🔍 Key Concepts

• Exhaust flow path from the cylinder to the atmosphere • Difference between intake restriction and exhaust restriction • How back pressure develops in a flowing system

💭 Think About

• Trace the path the exhaust gases take leaving the cylinder. Which component, if restricted, would most directly resist that flow and build pressure? • Which options mainly affect how much fuel goes in or when it goes in, versus which affect how easily gases can get out? • Think about what the term back pressure literally means: pressure pushing back against the flow. What would physically cause that?

✅ Before You Answer

• Identify which choice describes a restriction in the exhaust side, not the intake side or fuel system. • Separate causes that change combustion quality from those that change gas flow resistance. • Verify which component, if plugged or obstructed, would create a pressure buildup after the engine but before the outlet to atmosphere.