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
A technician sees misfire counts accumulating on cylinder 3 only under high load. Which data parameter would BEST differentiate between a fuel injector problem and an ignition coil problem?
Answer: Injector pulse width combined with ignition timing data for that cylinder
Comparing injector pulse width (fuel delivery) and ignition event data for the specific cylinder isolates whether the fault is fuel or spark-related.
During data logging, a CPT technician notices the boost pressure overshoots the target by 4 psi before the wastegate corrects it. What system is most responsible for controlling this response?
Answer: The boost pressure control solenoid and ECU wastegate duty cycle mapping
Boost control solenoid duty cycle and ECU wastegate maps determine how quickly the wastegate opens to regulate boost pressure.
What does a rapidly oscillating O2 sensor waveform between 0.1V and 0.9V in closed-loop operation indicate about the fuel control system?
Answer: Normal active closed-loop fuel control maintaining stoichiometric AFR
Rapid switching between rich and lean signals (0.1V–0.9V) indicates the ECU is correctly adjusting fuel delivery in closed-loop to maintain stoichiometric AFR.
When reviewing dyno pull data, a technician sees consistent power loss at the same RPM point across multiple runs. What should be investigated first?
Answer: A repeatable event such as fuel cut, ignition retard, or shift point activation at that RPM
A consistent power loss at the same RPM across multiple runs points to a programmed event such as a rev limiter, fuel cut, or timing pull triggering at that point.
A performance technician uses a pressure transducer in the cylinder to generate a pressure-volume (PV) diagram. A 'lazy' S-curve with a rounded peak indicates what combustion issue?
Answer: Slow flame front propagation, potentially due to over-retarded ignition timing
A rounded, lazy peak on the PV diagram indicates the pressure rise is too slow, commonly caused by retarded ignition timing or a slow-burning mixture.
What does it mean when catalyst efficiency monitor data shows an upstream and downstream O2 sensor oscillating at nearly identical frequency?
Answer: The catalytic converter has degraded and is no longer storing oxygen effectively
When the downstream O2 sensor mimics the upstream sensor's switching pattern, the catalyst is no longer buffering oxygen fluctuations, indicating converter failure.