SOURCE: HAVE A TROUBLESHOOTING MESSAGE PO446
DTC P0446 Evaporative Emission (EVAP) Vent System Performance
The vehicle control module (VCM) monitors the performance of the evaporative
emission (EVAP) system by applying a predetermined level of vacuum to the
EVAP system and monitors the vacuum decay rate. The VCM sets this diagnostic
trouble code (DTC) if the vacuum decay rate is more than a predetermined
value. The VCM monitors the amount of vacuum and the amount of pressure
in the EVAP system by monitoring the fuel tank pressure sensor. For
this DTC, the VCM turns ON both the EVAP purge valve and the EVAP vent
valve when the Conditions for Running the DTC are met. This applies
an engine vacuum to a closed EVAP system. The VCM turns OFF both the
EVAP purge valve and the EVAP vent valve when the system reaches a correct
amount of vacuum. The EVAP system should quickly RELEASE the vacuum
in the EVAP system with the EVAP purge valve OFF and the EVAP vent valve
OFF (open). This test indicates a blocked or restricted EVAP vent path
if the EVAP system fails to release the vacuum quickly enough.
SOURCE: purge solenoid location
which vehicle are you actually looking for the purge solenoid on? you have 2 vehicles listed in your question. i'll answer both, lol
the locations are described as if you are looking at the engine from the front of the car with hood open.
on the blazer:
it is located on the left side of the intake manifold just under and behind the throttlebody. it is a canister looking device.
on the silverado:
it is located on the intake manifold on the left side in about the same spot as the blazer. providing the silverado has the 5.3 or 5.7 liter engine. if it also has the 4.3 then obviously it will be the same.
hope this helps!
SOURCE: expansion valve location on 1998 chevy cavalier
It does not have an expansion valve. It has an orifice tube.
SOURCE: 2004 Chevy Cavalier 2.2 eco Automatic 94,000 miles
in my experience the usual culprit is the evap cannister. the problem is it gets moisture in it and freezes during winter thus cracking the plastic. if you lay under the car and look at the evap box it black plastic and if you see a loose or cracked hose or the box itself is cracked that is most likely it. as a side note you can check the gas cap and buy a new one to see if that rectifies the situation. lastly i don't think the gas tank should be suspect as you would probably notice if gas was leaking out of the tank. if you take the car to a dealer or shop they can do a smoke test and determine where the leak is.
SOURCE: where is the purge solenoid
Hope this helps, it it does please leave feedback and vote Thank You and Good Luck
Canister Purge Solenoid
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