70 dart 470 ci drag car build.

MOPARMAGA said

I should have remembered to post that both afrs worked the last couple pulls.
You make some points that made me think.
We have a 6inch exhaust system that lays on the ground with big semi tractor mufflers on the end.
There's so much exhaust pulse reversion coming back out of that pipe that's hooked to my collectors so there's air definitely getting backed up and the point of the 02 sensor

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In my opinion the reversion at low speed can sometimes make the o2 reading unreliable. I don’t know that as fact. This can be affected by the length of pipe behind the o2 sensor too. I see lean spikes in the o2 curve at lower rpms that don't coincide with the air fuel ratio as calculated by the airflow and fuel flow meters. There could also be others reasons for that too.
All that said about how unreliable o2s can be I have found them to be very helpful (a real time saver) and for the majority of the time a reliable indicator of the air fuel ratio.