seen this below from youtube comment but no idea whats involved in doing this if any youtube video has below procedure >> prius knocks on cold mornings just pull up the airbox and wipe the underside of the butterfly valve out with a paper towel there is usually oil and water puddles sitting at the bottom the intake under the valve. Its a defect of the third gen.
Not a defect it’s just what the atkisson cycle engine does. It will always have a pool of oil in the bottom of the intake. Don’t use paper towels in there they can disintegrate and pieces of towel get in there. I always use a ripped up t shirt in strips I soak them in carb cleaner and gently hold the butterfly open and stuff a strip in there and rub away. then remove it and use another strip. But this will not fix a knock in the morning. That may be oil related but I assume you have completely cleaned the EGR system at a minimum.
