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PPG Auto Refinish
12-Apr-07 Relocating the Idle Air Controller Part 3

Adding a block-off plate

ImageSome aluminum fittings were ordered from Pure Choice Motorsports to mount the Idle Air Control (IAC) .This consists of a male pipe to AN fitting and an AN bulkhead fitting. There are also two large washers (not pictured) that will rest on each side of the opening in the injector hat.
ImageI made a blocking plate out of 1/8-inch aluminum the same size as the factory plate on the other side and cut and folded back an area for the IAC to mount.
ImageThe intent behind relocating the IAC is to clean up the area behind the blower and to eliminate the long distance that the air needs to travel to get into the injector hat. I've been told that you can have the IAC up to 20-inches away and it will still work but I can help but think that it could cause two adverse effects. First, as the IAC moves to allow more or less air into the injector hat, there could be a delay that could cause it to over compensate in either direction. Secondly, the longer a tube is, the more it restricts airflow.
ImageBy cutting a slot and bending a tab to mount the IAC, I was able to easily find the best mounting angle. The IAC must be easy to slide in and install from the open butterfly.
ImageAn angled cover was also formed from the aluminum that will be welded in place around the opening, making it air tight. This is how it will look inside when finished. The air at idle will have a very short distance to travel and deposit the air at nearly the center of the plenum. The duct tape is temporary :)
ImageThe hat was disassembled and taken to the welding shop. I labeled the butterflies because they fit best a certain way. Although the butterflies appear to close air tight, there are always slight gaps if you hold it up to the light. By eliminating one of the butterflies, there will be about half the air leakage at idle.