Pre Cats & O2 Sensors?
 

I just removed both exhaust manifolds and need some advice on whether I need to be replacing or checking anything while I have them off. Should I put new manifold gaskets on or use the old ones? I am also gutting the pre cats, so should I use new Mazda O2 sensors or universials? Correct me if I'm wrong, but I should only need the 2 upstream sensors, and need the part #'s! I odered a Dual O2 Simulator from Baker Electronics and 2 resistors to eliminate the 2 downstream O2 sensors. Does anybody have any experience and advice on doing this?

RE: Pre Cats & O2 Sensors?
 

Have never been a fan of aftermarket O2 sensors. Here are OE numbers. Left upstream is a
KJ01-18-861A-9U. Right upstream is KJ02-18-861C-9U. Would definitely replace the manifold gaskets as you would not want to go back in later for a leaky gasket and they are only $6.35 each from dealer. Part #KL68-13-460 both side gaskets are the same so just get 2. Have never installed a simulator but one of the other guys here has and said it was very easy to do. Direction included were very complete.

RE: Pre Cats & O2 Sensors?
 

Thanks for all your help! Here are some more part numbers for those Millenia owners who might need them! Down-pipe gaskets KL1940450, and the single pipe to converter gasket KL1440305! Also if anybody needs a newair box to throttle body gasket (air intake resonator grommet) its KJ0113245!

RE: Pre Cats & O2 Sensors?
 

Left bank downstream O2 sensor. (closest to the radiator ).

Green is the sensor signal wire to the PCM.
Black w/ Yellow stripe is sensor ground.
Red w/ Black stripe is 12 volts in for sensor heater from the main
relay.
Black w/ Blue stripe is sensor heater ground thru the PCM.

Right bank downstream O2 sensor.

White is the sensor signal wire to the PCM.
Black w/ Yellow stripe is sensor ground.
Red w/ Black stripe is 12 volts in for sensor heater from the main
relay.
Black w/ Red stripe is sensor heater ground thru the PCM.

RE: Pre Cats & O2 Sensors?
 

I got the car back together and it runs great! It feelslikea whole different car! I dont know how these cars even run with the precats being so restricted! I would guess it feels like 10 to 20 HP difference. I still got the TCS to figure out, but I will keep you all posted! Peace out my people!