Air Fuel mixture - Toyota Nation Forum : Toyota Car and Truck Forums

todd0305 · 01-01-2005, 04:10 PM

I want to install an air fuel gauge that my friend gave me but i don't have the instructions. I know the three wire are ground, power, and the last one goes to the O2 sensor but i'm not sure of which wire on the sensor to hook to.

automatic · 01-01-2005, 05:07 PM

Of the two wires on the O2 sensor, one is a ground; the other one is the one you want to hook up to your guage.
You should see some voltage from the wire you want to use, so testing by trying each wire to the o2 sensor while unplugged and running won't harm anything, just don't mess with the wires going back to the ecu.

JekylandHyde · 01-02-2005, 06:05 AM

He did not state what car he has ... if he has a turbo MR2, there are 4 wires on the O2 sensor. You want to tap into the BLUE wire.

Also, you need to solder the connection to get a good read on your A/F Gauge.

todd0305 · 01-06-2005, 03:29 PM

I did tapped it to the blue wire but the reading keep jumping back and forth on idling and also when normal driving. I reads rich when i slam on the gas and lean when i let go, then it would jump back and forth again. Is this suppose to happen?

What would normal readings be?

JekylandHyde · 01-06-2005, 06:37 PM

That is 100% normal.
At idle and during "cruise" the ECU adds fuel and takes it out for better fuel economy.
The gauge osciallating up and down is completely normal.

todd0305 · 01-06-2005, 07:10 PM

Just making sure. Thanks.