Quote:
Originally Posted by JANNETTYRACING
Looking at the Dyno Graph AFR, I don't believe the AFR Reading is Accurate.
First it starts at 19:1 then goes Flat at 12.6 or so, I very Much suspect a Bad O2 sensor.
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Hope this info Helps.
Ted.
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Actually that's what it looks like when someone shallowly tailpipes the wideband sensor on the dyno. At light throttle, it's completely polluted from outside air. At WOT, the positive pressure in the pipe evacuates all of that and you see mixture with some transport delay. I tune with my own gear up front but often run the tail pipe unit just because it's there on the dyno. You can see how it can be polluted like this as well... every tiny opening along the way is subject to the venturi effect when there is a high volume of exhaust gas moving at a high rate through the piping. You get an artificially lean reading in these cases (to varying degrees obviously) from the tailpipe unit, even at WOT where it appears to work somewhat correctly.