Checking idle control valve (ICV)
 

Good morning - hope everyone had a good weekend.

I am trying to sort of an idle issue with my '74 with a 3.2 and I just pulled the ICV. I cleaned it with carb cleaner and when i shake it I can hear the piston moving. I have 40 ohm resistance between the outer pins, and 20 between inner and outer.

That suggests that the ICV should be in working order, correct?

Thanks!

You can use a 9v battery and put power on the ISV; this will cycle the valve open and closed.

http://forums.pelicanparts.com/porsche-911-technical-forum/360766-bench-testing-carrera-idle-control-valve.html

When you put the ISV back on, you can reset your base idle by bypassing the ISV and adjusting the air bypass screw on the throttle body. This will give you a good baseline to start from.

Thanks Jon

When plugged back in, and with the key ON (eng off), you'll feel it vibrate and might hear the buzz. This tells you the DME is powering/ driving it.

Just check and the unit is vibrating. I think I have a microswitch issue.

Thanks!

My '87 started surging pretty badly. I removed the ICV, cleaned it, and verified it worked using a 9 volt battery. However, the engine still surged. I ultimately bought a used ICV and swapped it out. Haven't had a surging problem since.

Mine had the same problem. Found out someone installed the ICV backwards with the arrow pointing up.

It's a consumable, got one online problem solved for another 30 years....

OP, so what was the issue to suspect the ICV?