FI harness question

[mhuppert4]

Hi All, I'm getting down to my last connections in my Carb to FI conversion and have a question regarding the FI harness. There's one wire inside the engine bay with a female spade connector on it. It goes to pin 22 on the ECU, but all the schematics I have found don't show any kind of connection to that pin. Pins 23/24 are for the exhaust manifold lambda, is pin 22 for the lambda just before the cat? Thanks for any light you all can shed on this.

thanks,
Mike

[htchevyii]

I know that an extra unused plug under the hood has come up before. Mine has it, on the pass side shock tower. I do not know where is goes, though.

[124JOE]

IDK but it sounds like an extra o2 sencer.if i ran FI in mine i might use that one as i have a headder without a plug hole

[spider2081]

I have a single female spade connector on the passenger side of my 81 that is not connected to anything. There is a white wire in it. I checked two FI wire diagrams and neither shows pin 22 of ECU used. So I think if you have traced this wire to pin 22 of ECU you are safe leaving it disconnected. I remember reading somewhere that early oxygen sensors had a ground spade connection on them. Both the sensors signal and ground were connected to the ECU. Now the engine is considered a good enough ground to complete the circuit.

[mhuppert4]

So here's the next question, does anyone with a FI car have a Connected O2 sensor in their downpipe right before the Cat Converter?