This has to be my 20th time clearing the dreaded code, and I’m at a loss at what it could be. I have replaced just about every EVAP component, and it’s still not satisfied. I have replaced the following: Canister, solenoid, fuel cap, blew air through the lines to clear them, it has a strong vacuum. What else am I missing? Also, anybody know a solution for the 2 way elbow at the charcoal canister? Thank you! (1996 Dodge RAM 2500 5.9 V8 Magnum.)

 

The vehicle specific description for the code is "Insufficient or excessive vapor flow detected during evaporative emission system operation". The PCM uses a way wonky mechanism to determine flow as there is no direct way to measure it. It looks at changes in short term fuel trim and/or RPM when it purges the canister as that basically adds air/fuel.

First I'd check the solenoid. With the ignition on there should be power on the green/black wire. If you connect the pink wire to ground it should click. That way you can verify it properly opens and closes, disconnect the lines and use a short piece of hose to create your own vacuum.

If that checks out see if the PCM actually has control of the purge solenoid. There are a number of different conditions that have to be met to activate purge during normal operation but you could try to hold your finger onto the solenoid and feel if it starts clicking during warmup and idle. Kind of a crapshoot, the best way would be to use a bi-directional scan tool but you probably don't have that.