Practice Test Geeks(CPT) Certified Process Technician Practice Test
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Engine Performance & Tuning Flashcards

7 cards from real CPT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Engine Performance & Tuning flashcards as text

  1. What does a manifold absolute pressure (MAP) sensor measure?

    Answer: Absolute pressure inside the intake manifold

    The MAP sensor measures the absolute pressure in the intake manifold, which the ECU uses to calculate engine load for fuel and timing control.

  2. A technician notices that idle quality improves when a specific injector is unplugged. This finding most likely indicates:

    Answer: That injector is leaking or flowing too much fuel

    Removing a leaking or over-fueling injector from the circuit reduces the rich condition it was creating, thereby improving idle quality.

  3. Which condition would cause a scan tool to display a negative short-term fuel trim (STFT) value?

    Answer: Rich condition detected by the O2 sensor

    The ECU pulls fuel trim negative (reduces fuel delivery) when the O2 sensor indicates a rich exhaust mixture.

  4. A restricted fuel injector will most noticeably degrade performance under which condition?

    Answer: Wide-open throttle (WOT) at high RPM

    At WOT and high RPM, maximum fuel delivery is demanded; a restricted injector cannot supply adequate flow, causing lean misfire and power loss.

  5. What is volumetric efficiency (VE) a measure of in an internal combustion engine?

    Answer: How effectively the engine fills the cylinder with fresh charge compared to theoretical maximum

    VE compares actual air mass ingested per cycle to the theoretical maximum based on displacement, reflecting how well the engine breathes.

  6. Which component in an ignition system is responsible for amplifying primary voltage to the high voltage needed to fire the spark plug?

    Answer: Ignition coil

    The ignition coil is a transformer that steps up low primary voltage (12V) to the high secondary voltage (20,000–45,000V) needed to jump the spark plug gap.

  7. A technician performs a leak-down test and finds 40% leakage past the intake valve. What symptom would this most likely cause?

    Answer: Low compression with hissing air audible at the throttle body

    Air escaping past a leaking intake valve during the compression stroke flows back through the intake port, producing audible hissing at the intake side.