affinity, etc to arrive at the final fuling.