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Difficulty: MediumIgnition System

In an automotive electronic ignition system, a sequence of electrical and magnetic events must occur to generate and deliver spark to the cylinder. In what chronological order do these events occur during a single ignition cycle?

  1. 1The crankshaft position sensor detects engine rotational position and sends a timing pulse to the engine control module.
  2. 2The engine control module interrupts the ground path to open the ignition coil's primary circuit.
  3. 3The primary magnetic field collapses rapidly across the secondary coil windings, inducing tens of thousands of volts.
  4. 4High-voltage electrical current arcs across the spark plug electrode gap to ignite the air-fuel mixture.

Answer

The correct sequence begins with the crankshaft position sensor detecting rotational position, followed by the control module opening the primary circuit, which causes the primary magnetic field to collapse and induce high voltage, ending with the high-voltage arc across the spark plug gap.
The ignition process always proceeds from sensor detection to primary circuit interruption, followed by mutual induction in the secondary coil, and ends with the spark plug discharge.

Step-by-Step Solution

1
Identify the initial timing trigger.
The crankshaft position sensor signals the engine control module with accurate crankshaft angle data.
The ignition cycle must establish precise piston location before timing calculations can be executed.
2
Determine the switching action that initiates high voltage.
The control module de-energizes the primary circuit switching transistor, interrupting primary current flow.
A steady DC current in the primary winding creates a magnetic field; breaking this current causes the field to collapse.
3
Trace the step-up voltage induction.
The collapsing magnetic field cuts through the secondary windings, inducing high voltage via mutual induction.
The ratio of secondary to primary wire turns multiplies the initial 12-volt battery power into 20,000 to 50,000 volts.
4
Identify the final delivery of electrical energy.
High-voltage electricity travels to the spark plug and jumps the air gap between the center and ground electrodes.
The electrical arc creates the thermal energy required to ignite the compressed gasoline and air mixture.

Key Concept

Electronic ignition timing triggering, primary circuit interruption, and secondary high-voltage mutual induction.
Estimated Time:1m 0s
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Topics

Ignition System

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