Distributorless Ignition Systems: Advancements in Spark Delivery

Distributorless ignition systems (DIS) have revolutionized the way spark is delivered to the engine cylinders. By eliminating the traditional distributor, these systems offer improved reliability, precise spark timing, and enhanced engine performance. In this article, we will explore two types of distributorless ignition systems: the Wasted Spark Type and the Coil over Plug Type (including the Multi-Coil over Plug Type). We will delve into their components, operation, and advantages, showcasing the advancements in spark delivery technology.

Wasted Spark Type:

The Wasted Spark Type ignition system is a common variant of the distributorless ignition system. It employs a coil pack or ignition module and uses a single coil to supply spark to two cylinders simultaneously. The components of the Wasted Spark Type system include:

  1. Coil Pack/Ignition Module: The coil pack or ignition module houses multiple ignition coils, each connected to two spark plugs—one for the compression stroke and the other for the exhaust stroke.
  2. Ignition Coils: The ignition coils in the Wasted Spark Type system are responsible for generating the high-voltage spark needed to ignite the air-fuel mixture. Each coil supplies spark to two cylinders simultaneously—one with compressed fuel-air mixture and the other with residual gases in the exhaust stroke.

Operation of the Wasted Spark Type System:

  1. Cylinder Firing: During the compression stroke, the spark plug in one cylinder receives the spark, igniting the air-fuel mixture and powering the engine.
  2. Wasted Spark: Simultaneously, on the exhaust stroke of a neighboring cylinder, the spark plug receives a spark. Since there is no air-fuel mixture to ignite, this spark is considered “wasted.” It ensures that the residual gases are burned off in the exhaust stroke, improving emissions.

Advantages of the Wasted Spark Type System:

  1. Simplicity: The Wasted Spark Type system eliminates the need for a distributor and reduces the number of ignition components required, simplifying the overall ignition system design.
  2. Cost-Effective: The use of a single coil for two cylinders reduces the number of ignition coils required, resulting in cost savings.

Coil over Plug Type (including Multi-Coil over Plug Type):

The Coil over Plug (COP) Type ignition system takes the distributorless concept further by employing an individual ignition coil for each cylinder. The Multi-Coil over Plug Type system, as an advanced variation, employs multiple coils for each cylinder, enabling even more precise spark control. The components of the Coil over Plug and Multi-Coil over Plug Type systems include:

  1. Ignition Coils: In the COP Type system, each cylinder has its dedicated ignition coil mounted directly over its corresponding spark plug. In the Multi-Coil over Plug Type system, multiple coils may be used for each cylinder, depending on the engine design.
  2. Engine Control Unit (ECU): The ECU, the brain of the ignition system, controls the timing and duration of spark delivery to each individual coil based on inputs from various engine sensors.

Operation of the COP and Multi-Coil over Plug Type Systems:

  1. Sensor Inputs: The ECU receives inputs from sensors such as the crankshaft position sensor, camshaft position sensor, and throttle position sensor to determine the optimal timing for spark delivery.
  2. Individual Coil Control: The ECU sends individual signals to each ignition coil, precisely controlling the timing and duration of spark generation for each cylinder.
  3. Spark Generation: The ignition coil(s) receive the signal from the ECU, generating a high-voltage spark at the spark plug(s) to ignite the air-fuel mixture in each cylinder.

Advantages of the COP and Multi-Coil over Plug Type Systems:

  1. Precise Spark Control: The individual coil control allows for precise spark timing and duration, optimizing combustion efficiency and engine performance.
  2. Improved Reliability: With separate coils for each cylinder, the COP and Multi-Coil over Plug Type systems offer enhanced reliability, as a failure in one coil does not affect the entire ignition system.
  3. Faster Spark Rise Time: The direct coil-to-spark plug configuration in both systems reduces energy losses and improves spark rise time, leading to improved combustion efficiency.
  4. Enhanced Engine Performance: The precise spark control, faster spark rise time, and efficient combustion contribute to improved engine performance, including power output, fuel efficiency, and emissions reduction.


Distributorless ignition systems, such as the Wasted Spark Type, Coil over Plug Type, and Multi-Coil over Plug Type, have ushered in advancements in spark delivery technology. These systems offer improved reliability, precise spark control, and enhanced engine performance compared to traditional distributor-based systems. As automotive technology continues to evolve, distributorless ignition systems play a pivotal role in optimizing combustion efficiency, fuel economy, and emissions reduction, driving the future of engine ignition.