A/F ratio gauge

[malice10985]

Regarding a 99 L36 with a 4 wire o2 sensor, which wire sends a signal to the computer? I found 2 brown wires, 1 white and 1 purple wire. I bought a cheap sunpro A/F gauge, which is supposed to take its signal from th stock 02 sensor via piggyback wire clamp. I clamped the gauge to the purlple sensor wire, and it gives me crazy readings. Does anyone know which of the 4 wires is the correct one, or do I have to try all 4 and butcher the harness?

[Wicked 3800 V6]

Crazy readings maybe, but it will be crazy at idle, afaik. Reads only correct during throttle stuff -- accurate at WOT, roughly.
But maybe i'm wrong. But hey, you're on the right track. Hooray for gauges. [img]smile.gif[/img] (I've got a few)
-Rob

[malice10985]

The gauge varies wildly (Full rich to full lean) during all operations except WOT, where it reads slightly rich. If I do have the right wire, then I have a sloppy computer. I thought it would be more accurate.

[SilverTAWS6]

Nope, that's exactly what the gauge does.
Our cars (and most) have narrow band O2 sensors which don't read a/f ratio well. That's why when you get a dyno with wideband they hook up their own O2 sensor.

Basically the gauge is good for nothing more then a pretty light show. I know b/c I have one.

Chris