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Old 12-14-2018, 07:04 AM   #12
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Join Date: Sep 2009
Location: near baltimore

Originally Posted by vwblue1967 View Post
So to be sure should I be getting the .4-.9V from the black wire? and should it be plugged in or unplugged? after letting the car warm up I tried to test the voltage there and got a .93-.95. If I'm testing it correctly I believe that means its just running rich and I guess that's in line with eh 1-1-3 code.
Yes, you should see the voltage on the black wire kick back and forth between about 0.2 and about 0.8V, switching between lean and rich respectively. The wire needs to be connected. That's how the O2 sensor keeps the average mixture correct.

When it switches below about 0.5V, the ECU is programmed to push more fuel, by lengthening the time the injector valve is open until the O2 reports above about 0.5V, when it will cut back that injector's open time. Like the thermostat in your home. Feedback.

So, if it reports a constant rich signal, something else is not allowing the system to shut down the fuel. The fuel pressure regulator could be faulty, allowing fuel to bypass it through a leak in its diaphragm, or rarely, if it is stuck shut. The air mass meter could be falsely reporting more air than is actually flowing through it, or poor corroded connections might corrupt its message to the ECU. The coolant temperature sensor could be trying to tell the ECU it is minus 40 in the head, or its signal is not being faithfully delivered to the computer.

After some time the ECU has given up trying to get a reaction from the oxygen sensor, and has simply forced a rich mixture to protect the motor, and set the 113 code. Then you'll see it stuck at 0.9V or thereabouts.

Last edited by cleanflametrap; 12-14-2018 at 07:10 AM..
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