Ignition Systems Questions and Answers

Answer: C

Advancing too far raises the peak pressure and the end gas detonates, producing the characteristic knock. Pre-ignition is a genuinely related but distinct phenomenon caused by a hot spot rather than by timing, which is why the second option is a near miss. 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: D

Detonation is the spontaneous ignition of the end gas after the flame front has started, while pre-ignition ignites the charge before the spark arrives. Pre-ignition genuinely is quieter and more destructive, which makes the last option a real observation. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: A

A piezoelectric sensor on the block hears the characteristic ringing and the controller retards until it stops. Cylinder pressure sensors genuinely exist on some engines, and a knock sensor is itself an accelerometer, which makes both alternatives partly true. The shared behaviour explains why these belong together and the differences explain why both exist. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: B

Timing is retarded on the offending cylinder then advanced again gradually to find the limit. Enrichment genuinely is used as an additional measure at high load, which makes the second option a real if partial description. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: C

Heavy load, poor fuel and high temperature all push the end gas towards spontaneous ignition. A rich mixture actually suppresses detonation, which is why enrichment is used as a countermeasure at full load. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: D

Octane rating measures resistance to spontaneous ignition under pressure. Cetane number is the diesel measure of the opposite property, ignition readiness, which makes the second option a real measure from the wrong fuel. Most errors here come from carrying across a result from a neighbouring case where it does not hold. The order in which the effects act is what decides the outcome, so it is worth establishing first. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: A

Modern engines protect themselves by retarding, at the cost of power and economy. On an engine without a knock sensor the damage would indeed be real, which makes the second option true of an older vehicle. Naming what changes and what stays the same is the reliable route through questions of this shape. Checking which component actually carries the load settles most questions of this kind at once. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: B

A stroboscopic timing light freezes the pulley mark against a scale on the timing cover. A dial gauge genuinely locates top dead centre for static timing, which makes the last option a real technique for a related purpose. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: C

Base timing is quoted at a specified speed with the vacuum pipe removed and plugged on many engines. Running at operating temperature genuinely is specified too, which makes the last option a real part of the same procedure. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. The order in which the effects act is what decides the outcome, so it is worth establishing first.

Answer: D

Slackening the clamp and turning the body advances or retards the whole map. Changing the point gap does shift the timing as a side effect, which makes the second option a real if incorrect method of adjustment. The order in which the effects act is what decides the outcome, so it is worth establishing first. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Checking which component actually carries the load settles most questions of this kind at once.