ASE Ignition Systems 3

Question 1

What defines a coil-on-plug (COP) ignition system?

Accepted Answer

A dedicated ignition coil is mounted directly on each individual spark plug

Answer

In a COP system, each cylinder has its own coil mounted directly over its spark plug, eliminating all high-voltage spark plug wires and minimizing energy loss.

Question 2

A weak or intermittent spark condition would most likely be caused by:

Accepted Answer

A failing ignition coil with a degraded secondary winding

Answer

A failing ignition coil with weakened secondary insulation or poor winding integrity cannot generate sufficient voltage, producing weak or intermittent spark and engine misfires.

Question 3

What was the purpose of the ballast resistor in older ignition systems?

Accepted Answer

To limit primary coil current during normal operation to prevent coil overheating

Answer

The ballast resistor dropped voltage to the coil during normal running to prevent thermal damage, while being bypassed during cranking to provide full voltage and a hotter spark.

Question 4

On a secondary ignition oscilloscope pattern, what does an abnormally HIGH firing line indicate?

Accepted Answer

High resistance in the secondary circuit requiring more voltage to fire

Answer

A high firing line means extra voltage was needed to jump the spark gap, indicating high resistance from worn plug electrodes, an excessively wide gap, or damaged secondary wiring.

Question 5

What is the minimum spark duration generally considered necessary for reliable combustion?

Accepted Answer

0.5 milliseconds

Answer

A minimum of approximately 0.5 milliseconds (500 microseconds) of spark duration is generally required to reliably ignite the air-fuel mixture, especially under lean or diluted conditions.

ASE - Automotive Service Excellence Certified Tech Practice Test

ASE - Automotive Service Excellence Certified Tech Practice Test

ASE Ignition Systems 3