Hi all, I think that system uses the Lambda sensor signal as the feedback sensor for that circuit.

When the system is in closed loop and the valve is opened the mixture will go high if the canister has fuel in it, and conversely when the canister is empty the signal will go lean.

Once the valve is open the ECU just modulates the injection time to bring the system back into the neccessary switching pattern for the Cat to work whilst the EVAP is open.

Regards mark