Twin O2 sensor question

[Chris Wilson]

Hello EFI,

I am about to remove the 2 cats from my Supra twin turbo (1994) to
alleviate any restriction, but I have a question. Currently, there is
an O2 sender just after the 2 turbos join at a common outlet point,
then a pre cat, then a bit of plain pipe, with what *appears* to be a
second 02 sender, and about 2 feet further back, a second, main cat.

Out of curiosity I removed the second 02 sensor, and it appears to be
a simple straight stick, about 3 sixteenths inch diameter, where it
enters the exhaust stream. Is it an 02 sensor, or some sort of
temperature probe? The car is a Jap import, hence Japanese spec,
slightly different to US and Europe spec Supras, in that the turbos
are smaller, have ceramic turbine wheels, and the air flow is measured
by a vane type AFM, but uses a MAP sensor.

If I remove both cats, and make up a plain pipe section to replace
them, and re fit both (what I assume to be...) 02 sensors, how will
the ECU react??? I assume it will be happy, as it seem,s a common
enough mod. But why 2 02 sensors in the first place?

Thanks, I'd better ask before cutting .... :-)

-- 

Best Regards,
 Chris                          

mailto:chris at formula3.demon.co.uk

http://www.formula3.demon.co.uk

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