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Running lean in CL.

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Old Aug 8, 2014 | 12:37 PM
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Default Running lean in CL.

My wideband shows pretty much perfect in an open loop idle...mid 14's. A soon as the ecm hits closed loop, the afr jumps up to mid 15's - low 16's, with a commanded 14.6. That would be an o2 issue, correct?

The o2's read .200-300mv range most of the time, they do switch...but slowly. However, the efi live log shows an average of around .500mv.

Thanks guys.

Rob
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Old Aug 8, 2014 | 12:41 PM
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Car modifications? Tuned?
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Old Aug 8, 2014 | 02:15 PM
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Originally Posted by idle
Car modifications? Tuned?

346, ported 5.3's, cam duration is 234/240 - 13 degrees of overlap I believe, FAST 78, stock tb, and TSP 17/8's to a Spintec super pro street. I was originally getting a B1S1 o2 slow response code with pacesetter 1 3/4's...now it's throwing for both banks with the 1 7/8's.
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Old Aug 8, 2014 | 02:22 PM
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If you've got O2 related codes then closed loop fueling
is untrustworthy. Although the usual outcome is to trim
rich.

You can push things around a little (or a lot) by altering
the O2 switching threshold vs airflow mode (and maybe
want to alter the mode-bin vs airflow mapping, as well).
Going from 500mV (truck) to 350mV (F-body) moved
idle wideband AFR reading down by a whole point on one
truck I was messing with. But if your O2 sensors are
not right and tight, maybe not worth messing.
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Old Aug 9, 2014 | 09:17 AM
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Originally Posted by jimmyblue
If you've got O2 related codes then closed loop fueling
is untrustworthy. Although the usual outcome is to trim
rich.

You can push things around a little (or a lot) by altering
the O2 switching threshold vs airflow mode (and maybe
want to alter the mode-bin vs airflow mapping, as well).
Going from 500mV (truck) to 350mV (F-body) moved
idle wideband AFR reading down by a whole point on one
truck I was messing with. But if your O2 sensors are
not right and tight, maybe not worth messing.
I appreciate the input. My o2 threshold is already at .450mv. Should I try lowering it even more?
I think maybe I need to get under the car and check for leaks around the y-pipe/header connections.
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