Ignition Systems Questions and Answers

Answer: A

Helical or solid inserts restore the thread without removing the head on many engines. Oversize self tapping plugs genuinely exist as a repair, which makes the last option a real product rather than an invention. 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. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: B

The controller watches the crankshaft accelerate after each firing and identifies the cylinder that contributes nothing. Lambda sensors genuinely detect the resulting excess oxygen but cannot identify which cylinder on most engines. Tracing the requirement back to the physical constraint that produces it makes the answer follow. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. The quantity that varies and the quantity that does not are worth naming before any substitution is attempted.

Answer: C

P0300 is a random misfire and P0301 upward identify the cylinder. A misfire genuinely can set a lean code because unburnt oxygen reaches the sensor, which makes the last option a real secondary consequence. The shared behaviour explains why these belong together and the differences explain why both exist. 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: D

Unburnt fuel ignites in the catalyst and melts it, which is why the misfire lamp flashes. Coil failure genuinely follows from a persistently open circuit secondary, which makes the last option a real accompanying risk. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. 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: A

A flashing lamp means stop or reduce load immediately to save the catalyst. A steady lamp is the ordinary emissions warning. The distinction between steady and flashing is one every driver should know. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. 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.

Answer: B

Primary resistance is a fraction of an ohm to a few ohms between the two small terminals. Measuring to the tower gives the secondary resistance, which makes the second option a real measurement of the other winding. Most errors here come from carrying across a result from a neighbouring case where it does not hold. The shared behaviour explains why these belong together and the differences explain why both exist. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: C

Secondary windings measure from around five to twenty thousand ohms depending on the design. Low resistance belongs to the primary. Infinity means an open circuit winding and a failed coil. Naming what changes and what stays the same is the reliable route through questions of this shape. 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: D

A coil can measure correctly and still break down at twenty thousand volts when hot. That is why a coil that passes a meter test may still misfire under load. Oscilloscope or spark testing is more revealing. 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. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: A

The secondary waveform shows firing voltage, burn time and the condition of the whole circuit. A calibrated gap tester genuinely gives a useful practical check, which makes the last option a real if cruder tool. 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. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.

Answer: B

A wide gap needs more voltage to break down, which raises the firing line. Burn time genuinely shortens as firing voltage rises because the energy is fixed, which makes the second option a real accompanying observation. The order in which the effects act is what decides the outcome, so it is worth establishing first. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.