Help with O2 sensor placement

[Joe98GT]

I had a BBK catted X-pipe installed and a few months after install the SES light came on and it was P0420 "Catalyst effeciency below threshold bank 1" so after doing some searching I just recently did the DIY Mil eliminator mod. Next day the light came back on. I have 2 questions:

1. it says that the placement of the o2 sensor is important. When I removed them the blue plug was on the driver side and purple plug on pass...can anyone verify that's the correct placement?

2. the DIY mod I followed had the resistor going on the gray wire and the capacitor jumping to the black...however another link (below) shows the resistor on the black wire. Can anyone confirm which is the right way?

$4.50 DIY O2 Sensor MIL Eliminators

Or a tuner in CT that could turn the rears off?

Thanks guys!

 

[trinity_gt]

I had a BBK catted X-pipe installed and a few months after install the SES light came on and it was P0420 "Catalyst effeciency below threshold bank 1" so after doing some searching I just recently did the DIY Mil eliminator mod. Next day the light came back on. I have 2 questions:

1. it says that the placement of the o2 sensor is important. When I removed them the blue plug was on the driver side and purple plug on pass...can anyone verify that's the correct placement?

2. the DIY mod I followed had the resistor going on the gray wire and the capacitor jumping to the black...however another link (below) shows the resistor on the black wire. Can anyone confirm which is the right way?

$4.50 DIY O2 Sensor MIL Eliminators

Or a tuner in CT that could turn the rears off?

Thanks guys!

Sorry, I can't comment on the connector colours (been far too long since I was under my car) but as for the MIL circuit, the schematic shown on the link you provided is what you want: a 1 megohm resistor in series on the signal wire with a 1uF capacitor on the PCM-side of the resistor to the signal ground wire. This is a simple single-pole filter:

I couldn't find a DIY you referenced saying to use another connection but the Paladin Micro one (above) is electrically correct. You should verify the wire colours used in the Mustang to ensure the signal and signal ground wires are properly selected.

 

[Joe98GT]

Thanks for the reply! Well I guess I have to take it apart and rewire it. I hope it didn't ruin them The link below is what I used...and it shows the resistor on the gray wire...last page on the same thread though I just noticed is the other one.

The home-made MIL's work! *pics* - MustangForums.com

 

[Joe98GT]

I have them off again and will rewire them tomorrow.

Nobody knows which side is which?

 

[cliffyk]

I have them off again and will rewire them tomorrow.

Nobody knows which side is which?

It doesn't matter. The sensors are identical as are the connectors with the exception of a keying tab that has to be cut off to make then fit on either side.

If you have two white wires, one black and one gray, then the sensors are after market replacements. The OEM sensors have multi-color wires as shown in this diagram:

 

[Joe98GT]

Is that the rear 02's or fronts? If that's the rears then I'm totally confused as the other instructions had the same color wires mine has.

 

[cliffyk]

Is that the rear 02's or fronts? If that's the rears then I'm totally confused as the other instructions had the same color wires mine has.

Those are the rear sensor's, the wire colours are for the stock sensors or Motorcraft OEM replacements.

If you have after market sensors the colours are typically as shown below: