Practice question

What is an Exhaust Throttle Valve (Auspuffklappe / Motorbremse / Engine Brake) and how does it generate braking torque?

  1. It closes a butterfly flap in the exhaust manifold, creating high backpressure against the ascending engine pistons during the exhaust stroke to decelerate engine RPM and vehicle speed
  2. It closes the fresh-air intake completely so the engine cylinders operate without airflow
  3. It blocks the air intake filter completely
  4. It applies the wheel service brakes through the ABS modulator without using the engine

Answer: A — It closes a butterfly flap in the exhaust manifold, creating high backpressure against the ascending engine pistons during the exhaust stroke to decelerate engine RPM and vehicle speed

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