Turbocharger wastegate’s control the pressure produced by a turbocharger by acting as a bypass, allowing exhaust gases to flow past the turbine wheel. This robs the turbine wheel of necessary exhaust pressure. Without a wastegate, the turbocharger would produce maximum pressure at all times. This will cause engine damaging detonation.
The gate is controlled by a diaphragm that moves an adjustable rod. In most of today’s vehicles the wastegate is computer controlled. The computer senses signals from different sensors like the knock and oxygen sensor to make adjustments.
A sticking wastegate or faulty diaphragm can result in performance issues. A stuck open wastegate results in poor high end performance by allowing exhaust pressure to bypass the turbine wheel. A stuck closed wastegate results in damaging overboost by providing maximum pressure at all times.