>  No exhaust leaks
> either. Sorry, but I had a van come in for this procedure and he had a
> major leak at the two into one collector.  As a result the O2 input was
> usless.

Someone explain this to a dense guy.  Wouldn't the exhaust leak
OUT, rather than air leaking IN to confuse the O2 sensor?
Or does the "pulsing" of the exhaust gas cause it to switch
back and forth?  I don't understand....

Thanks,
                        Richard A Jones
                        Boulder, Colorado