S300/P72 Wideband Analog Input Proper Wiring

[TB123]

I want to make sure that I have my wideband setup for the most accurate readings possible by the ECU. I have a really high voltage offset (0.6 VDC) that is concerning, so I have a few questions that I was hoping someone could help answer.

• Does it matter which ECU input I use for the wideband (e.g., D10 ELD vs. D12 EGRL)? Is one circuit more stable or accurate than the other? If they are the same, I suppose D12 would be easier so that I don't need to remove the R136 and R138 inside the ECU. Does using the ELD input disable ELD in the vehicle, or only the ELD voltage measurement by the ECU (that is used for the CEL during a fault)?

• From the S300 User Guide: "The wideband should always be grounded to the same point as the ECU (the thermostat housing)."
  Does this suggest that the wideband ground wire should physically be run through the firewall into the engine bay and grounded at the screw on the thermostat housing, or is it better to splice into a ground wire on the ECU, close to the ECU connector (I believe this is either D21 or D22, brown wire)?

• I'm using an old PLX M-300 wideband (circa 2005). I found an old PLX manual stating that a 0.1 nF (25 VDC rated) is included with the wideband meter and is to be installed if using the analog output to an ECU. I don't believe that I ever had this capacitor and I have been running it for years without it, but if this can help give me a more accurate or stable measurement, I want to add it. Does anyone have any examples of how this capacitor should be wired? I have also found many posts on this forum stating that the capacitor is not needed, but didn't PLX recommended it for a reason?

• From the closed loop section of the S300 User Guide: "Disable the o2 heater if the stock oxygen sensor is physically present." I don't understand this. When using the stock NB sensor for closed loop corrections, why should the heater be disabled in closed loop operation? I also read an older post stating that if you disable the heater, you should add a resistor to the heater circuit. Why is the resistor necessary if it's disabled?

[Spunkster]

Either of those should work as long as they have the proper components for them. ELD must be disabled if that input is used.

Either at the thermostat housing or at the ECU will work.

It is not needed.

Are you running closed loop from the wideband sensor?

[TB123]

Thanks for the reply

Either of those should work as long as they have the proper components for them. ELD must be disabled if that input is used.

Is one considered a "better" (more accurate) input? Is ELD actually disabled in the vehicle, or is it just not monitored by the ECU? With ELD disabled, does the alternator continuously supply maximum charge to the battery? Are there any downsides to this like excessive alternator load (decreased alternator life) or overcharging the battery?

It is not needed.

Would it be beneficial to use a capacitor (for signal integrity/accuracy)? I'm assume that PLX published that for a reason. I'm happy to add one, but I just can't figure out the proper way to physically wire that tiny capacitor into the circuit. If anyone could show an example, it would be greatly appreciated.

Are you running closed loop from the wideband sensor?

I've attempted this without success. I want to use the stock NB sensor (in addition to the WB) for closed loop operation.