Re: 96 Aerostar - Vacuum Purge Valve?
Having fought with my 96 Aerostar emissions and having the Purge Vlave and Sensor a large part of the struggle, I can tell you if this valve is stuck open or the vac lines connecting it are cracked you will get a very significant amount of raw/unmetered air into the intake. If the lines are cracked the circuit won't show pressure change and the sensor will not "sense" and the code will pop. If the valve is bad, then the same result will happen; system triggers valve, no valve action, no pressure change, no sensor trip, CODE pops. When it works properly with hoses intack, valve and sensor known good, the system triggers the valve, the valve opens letting engine vacuum draw the purge lines down, the sensor senses this and confirms to the computer that it is working.
The purge vac circuit is fed with a primary connection right into the throttle body behind the butterfly. The valve and sensor are not that expensive and fairly easy to change. The sensor might have to come from the dealer but mine was only about $15 and the valve was about $12 from the local parts man. You will have to pull the air cleaner box to get to the lines, but there is plenty of room down there to work. Just make sure you keep the connectors and stuff sorted when you disassemble. The little hoses are pre-bent for location/clearance.
Hope this helps...
Martin from PDX
No speed limit on the water folks!!