Aftermarket Catalytic Converters

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#21

10-24-2013, 08:36 AM

SteveM

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He mentioned playing with the upstream sensor by using bung extenders, which you don't want to do. The upstream sensor is before the cat and used to monitor air/fuel ratios and affects how the engine runs. The downstream sensor (after the cat) only tells if the cat is working.

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#22

10-25-2013, 09:24 AM

ross1

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Quote:

Originally Posted by SteveM

You don't mess with the upstream sensor at all, only the downstream if they need it.

Since aftermarket cats have less material to work with than oem, I would think you'd want to position the downstream sensor after the cat to get the most out of them.

Btw, on my 99 XJR the downstream sensor was positioned after the cat (oem). Looks like they changed it on the newer years.

THAT is the understatement of the century. I recently recycled some old cats laying around the garage. An OE BMW cat was $180 FOR SCRAP, an OE Buick cat was $120. The recycler says they pay $8 for aftermarket units.
That's all the testimony I need to know that aftermarket ones either won't do the job effectively or live long.
Caveat emptor.

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