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does the valve open and close?
Posted by Ken Fisher (more from Ken Fisher) on Sun, 1 Apr 2012 15:42:34
In Reply to: Got a better look at C Canister and Purge valve...., AndyRobertson, Sun, 1 Apr 2012 13:53:15
The voltage being present at all times is a clue that the wiring is intact from the Main Relay to the valve. At start up, that valve should be closed until the engine reaches more than 150-160 deg F(i.e. when the fuel injection migrates away from coldstart mixture). The O2 sensor readings are ignored until out of coldstart. The ECU is going to toggle the purge valve to learn its state.

The O2 sensor monitors run when this valve is closed. When the valve opens, additional oxygen flows into the intake, and the ECU is looking for that change at the front (upstream) O2 sensor. This is how the ECU knows the state of the purge valve.

I would remove the valve and try to toggle it open and closed with a 12 volt source independently. Looking at a wiring diagram, the grey-white wire is a homerun to the Main Relay, that is the 12 volt source that is hot in RUN. The other side of the purge valve coil is tied to ECU pin 27 on a yellow-red wire. The ECU is going to sink 12 volts (logical ground) on this pin to actuate the valve, or turn the pin open-collector(High impedance) which would deenergize the valve coil.

So you've measured that the valve coil is intact, but not whether the valve can change state. If you remove the valve, attach a short length of vacuum hose and try to blow through the port. You'll know if the valve is open or closed.

posted by 98.248.173...
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