HELP! whistling noise from engine on acceleration
Champion
Joined: Jan 2013
Posts: 4,737
Likes: 374
From: Northwest Louisiana
1) Catalytic converters are very expensive because they use rare metals. To maximize the surface area of these rare metals, they are spayed on a grid system (like you saw above, except not broken) that the exhaust gasses must pass. This grid system gets heated to very high temps during use and the idea is that anything that is supertoxic will be burned up as it passes through it. (the catalyst - the rare metals- coverts the toxins in the exhaust.) The O2 Sensor checks to see how well that is happening and provides feedback to the engine.
The upstream O2s are used to feed back how well the engine is running, true. They work with, or without, a catalyst.
The DOWNSTREAM O2s mostly monitor that there's a change from the UPSTREAM O2s; but only the 1996 1st Gens have a downstream O2 sensor.
RwP
Administrator
Joined: Apr 2010
Posts: 87,267
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From: Clayton MI
Anything OBDII will monitor the cat(s).
Champion
Joined: Jan 2013
Posts: 4,737
Likes: 374
From: Northwest Louisiana
OTOH, the 1994 Thunderbird 4.6 used downstream O2s since it was basically OBDII (missed a couple of OBDII monitors, but can be read by most any OBDII scanner using the OBDII port on the ... passenger side of the dash.)
RwP