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Message: <blockquote data-quote="UselessPickles" data-source="post: 536346" data-attributes="member: 3256">I still think this is unnecessary because the CO adjustment is used to balance the amount of fuel provided by the 4 injectors. The amount of fuel needs to match the amount of air. A throttle body synchronization balances the amount of air passing through the throttle bodies. The CO adjustments (fuel injector balance) were already performed at the factory based on balanced throttle bodies. Changing the airbox will throw the throttle bodies out of balance, but it doesn't affect the fuel injector balance. yes, at this point, the CO readings will be out of balance because there is an imbalance to the airflow. If you then balance the throttle bodies, you will return to balanced airflow matched up with balanced fuel flow. But if you instead balance the CO readings, then you'll end up with balance air/fuel ratios between the cylinders, but the absolute amounts of air and fuel will be out of balance. That would lead to an imbalance of power produced by each cylinder.It is worth mentioning that the adjustments made during the official throttle body synchronization is causing adjustments to a bypass airway (that bypasses the butterfly valve in the throttle body). These adjustments are most effective at idle, and become less significant as the throttle is opened. It is possible that the "unofficial" throttle body synchronization after an airbox mod may be helpful to bring the throttle bodies back into balance at wide open throttle.</blockquote>

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