have a astra with a 1.6vvt z16xer engine and would like to understand how the vacuum controlled flaps within the sealed inlet manifold work, the flap. very much like a throttle flap I think? is operated via a vacuum solenoid electrically controlled from the ecu is it similar to twinport ?
As engine speed increases, the flaps are gradually opened until, at around 2,000 rpm, they are parallel to the airflow and present virtually no resistance. Their purpose is to ensure that the air entering the cylinder is sufficiently turbulent for good fuel-air mixing even at low engine speeds. This aids in reducing certain toxic emissions and may also improve low-end power and torque.