Ignition Systems Questions and Answers

Answer: A

One coil serves two cylinders whose pistons rise together, so one fires the mixture and the other sparks harmlessly into exhaust gas. That halves the number of coils and needs no camshaft sensor for ignition purposes. Checking which component actually carries the load settles most questions of this kind at once. 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: B

Removing the cap, rotor and their tracking problems is the main gain. Coil energy does improve because each coil has more time to charge, which makes the second option a real accompanying benefit. Individual timing requires coil on plug. Tracing the requirement back to the physical constraint that produces it makes the answer follow. 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

One coil per cylinder allows the timing to be trimmed individually and simplifies misfire diagnosis. Removing the lead genuinely is a real benefit of the layout, which makes the last option a true statement of a secondary advantage. The shared behaviour explains why these belong together and the differences explain why both exist. Most errors here come from carrying across a result from a neighbouring case where it does not hold. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: D

The crankshaft sensor gives position twice per cycle, so a camshaft sensor is needed to say which revolution is which. The missing tooth genuinely identifies angular position, which makes the second option half right and therefore tempting. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Naming what changes and what stays the same is the reliable route through questions of this shape.

Answer: A

The sixty minus two wheel gives six degree resolution with a recognisable gap for reference. Thirty six minus one is genuinely another common pattern, which makes the last option a correct description of a real alternative. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. 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

Without a crankshaft signal the controller does not know where the engine is and will not fire the coils or injectors. Intermittent sensors genuinely do cause cutting out and rough running, which makes the last option a real symptom of a failing rather than failed sensor. 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

Combustion takes roughly the same time whatever the speed, so the spark must occur earlier in crank degrees as speed rises. Load affects timing too but in the opposite sense, which makes the last option describe a real relationship inverted. Naming what changes and what stays the same is the reliable route through questions of this shape. The order in which the effects act is what decides the outcome, so it is worth establishing first. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: D

Bob weights flew outward against springs and rotated the cam relative to the shaft. The vacuum capsule provided load related advance, which makes the second option a real mechanism serving the other variable. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. 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.

Answer: A

High depression means light load and a lean, slow burning charge that needs more advance. Throttle position and manifold depression are closely related, which makes the last option a plausible description of the same information by another route. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. The shared behaviour explains why these belong together and the differences explain why both exist.

Answer: B

A dilute charge at light load burns slowly, so the spark must occur earlier for the pressure peak to arrive at the right moment. That is the whole basis of vacuum advance. Full load needs less advance and risks detonation. The order in which the effects act is what decides the outcome, so it is worth establishing first. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Reading the definition literally, rather than recalling a summary, avoids the usual confusion.