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Adjusting Throttle Blade Screws

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5:15 p.m.: Before you try to start the engine, you will need to adjust the two throttle blade adjustment screws on the throttle body. One is for the front throttle blades and the other is for the rear. The system will automatically adjust the idle using the idle air control (IAC) motor, but these adjustments allow you to get the throttle blades in a useable range, and lets the system compensate for a wide variety of engine displacements and camshaft profiles. For most engines, you’ll turn both screws one turn past when the throttle starts to move. Once the engine is running, you use the handheld controller to check that the IAC count is between 10-20 with a manual transmission or 5-15 in gear with an automatic.