Idle Control Valve

russdeane · 01-26-2015, 07:54 PM

I have a 1977 Porsche 911-S Targa with about 40,000 miles. My Idle Control Valve is failing. Any ideas where I can find a new or rebuilt Idle Control Valve

Hil911 · Hil911's Garage

Hi

Does a 1977 911S with CIS HAVE an idle control valve? I would have expected a thumb screw like a 1976 system. There are a couple of other valves, like the auxiliary air regulator. Is that what you mean?

Check out Jim's basement 911 CIS primer.

T77911S · 09:26 AM

its an aux air regulator (AAR). people sometimes call them an ICV.

to me its not even an air regulator. it does not regulate anything. its more like a hi speed air valve.

you should try cleaning it. check the resistance of the heater. it should be around 33 ohms.
i am not really sure what you mean by "its failing". these things usually either work or they dont.
all they do is open up to let more air in to raise the idle when the engine is cold, then they close to drop the idle and do nothing more after about 5 minutes.

meant to say cold.

cmonref · 01-28-2015, 06:26 AM

Quote:

all they do is open up to let more air in to raise the idle when the engine is closed, then they close to drop the idle and do nothing more after about 5 minutes.

It opens, letting in more air, when the engine is COLD (not closed), then closes which decreases the idle as it warms up.

russdeane · 01-28-2015, 09:21 AM

I may have misspoken about the Idle Control Valve. Once the car is warm, it will not idle. The engine will increase a few hundred RPM and then correct by dropping to a level where it barely stays running. Then it will rev up and drop and shut off. That seemed to be idle control. Is there another fix

T77911S · 01-28-2015, 09:35 AM

thats not the AAV (ICV) causing it to cut off. in fact it sounds like it is working properly.

first thing you need to do is make sure the ignition is good working order.
plugs, cap, rotor, wires.
then check for air leaks
then check control pressures. (and system pressure)

if the idle surges (goes up and down) when warm that usually means its too rich. that can be caused by low control pressure or bad warm up regulator (WUR), or no power to the WUR.

you should also have a therm time valve (TTV) located on the left side of intake on one of the runners. there is a vacuum line from the WUR to the TTV then the throttle body. you can bypass the the TTV and see if that fixes your problem.