General Engine Diagnosis Flashcards
6 cards from real ASE4 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 General Engine Diagnosis flashcards as text
A technician performs a relative compression test using a scan tool. Which data parameter is monitored?
Answer: Cranking RPM variation per cylinder
A relative compression test measures the variation in cranking RPM as each cylinder comes up on compression stroke.
Blue smoke from the exhaust under hard acceleration most likely indicates:
Answer: Worn piston rings allowing oil consumption
Blue smoke under acceleration is caused by worn rings that allow oil to be drawn into the combustion chamber under high vacuum.
A vacuum gauge shows a reading that slowly drops and then rises at idle. This indicates:
Answer: A restricted exhaust system
A vacuum reading that gradually drops then rises indicates a restricted exhaust is causing backpressure to build and release.
An engine produces a loud knock only when cold that disappears after warm-up. This is MOST likely:
Answer: Piston slap due to worn pistons
Piston slap is common when pistons are cold and contracted, creating excess clearance in the bore that diminishes as the engine warms.
When diagnosing an oil consumption complaint, the FIRST step is to:
Answer: Check for external oil leaks and confirm actual consumption
External oil leaks must be ruled out first before assuming internal consumption is the cause of low oil level.
A steady vacuum reading of 17–21 in-Hg at idle is considered:
Answer: Normal for a healthy engine at sea level
A steady 17–21 in-Hg vacuum reading at idle indicates a healthy, well-tuned engine at sea level.