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Old 06-24-2009, 10:12 AM   #261
Scooby Specialist
Member#: 133012
Join Date: Nov 2006
Chapter/Region: MWSOC
Location: Kansas City
2015 STi
Lightning Red


I just wanted to bump this, SOA has no specs to clean this (they just replace it) but cleaning it CAN help in most cases.

Soaking in gasoline seemed to be the best method for me (I tried alcohol first). Also, you cant really clean the valve that well without first removing the plastic-bodied stepper motor. There is a rubber o-ring between the valve body and the motor, remove that. You will see the end of the drive for the valve (its magnetic). Take note of the metal tab thats on the magnet, as it will help with reassembly. This piece should turn freely (spin very easily) if not, chances are its gunked up. There is also an NSK bearing that the shaft passes through. This bearing is NOT sealed (i.e. its exposed to the same gunk and blow by), and it seems like that it tends to gunk up over time. However, with the way that it is pressed into the valve body, it cannot be (easily) replaced. Instead, soak the whole valve body in gasoline, and spin the shaft by the magnetic end to work gasoline into the bearing.
Clean with swabs as you normally would, focusing on the top of the blade and the two shaft ends. You will want to flush the body a few times with clean gasoline. I also filled the body with gas and allowed it to flow out through the bearing while spinning it.
Eventually, the shaft will begin to spin freely. You may notice a few spots of light interference, from what I can tell, this is where the actual valve blade sometimes nicks the edges of the valve body when spinning, but it provides no real resistance. This is from either loose tolerances on the valve body, or the bearing wearing and allowing for some transverse play in the shaft.

I also wanted to note, my car was suddenly showing a high idle, anywhere between 1100-2000 rpm, sometimes idle hunting between 1200-1700 rpm, and causing a major hesitation between 1800-2000 rpm when transitioning between an idle throttle position and throttle tip-in. The car then threw a P0519, and after cleaning just the valve body with alcohol the problem remained, and then threw the P0519 and P0507. Idle conditions also varied greatly depending on ambient and engine temperatures.

As far as hardware replacement goes, replacing the soft OEM screws with a M5 X .8 20mm SHCS (Socket Head Cap Screw) is a good idea, but make sure you pick up some new flat washers and spring washers as well. Also, be careful as to NOT over tighten the cap screws when replacing the IACV, as the threads in the throttle body are extremely soft and strip out easily. This becomes even more apparent when you replace the hardware with something harder than stock (like most SHCS are).
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