yoda84

so now i come to believe that my air valve is not working i think its a auxilary air valve not sure book says air valve. truck is a 92 3.0 i did what the book says to turn idle screw in when cold & RPM should drop then when hot turn in & RPM should not drop so i do that and rpm still drops so what do. i called the parts store and they dont sell nothing like this.

abecedarian

Have to think about what the AAV does... it's open when the engine is cold and closed when the engine is warmed up. It allows air to bypass the throttle plate, thus acting like the fast idle cam in a carb'd vehicle. The ECU reads the coolant temp and determines how much fuel is required in order to perform the other part of the "choke" operation.
If the engine is warmed up and the AAV is closed, like it should be, idle speed is only determined by the idle-air bypass screw so turning the screw in (or out) will affect idle. When cold, the amount of air allowed by the screw is lower with respect to the air allowed by the AAV so the screw won't affect idle as much when cold. The engine is more sensitive to air/fuel mixture when warm when cold, if that makes sense.