EETC EETC - Equipment & Engine Training Council Ignition Systems and Spark Technology Questions and Answers 1 — Questions and Answers
Question 1: What is the primary function of the ignition coil in a small engine?
- Step up low battery voltage to high voltage needed to fire the spark plug (Correct answer)
- Regulate fuel delivery timing
- Control valve timing
- Filter electrical noise from the charging system
Correct answer: Step up low battery voltage to high voltage needed to fire the spark plug
The ignition coil transforms low primary voltage into the high-voltage spark (typically 20,000–40,000 volts) needed to jump the spark plug gap and ignite the air-fuel mixture.
Question 2: On a magneto-based ignition system, what component triggers spark at the correct crankshaft position?
- Battery
- Points or electronic trigger module aligned with the flywheel magnets (Correct answer)
- Carburetor float
- Governor spring
Correct answer: Points or electronic trigger module aligned with the flywheel magnets
Breaker points or an electronic trigger module detect the passing of flywheel magnets and signal the coil to collapse its magnetic field and fire the spark plug.
Question 3: What is the correct method for measuring spark plug gap on a small engine?
- Visual inspection only
- Wire-type feeler gauge inserted between center and ground electrode (Correct answer)
- Flat feeler gauge slid between electrodes
- Gap is factory-set and never needs checking
Correct answer: Wire-type feeler gauge inserted between center and ground electrode
A wire-type feeler gauge provides an accurate measurement of the spark plug gap because the rounded wire matches the curved electrode shape better than a flat gauge.
Question 4: What does a black, sooty spark plug indicate about engine combustion?
- Lean fuel mixture
- Rich fuel mixture or oil fouling (Correct answer)
- Correct air-fuel ratio
- Ignition timing is too advanced
Correct answer: Rich fuel mixture or oil fouling
Black, sooty deposits on a spark plug indicate excess unburned carbon from a rich fuel mixture or oil entering the combustion chamber.
Question 5: What is ignition timing advance, and why is it necessary?
- Firing the spark plug before top dead center to allow full combustion pressure at the power stroke (Correct answer)
- Delaying spark until after TDC to prevent detonation
- Increasing spark voltage for cold starts
- Retarding timing to reduce NOx emissions only
Correct answer: Firing the spark plug before top dead center to allow full combustion pressure at the power stroke
Spark is fired before TDC so the combustion event reaches peak pressure just after TDC, maximizing the force applied to the piston during the power stroke.
Question 6: What is the air gap specification between the ignition coil armature and flywheel magnets used for?
- Controlling fuel metering
- Setting the magnetic coupling distance for proper coil charging and spark energy (Correct answer)
- Adjusting valve clearance
- Setting carburetor float height
Correct answer: Setting the magnetic coupling distance for proper coil charging and spark energy
The air gap between the coil armature and flywheel magnets controls how strongly the magnets induce current in the coil, directly affecting spark energy output.
EETC EETC - Equipment & Engine Training Council Ignition Systems and Spark Technology Questions and Answers 1
What is the primary function of the ignition coil in a small engine?