Wide band 02 sensor placement-before or after the cat?
07-27-2005, 10:20 AM
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Wide band 02 sensor placement-before or after the cat? Does anyone have a definite answer as to the difference in Wide band AFR readings before and after a cat. The several tuners I have talked too said at WOT it makes little to no difference. Has ahyone seen otherwise? Thanks!
07-27-2005, 10:27 AM
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For tuning, it's probably best to position it close to the engine, before the cat, in a collector.
If turboed, probably 6"-8" after the turbo.
They don't like to be too hot, so they don't need to be right near the exhaust port like an egt probe.
If turboed, probably 6"-8" after the turbo.
They don't like to be too hot, so they don't need to be right near the exhaust port like an egt probe.
07-27-2005, 10:28 AM
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depending on the vehicle and cats, at wot once the oxygen is out of the cats, there is minimal difference.
I did some testing with 2 good widebands (AFM1000 units) and after about a second or 2 at wot, they were nearly identical readings. This was on a 2004 F150 5.4 3Valve with huge 3 brick cats.
Ryan
I did some testing with 2 good widebands (AFM1000 units) and after about a second or 2 at wot, they were nearly identical readings. This was on a 2004 F150 5.4 3Valve with huge 3 brick cats.
Ryan
07-27-2005, 11:16 AM
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I was going to install the WideBand 02 after my cats. I have no rear 02's as I turned them off with edit-so I have to open ports there. I just wnated to make sure that most people get the same readings before and after the cat at wot. If there is a difference I have heard .2 at the most.
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07-27-2005, 12:17 PM
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There will be some "smoothing" from the chemical
goings-on, not much at WOT as airflow is large
but if you want reasonable low-flow fidelity (such
as trying to tune open loop at lower loads) then
before the cats will be a lot better. Though "for
tuning purposes" you might just swap in a pair
of hollow shells, and then you can use the rear
bungs. I got a separate bung welded onto my
I-pipe where it's accessible from the side, and
short enough for the cable to let me set the meter
on the passenger's seat.
goings-on, not much at WOT as airflow is large
but if you want reasonable low-flow fidelity (such
as trying to tune open loop at lower loads) then
before the cats will be a lot better. Though "for
tuning purposes" you might just swap in a pair
of hollow shells, and then you can use the rear
bungs. I got a separate bung welded onto my
I-pipe where it's accessible from the side, and
short enough for the cable to let me set the meter
on the passenger's seat.
