How can I tell if my A/F Sensor in stock manifold is going bad? My logs shows it rearing normally 14.7... But car is running crappy...
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Double check the readings with a wideband or swap it out with a friend's sensor.
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What do you mean by "running crappy"?
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Log the rear O2 sensor voltage while running steady-state with some load on the engine (like highway cruise). If the rear O2 is pegged (rich or lean) and the front AFR is showing stoich, there's a good chance one of them is borked up.
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