Engine Performance Flashcards
7 cards from real NAPA 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 flashcards as text
A hot engine pings during acceleration. Which sensor lets the PCM retard timing to stop it?
Answer: Knock sensor
The piezoelectric knock sensor detects detonation vibrations so the PCM can retard spark timing.
An engine cranks but will not start, and the tachometer reads zero while cranking. Which sensor is the most likely failure?
Answer: Crankshaft position sensor
Without a crank position signal, the PCM sees no rpm and will not fire injectors or coils.
When testing a coil-on-plug ignition coil, the most effective way to confirm a misfire follows the coil is what?
Answer: Swap the coil to another cylinder and see if the misfire moves
If the misfire code moves to the new cylinder with the coil, the coil is confirmed faulty.
A spark plug with dry, black, sooty deposits most likely indicates what?
Answer: Rich mixture or weak spark
Dry carbon fouling is caused by a rich mixture, excessive idling, or weak ignition.
A spark plug with blistered white insulator and melted electrodes indicates which condition?
Answer: Overheating from lean mixture or overadvanced timing
Blistering and melted electrodes indicate excessive combustion temperature, often from lean mixture, advanced timing, or wrong heat range.
Which reading on an ignition scope's firing line usually indicates high secondary resistance, such as an open plug wire?
Answer: Very high firing voltage with a short spark line
High resistance in the secondary circuit takes more voltage to jump and leaves less energy for spark duration.
A cam/crank correlation code (such as P0016) on a newly timed engine most likely means what?
Answer: Timing belt or chain installed one or more teeth off
P0016 means the cam and crank signals are out of expected alignment, often from incorrect timing belt or chain installation.