Ignition Systems Questions and Answers

Answer: C

Points blacken and pit quickly and the spark is feeble. Complete failure to spark does occur in severe cases, which makes the second option the end state described with the wrong explanation. Checking which component actually carries the load settles most questions of this kind at once. 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: D

Dwell is the period during which primary current builds, and too little leaves the coil insufficiently charged. Ignition timing is the separate quantity describing when the spark occurs. Dwell and point gap vary inversely. Tracing the requirement back to the physical constraint that produces it makes the answer follow. 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.

Answer: A

Opening the points wider makes them separate earlier and close later, reducing the closed period. Cam profile does set the maximum possible dwell, which makes the last option partly true. Setting one sets the other. The shared behaviour explains why these belong together and the differences explain why both exist. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: B

There is less time per cycle at speed, so a short dwell leaves the coil undercharged and the engine misfires. That is the classic high speed misfire of a points system. Electronic systems control dwell actively. 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. A symptom that appears under one condition and not another is what narrows the diagnosis quickly.

Answer: C

The module closes the circuit a fixed time before the spark, so the coil is always fully charged and never overheated. Timing accuracy genuinely improves too, which makes the last option a real accompanying benefit of the same change. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming what changes and what stays the same is the reliable route through questions of this shape. Working one numerical case through both cases side by side fixes the distinction better than any rule of thumb.

Answer: D

Reluctor and Hall sensors in the distributor triggered the module without contacts to wear. Crankshaft sensors came with distributorless ignition, which makes the last option correct for a later generation. Optical triggers genuinely were used by some manufacturers. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.

Answer: A

A coil and magnet produce a voltage as the reluctor teeth pass, and the amplitude grows with speed. A Hall sensor gives a square wave of constant amplitude, which makes the second option a correct description of the other sensor type. Naming what changes and what stays the same is the reliable route through questions of this shape. 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: B

A Hall sensor is an active device with three wires: supply, earth and signal. A reluctor pickup is passive and generates its own signal, which is precisely the distinction between them and shows in the connector. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. The order in which the effects act is what decides the outcome, so it is worth establishing first. A single measurement chosen to respond to the one asymmetry beats several that respond to shared behaviour.

Answer: C

Hall output does not depend on speed, so it works at the slowest cranking. Reluctor output falls away at low speed. The simplicity argument belongs to the reluctor, which needs no supply at all. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. 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: D

Distributorless systems use one coil per pair of cylinders and fire them together, removing the rotating high voltage parts. Coil on plug is the further development of the same idea, which makes the last option a real system rather than a wrong one. The order in which the effects act is what decides the outcome, so it is worth establishing first. The shared behaviour explains why these belong together and the differences explain why both exist.