Ignition Systems Questions and Answers

Answer: A

Too little dwell leaves the coil undercharged and the engine misfires at high speed, which was the characteristic weakness of a contact breaker system. Electronic modules hold the dwell constant in time rather than in degrees. Checking which component actually carries the load settles most questions of this kind at once. The order in which the effects act is what decides the outcome, so it is worth establishing first. The quantity that varies and the quantity that does not are worth naming before any substitution is attempted.

Answer: B

Blistering means too hot, dry soot means too rich or too cold, and a wet film means oil is getting past the rings or the valve stem seals. Reading plugs remains a quick and useful diagnostic. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Checking which component actually carries the load settles most questions of this kind at once. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: C

A magneto generates its own energy from a rotating magnet and needs no external supply, which suits mowers and chainsaws. Flywheel generators feeding a coil are genuinely used and are closely related, which makes the last option a real arrangement. The shared behaviour explains why these belong together and the differences explain why both exist. Tracing the requirement back to the physical constraint that produces it makes the answer follow.

Answer: D

A capacitor is charged to several hundred volts and dumped into the coil primary, giving a very fast rising spark. Inductive systems store energy in the coil field, which is precisely the distinction and makes the second option a correct description of the alternative. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: A

The rapid rise outruns leakage through deposits, which is why such systems suit two strokes and racing engines. Its weakness is a short spark duration, so the second option describes exactly what it does not offer. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: B

The spark lasts a fraction of the time an inductive system gives, which can leave a lean or stratified charge unignited. High speed operation is actually a strength. Multi-spark strategies compensate for the short duration. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Checking the units of each quantity catches a wrong formula before the arithmetic begins.

Answer: C

Multi-spark discharge fires repeatedly at low speed, giving several chances to ignite a difficult charge. Advancing the timing genuinely gives more time for combustion, which makes the last option a real if different measure. Naming what changes and what stays the same is the reliable route through questions of this shape. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Checking the units of each quantity catches a wrong formula before the arithmetic begins.

Answer: D

Igniting a small rich cloud in a mostly lean cylinder needs energy, timing precision and often several sparks. Plug position and gap genuinely are optimised for the charge cloud, which makes the last option a real design consideration. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Naming what changes and what stays the same is the reliable route through questions of this shape. Reading the definition literally, rather than recalling a formula, is the reliable route through questions of this shape.

Answer: A

Projecting the tip into the charge places the spark where the mixture is, and the incoming charge cools it. Surface discharge plugs genuinely exist for very heavily fouling applications, which makes the last option a real design rather than an invention. Checking which component actually carries the load settles most questions of this kind at once. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: B

Platinum and iridium plugs commonly run a hundred thousand kilometres or more. Forty thousand is genuinely typical of a conventional plug, which makes the last option a correct figure for the other type. Leaded fuel required very frequent changes. Tracing the requirement back to the physical constraint that produces it makes the answer follow. The order in which the effects act is what decides the outcome, so it is worth establishing first.