Terminology
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Ignition Systems - History

During the first 50 years from the 1920's to the 1970's, engines were equipped with point-type ignition systems that did not change much. In the 1970's electronic ignition systems were introduced, but these systems still had distributor advances. During the late 1970's and early 1980's electronic ignition systems were introduced with computer-controlled spark advance. In the mid-1980's, Electronic Ignition (EI) systems were introduced with no distributors and computer-controlled spark advance. In the 1990's many engines are equipped with EI systems, and continue to change dramatically.

Common Ignition Systems
1. Conventional
2. Distributor (Electronic)
- Mechanical and vacuum timing advance or
- Electronic spark timing
3. Electronic (Distributorless)

The main task of an ignition system is to provide a precisely timed spark with sufficient current to ignite the proper fuel to air mixture. Regardless of any type of system, any ignition must have the following elements:

  • Adequate Electrical Supply - this is the vehicle's battery, which supplies the initial current to startup the vehicle.
  • An Ignition Coil capable of augmenting 12 to 14 volts to 6,000 to 35,000 volts
  • Distribution of secondary voltage
  • Electrical wiring to distribute secondary current from the ignition coil to the spark plugs
  • Spark Plugs to create the spark that ignites the air/fuel mixture

The Distributorless (Electronic) Ignition System

Introduction
The distributorless ignition system has been around for the last decade. It was designed to replace the mechanical distributor system (HEI) in controlling the ignition secondary coil voltage. This system is comprised of the following components:

  • Crankshaft Timing Sensor: located in the front of the crankshaft to trigger the ignition system. This sensor consists of a single Hall effect magnetic switch activated by 3 vanes on the crankshaft damper and pulley assembly. This sensor sends a signal that feeds timing and RPM information to the DIS and computer module.
  • Camshaft Sensor: it is driven by the camshaft and provides information on the cylinder position for the ignition coil and fuel system
  • Ignition (DIS) Module: it receives the signal from the crankshaft sensor and the camshaft sensor. It also receives the spark signal from the vehicle's central computer. Its major purpose is to use the information supplied to it to control the ignition coils. The reason it does this is to ensure that they fire in the correct sequence. The DIS module also controls the engine dwell.
  • Ignition Coil Pack: it is comprised of multiple ignition coils. The DIS module controls these coils by means of coil leads. The ignition coils fire two spark plugs simultaneously; one on the compression stroke and one on the exhaust stroke.
The main advantage with this system was that it provided improved economy and performance with reduced emissions. Other advantages included:
  • Fewer moving parts (less parts to replace)
  • More compact mounting
  • Elimination of mechanical timing adjustments
  • Less maintenance
  • More coil cool down between firing events
 

 


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