To busybenz and Dennis and jr811: Just a note to ensure understanding of a basic principle...the aux air valve is supposed to raise the idle speed when the engine is cold and as the engine warms, it gradually closes off the aux air passage and lowers the idle speed down to the normal setting. There is a piston inside the housing that slides up and down to open and close an air passage. It is fitted with a thermostatic pellet that is immersed in the coolant. It operates just like the other thermostat in the engine. In fact, one repair that is sometimes made is to replace the pellet with a fresh one removed from a standard thermostat.

If your cold idle is way high, above 1500 rpm, then someone may have tinkered with the idle air screw, the large adjusting screw nearby the aux air valve. A mechanic may have tried to make an adjustment when the aux valve was sticking, a common event. Usually the screw gets turned down to drop the warm idle speed because the aux air valve has stuck part open and won't close the air passage. If you are getting a higher cold idle and a low, or normal warm idle, then it sounds like your aux air valve is fine and does not need attention.

Again, check the warm idle speed, it should be 700-800RPM. If it is too high, adjust the idle air screw at the front of the engine to get the right speed. Then when the engine is cold, see what the tachometer registers, it should be around 1300-1500, more or less.

Bear in mind that these older models usually will not operate as well as we have grown accustomed to with our modern EFI equiped cars. A lot has changed in 30 years and new cars today are really good on driveability whether hot or cold.

As to the way it was designed, it seems they were trying to mimic the operation of a carburetted engine. They have high idle speed when on the choke and as it opens up the idle speed drops. But our old FI engines do not have a choke. The electric cold start valve briefly dumps extra fuel to start the engine, then the higher speeds provided by the aux air valve help to prevent stalling while the engine is warming up to normal temperature. This is why cold operation driveability complaints were fairly common, or so I am told by others who know a whole lot about these things...

Just some additional food for thought, for what it's worth.

230/8