I ve got 2 oxygen sensors and 4 holes for them in the exhaust system (2 before cats and 2 after cats). How can I find out where to put the sensors and how many of them does my ECU support? I ve heard that some ECU's support 2 lambds and some 4 of them and those which support 2 of them can be installed only after cats. RAVE doesn't tell much about it. Need your experience.
V8 4.0l Gems

 

'96 plus 4.0 uses 4 O2 sensors.