A/F Gauge Signal Wire on KA - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ChillyWilly3 · 03-30-2003, 11:33 AM

According to the 96 240SX wiring diagram, the 3-wire front heated O2 sensor has (1) blue, (1) brown and (1) white wire. The blue and the white wire connect back to the ECM. I assumed the signal wire is the blue wire and that the brown and white wires are the heater wires because the rear O2 sensor also has the brown and white wire, but has a black instead of blue for the third wire.

Anyway, after attaching it and running the car for about 4-5 minutes to get the O2 sensor heated up, I noticed the following: starts showing rich (~.95V) then gradually settles around stoich near the lean side (~0.55V) then stays there regardless if I'm at WOT or cruising. Also, when I turn on the accessories such as the wiper, headlights, etc., I see the readings affected (it's showing a drop in voltage).

I thought undet WOT (heavy load) I should see the A/F go rich then settle back to some stoich reading. Also, I thought at cruising speed, I should see the A/F gauge bounce back and forth because the ECM is constanly adjusting. Did I hook the gauge to the wrong wire? do I have a bad ground? do I have a bad O2 sensor (it's relatively new)?

Also, I have a turbo installed on the KA, so I should be shooting for 13.2:1 ratio (~.9V), correct? I heard 12.0:1 ratio from other threads. Hmmm...

Thanks...

03-30-2003, 11:33 AM	#1
ChillyWilly3 Join Date: Jan 2003 Location: Maryland, USA Posts: 9 Trader Rating: (0) Feedback Score: 0 reviews	A/F Gauge Signal Wire on KA According to the 96 240SX wiring diagram, the 3-wire front heated O2 sensor has (1) blue, (1) brown and (1) white wire. The blue and the white wire connect back to the ECM. I assumed the signal wire is the blue wire and that the brown and white wires are the heater wires because the rear O2 sensor also has the brown and white wire, but has a black instead of blue for the third wire. Anyway, after attaching it and running the car for about 4-5 minutes to get the O2 sensor heated up, I noticed the following: starts showing rich (~.95V) then gradually settles around stoich near the lean side (~0.55V) then stays there regardless if I'm at WOT or cruising. Also, when I turn on the accessories such as the wiper, headlights, etc., I see the readings affected (it's showing a drop in voltage). I thought undet WOT (heavy load) I should see the A/F go rich then settle back to some stoich reading. Also, I thought at cruising speed, I should see the A/F gauge bounce back and forth because the ECM is constanly adjusting. Did I hook the gauge to the wrong wire? do I have a bad ground? do I have a bad O2 sensor (it's relatively new)? Also, I have a turbo installed on the KA, so I should be shooting for 13.2:1 ratio (~.9V), correct? I heard 12.0:1 ratio from other threads. Hmmm... Thanks... Last edited by ChillyWilly3; 03-30-2003 at 11:38 AM..