If boost pressure is significantly reduced due to a leak, the MAP reading will be

If boost pressure is significantly reduced due to a leak, the MAP reading will be

• A. Significantly higher than normal
• B. Roughly normal
• C. Significantly lower than normal
• D. Unpredictable

Answer: (C)

MAP measures the absolute pressure inside the intake manifold. In a turbocharged system, applying boost pushes this pressure higher than ambient. If there's a leak in the intake path, compressed air escapes before it reaches the cylinders, so the manifold can’t build up that extra pressure. The result is a manifold pressure that falls toward ambient, i.e., significantly lower than normal. That’s why a boost leak shows up as a low MAP reading rather than a high or unchanged one.

MAP measures the absolute pressure inside the intake manifold. In a turbocharged system, applying boost pushes this pressure higher than ambient. If there's a leak in the intake path, compressed air escapes before it reaches the cylinders, so the manifold can’t build up that extra pressure. The result is a manifold pressure that falls toward ambient, i.e., significantly lower than normal. That’s why a boost leak shows up as a low MAP reading rather than a high or unchanged one.