CPT Ignition Systems & Timing 2

Question 1

What is dwell angle in a conventional points-type ignition system?

Accepted Answer

The number of degrees the distributor cam rotates while the points remain closed

Answer

The number of degrees the crankshaft rotates between spark events

Answer

The angle at which the distributor rotor aligns with the cap terminal

Answer

The degrees of vacuum advance applied at cruise conditions

Question 2

What advantage does a coil-on-plug (COP) ignition system offer over a conventional single-coil system?

Accepted Answer

Each cylinder gets a dedicated coil, providing maximum energy and faster recharge time

Answer

COP systems require a shared secondary wire harness for simplified wiring

Answer

COP systems eliminate the need for a crankshaft position sensor

Answer

COP systems use lower voltage to reduce insulation requirements

Question 3

What is the primary role of a crankshaft position sensor (CKP) in a modern ignition system?

Accepted Answer

To provide the ECU with engine speed and piston position data for spark timing

Answer

To measure exhaust backpressure for timing correction

Answer

To signal the fuel pump relay when cranking

Answer

To measure crankshaft endplay for bearing wear detection

Question 4

How does pre-ignition differ from detonation?

Accepted Answer

Pre-ignition occurs before the spark fires; detonation occurs after the spark fires

Answer

Pre-ignition is caused by lean mixtures; detonation is caused by rich mixtures

Answer

Pre-ignition only occurs at idle; detonation only occurs under full load

Answer

Pre-ignition is harmless; detonation always causes immediate engine damage

Question 5

How does higher altitude generally affect ignition timing requirements?

Accepted Answer

Higher altitude typically requires more advanced timing due to lower air density and slower flame speed

Answer

Higher altitude requires more retarded timing due to increased oxygen density

Answer

Altitude has no measurable effect on optimal ignition timing

Answer

Higher altitude requires timing retard to compensate for increased detonation risk

Question 6

What is the primary function of a knock sensor in a modern engine management system?

Accepted Answer

To detect detonation and signal the ECU to retard ignition timing

Answer

To detect valve train noise and alert the driver via the check engine light

Answer

To monitor combustion chamber pressure for misfire detection

Answer

To adjust fuel trim in response to exhaust oxygen levels

Question 7

Why is the firing order of an engine important for performance technicians?

Accepted Answer

It ensures that power strokes are evenly spaced to minimize vibration and heat buildup in adjacent cylinders

Answer

It determines the oil viscosity required for proper lubrication

Answer

It sets the maximum RPM limit of the engine

Answer

It defines the sequence in which valves open relative to the camshaft lobe profile