Sensor documentation.

[colchiro]

I found a nice collection of documentation on Toyota sensors, their location and troubleshooting and theory. I thought I'd share. http://www.autoshop101.com/autoshop15.html
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Rick

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[colchiro]

Forgot to include the description and testing of the Toyota air/fuel sensor.

If you're planning any kind of mod that uses or modifies the o2 sensor output, you should read this first. Unless it's designed to work with an air/fuel (not a conventional narrow-band or wide-band) sensor, it's probably not going to work.

[update 7/5/2008]
If you want to dig deeper, SAE #930233: A Study of a Wide Range Air-Fuel Ratio Sensor for Exhaust Emission Reduction
and SAE #930232: Air Fuel Ratio Sensor and Its Signal Processing Module

[10/13/2008]
More info on the Toyota air-fuel sensor: http://artofhacking.com/IET/PHACTS/live/aoh_afr.htm
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Rick

[colchiro]

Here's Toyota Trouble codes OBD1 and OBD2: http://www.troublecodes.net/Toyota/
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Rick

[colchiro]

Here's a way to lean out your air-fuel mix by tweaking the MAF sensor:



See the upper left portion of this image. (The right side is plans for dual controls, like city, highway.)

Parts needed, small project box, 50k linear 1W potentiometer, 33k 1/4 resistor, small knob, SPDT switch and wire. Parts should be available at your friendly neighborhood Radio Shack store.

Cut your MAF sensor wire (by the sensor under the hood, or by the ECU in your vehicle). Usually this sensor is between the air cleaner and the engine.

Take a 50k pot and connect one end of the pot to the output of your MAF sensor (green wire in diagram), center terminal of the switch goes to the ECU side of that cut wire (black wire in diagram) and the other end of the pot to ground via a 33k.
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Rick

[colchiro]

Nice source of info on o2 sensors and trim:

http://www.4x4wire.com/toyota/4Runner/tech/OBDII_ECU/

Good info on oxygen sensors: Oxygen Sensors: How to Diagnose and Replace
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Rick