> Common causes of feedback carb vehicles not going into closed loop: >
> Engine Coolant Temperature reading fault - the PCM thinks the engine is
> still too cold.
I finally found the Coolant Temerature sensor. It was located below the carb on the intake manifold. There is a separate sensor for the temp gauge on the front of the engine. Disconnecting the connector the sensor reads 315 ohms when the engine is hot. Anyone have any idea what it should read?
> O2 sensor reading fault - the PCM does not see the voltage on the O2
> sensor as high or varying and doesn't think it is warmed up enough to
> provide accurate feedback.
>
The O2 sensor is new but I have yet to trace the wiring back to the computer to measure the voltage there. The O2 sensor is on the exhaust manifold on the left side of the engine. The wire runs around the back side of the engine to somewhere under the carb to a connector. The replacement sensor had a splicing lug and said to cut the old wire off the old sensor and splice there. That wire is black but I have already found out that wires change colors when they go through connectors on this vehicle.
Wide open throttle indication seen by PCM - this would be remote and
> would more than likely throw a trouble code.
>
If this carb has a throttle position sensor I can't find it. There is a micro-switch that is called and idle switch on a picture in a Motor's manual. The two wires (a green/orange and a solid green) do go back to the computer. I don't know if this system even has codes. I have not seen anything about them. There is no check engine light. It only has a EGR light that comes on every 60,000 miles. The owner's manual says this indicates that maintenance is required for oxygen sensor, E.G.R. control valve, P.C.V. valve, hoses and tubes and iginition timeing in the emission control system. There is a wire under the dash that you move to a different connector to turn the light out for another 60,000 miles.
Van