Ignition Systems Questions and Answers

Answer: C

A hundred thousand kilometres of heat cycling bonds the thread to the head, particularly in aluminium. Reach genuinely affects how much thread is exposed to combustion, which makes the last option a real contributing factor. The shared behaviour explains why these belong together and the differences explain why both exist. Checking which component actually carries the load settles most questions of this kind at once.

Answer: D

A very light anti-seize is permitted by some manufacturers with a reduced torque, while others forbid it. Many plugs are supplied with a plating that makes it unnecessary, which is why fitting dry is genuinely correct for those. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Tracing the requirement back to the physical constraint that produces it makes the answer follow.

Answer: A

Lubrication reduces friction so the same torque produces far more clamping load. Heat transfer through a contaminated seat genuinely is impaired, which makes the last option a real secondary concern of the same error. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: B

Flat seat plugs use a captive crush washer while taper seat plugs seal on the cone and need none. Fitting a washered plug where a taper is required, or the reverse, changes the reach and can wreck the engine. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: C

Too long a reach can strike the piston, and too short leaves exposed thread that carbons and seizes. Heat path genuinely changes as well, which makes the last option a real consequence. Reach must match the head exactly. 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 summary, avoids the usual confusion.

Answer: D

A slim pencil coil fits into the plug well and contacts the plug directly through a spring and boot. Igniter transistors genuinely are built into many such coils, which makes the last option a real component often integrated with it. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Most errors here come from carrying across a result from a neighbouring case where it does not hold.

Answer: A

Oil attacks the rubber and provides a tracking path to earth, which produces a misfire on that cylinder. Vibration and age genuinely crack boots as well, which makes the last option a real failure mechanism of the same part. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: B

Fitting a new coil into an oil filled well simply destroys it, so the leak is cured first. Renewing the plug genuinely is sensible because a worn plug raises the demand on the coil, which makes the last option good practice stated too absolutely. The order in which the effects act is what decides the outcome, so it is worth establishing first. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: C

A calibrated gap tester shows whether the coil can produce the voltage needed under load. Resistance measurements genuinely find open and shorted windings, which makes both electrical options real tests that simply cannot reveal breakdown under voltage. 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.

Answer: D

A dedicated tester keeps the operator away from the voltage and gives a repeatable gap. Disabling injection genuinely protects the catalyst during prolonged cranking, which makes the last option a real and sensible additional precaution. 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.