question about air aux valve

dan476 · 03-14-2007, 07:56 AM

I took the valve off and put it in warm environment - after a while it closed, Then i put it in the freezer overnight - when i took it out it was partly open (very little hole) - so question is - is it supposed to open fully when its cold?

SoCal Driver · SoCal Driver's Garage

Idle valve on early 944's is supposed to be open when cold. There is a heating element in the unit that causes the bi-metal spring to expand and close the gate. This would lower the idle rpm's. Many times the gate is clogged up with old oil and other crank case residue. Use carb/brake cleaner.

Later 944's use an active or servo valve to control the idle through the DME.

dan476 · 03-14-2007, 12:49 PM

used carb cleaner, had it sit in it for a bit, then moved the diaphragm open and close manually - no problems, but it doesn't do it on its own, just keeps it closed all the time with less than 1/4 of the hole opened.

SoCal Driver · SoCal Driver's Garage

Could be that 1/4 open is all it takes to raise the idle the necessary amount. I have not looked through an early idle valve so I can't tell you if 1/4 open is typical.

dan476 · 03-14-2007, 06:32 PM

Does anyone know if the valve is supposed to open fully when cold (after about 6hrs in the freezer)

Thanks

badjones · badjones's Garage

Hey there. Was there symptoms of low idle when cold? I'm no expert but I'm fairly certain that the valve does not open fully when cold, and that the specific shape of the opening that is exposed when cold is tuned to the airflow need of the motor to raise idle the correct amount. The only variation between the 944 part and the other many types of very similar valves in other vehicles that look identicle is the cutaway shape in the valve. The valve travel is adjustable and I have tuned them by applying power to the plug and waiting till the valve has stopped closing ( a minute or so ), and then setting the adjustment so that the valve is just closed fully. Works for me.

dan476 · 03-15-2007, 03:36 AM

how do you set the adjustment?

badjones · badjones's Garage

You will find it shouldn't need adjusting but if its not closing fully there is a 7mm nut on a stud on the main valve housing that can be loosened and moved. If you adjust that so the valve only just shuts fully after having 12volts applied for a minute or so then you know it is adjusted to open as far as possible when cold, giving the greatest airflow when cold. This assumes that the valve is not blocked up with crap.