Checking Idle Air Control Valve
 

Hi again,
I'm pretty sure the IAC on mine needs cleaning out. It'd appear, since it sits on the underside of the Throttle Chamber, you have to remove the Throttle Chamber, so I've got gaskets (and some time) coming.

Once I get to it, is there any way to test it ? Maybe run a voltage to one of its wires (I'm guessing it just moves a 'valve' to open outside air into the plenum) ?

My car is a hard start when cold (no CE lights, no obvious vacuum leaks, and just did 02s). Once warm is no problem. Also, when cold the car shakes and RPM's drop - just like a carb'd car with no choke would do... I'm sure I need to get to it and attempt cleaning it out. I guess I just spray some Carb Cleaner in the main square hole on its top ? Maybe in a vacuum line ?
Didn't notice anyway to get to the actual valve by looking at the pic on subaruparts.com

Thanks for any advice on testing it !

Re: Checking Idle Air Control Valve
 

damn, i was just about to post asking if it can be removed without taking off the entire throttlebody!

i have the same symptoms - on freezing days when the car sits in the lot all day, it does what you said if i don't warm it up for a few minutes. i used to throw Cylinder#1 misfire codes if it was really cold out with no warm up. now i just make sure to warm it up before heading out, and its kind of a pain in the arse. i need to get it fixed real soon!

I cleaned mine out.
Yes, you have to remove the throttlebody from the intake manfold to clean it out.

:mad: i was hoping i didn't have to. oh well.

An exploded diagram and info from the FSB indicate that an "auxiliary air-control valve" assists in the control of bypass air when the motor is cold, as opposed to the "bypass air control solenoid valve" which controls bypass air after the motor reaches operating temp. It appears the aacv is attached via vacuum hoses to the throttle body on one side and the intake plenum box on the other. I'd be sure those hoses aren't hiding a leak, then assure that the aacv is operating correctly. It's referred to as a " bi-metal coil-heater and rotary valve" presumably switching off as engine heat/coolant reach optimum.
The bacsv appears to be on the underside of the throttle body and would probably require r&r of both to clean. A Trouble code 24 appears associated with the bacsv troubleshooting. Have you pulled any trouble codes?

Glenn

i assume the AAC valve is what i (and most other people/texts i've seen) refer to as the Idle Air control valve.

what, and where, is this "bypass air control solenoid valve"?

Quote:

Have you pulled any trouble codes?

just a "cylinder#1 misfire" code, when i didn't warm it up before starting out.

Alan, The bacsv is what I believe you're calling the iac, and is on the bottomside of the throttle body. It adjusts the idle in tandem with the aacv when cold and when warmed handles the chore alone. I can't tell you how much help it is to have the manuals.
I suppose, from what I've seen of the inside of the "collector" on my car, it could definitely do no harm to clean it up.

Glenn

OK, what's the FSB ? I assumed the valve on the bottom of the throttlebody controlled cold air on a cold engine. Perhaps the 'aacv' is the issue...if I can find it ?

Factory service manual or bulletin.

KuoH

Sorry Rob! That would be FSM(Factory Service Manual) as I got a bit carried away with the abbreviations. :o Looks like the aacv is under the collector to the driver's side of the car. You can see a hose coming off the TB running around the outside under the collector, and into the front of it with another coming off the rear of it and into the air plenum. There's a power lead on the front as well. Actually looks like the bacsv would be easier to access, and none of the troubleshooting steps take the aacv into consideration. Trouble code 24 has the tech testing(ignition ON) battery to the ECU(pin 14 conn B62 to body 10V ,min) harness connection between the ECU and main relay(resistance;pin 14 conn B62 to pin 4 conn B52; 0 ohms), power to main relay(pins 1&2 conn B52 to body 10V, min), input signal from bacsv to ECU(pins 1&2 conn B62 to body, 2=7V; 1=6V, min) and finally harness connector to the bacsv(resistance, pins 1&2 conn B62 to pins 1&3 conn E15 of 0 ohms) Am I just confusing the issue?

Glenn

Hey RojoRocket,

Thanks for the tips. A little confusing, but I'll figure it out this weekend. I'd rather have more, than less information !

Is the Collector the plastic Air Intake hose on the passenger side?

Thanks again !!!

Sorry for the delay Rob. I'm out of town. The "collector" is the large aluminium piece that attaches to the intake manifolds on either side of the motor. I would have referred to it as the intake manifold until seeing the breakdown in the manual. Best of luck with your project. Hope you get the idle back to a "purr".

Glenn

Testing the auxiliary air valve.
 

Glenn is on the ball, this rotary valve is closed by a bi-metal spring, that can get gummed up. When it is cold the spring opens the rotary valve, to allow extra air for a faster idle speed,when the ignition is turned on, the electric heating windings heat the spring to close the valve.

An easy way to test, is to pull the AACV hose that runs from the left hand side of the black box on the throttle bodies. When the engine is cold, you should be able to blow through the valve. Then turn on the ignition, don't start the engine, after a few minuits the valve should heat up, to close the valve, and you should not be able to blow through it.

Harvey.;)