CPT Data Analysis & Interpretation Flashcards
6 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 6 CPT Data Analysis & Interpretation flashcards as text
When analyzing a dyno chart, a flat torque curve across a wide RPM range typically indicates what about the engine's tuning?
Answer: Optimal volumetric efficiency across the RPM band
A flat torque curve indicates the engine is producing consistent power output across RPM ranges, reflecting good volumetric efficiency and tuning.
On a wideband oxygen sensor data log, an AFR reading consistently above 15.0:1 at wide open throttle (WOT) indicates which condition?
Answer: Lean mixture
An AFR above 15.0:1 at WOT is lean, meaning insufficient fuel relative to air, which risks detonation and engine damage.
What does a sudden spike in short-term fuel trim (STFT) values to +25% indicate in a performance diagnostic?
Answer: The ECU is adding fuel to compensate for a lean condition
A high positive STFT means the ECU is commanding extra fuel because the oxygen sensor detects a lean exhaust condition.
Which data parameter is MOST useful for identifying knock (detonation) events during performance testing?
Answer: Knock sensor retard counts or ignition timing pull
Knock sensor retard data directly shows how much timing the ECU is pulling to protect against detonation events.
A technician reviews data logs and sees that volumetric efficiency (VE) drops sharply above 5,500 RPM. What is the most likely cause?
Answer: Cam phaser malfunction limiting intake duration at high RPM
A VE drop at high RPM often points to cam timing issues, restrictive intake, or cam phaser failure limiting airflow.
When interpreting an oscilloscope waveform of an injector signal, what does a longer pulse width (ms) indicate?
Answer: Greater fuel delivery to the cylinder
Injector pulse width is directly proportional to the amount of fuel delivered; a longer pulse width means more fuel injected.