GM Service Manual Online
For 1990-2009 cars only

Ignition System Description Coil Ignition

Ignition System Description

This system uses a separate coil for each engine cylinder. This provides for maximum spark energy availability for higher winding engines. At 10,000 RPM on a 4-cylinder engine, there is only 0.030 seconds per spark available. The coil only has a micro amount of time to build up energy and to dissipate the energy which is equally important. Timing and dwell are controlled by the vehicle's engine controller.

The coil at the plug ignition is an electronic engine-sensing and spark control system that operates electronically, not mechanically. Like direct ignition system (DIS), the system has no moving parts and does not require a timing adjustments.

The package includes .

    • Coil for each cylinder.
    • Dose not require timing adjustment.
    • Package includes a coil for each cylinder.
    • Electronic coil driver for each coil.
    • Driver mounted directly on the coil.
    • Crankshaft position sensors.
    • Camshaft position sensor.

Highest efficiency and lowest electromagnetic radiation is attained by mounting the coils in close proximity to the spark plugs. Unlike the DIS, waste spark is eliminated because of the coil per cylinder concept. Eliminating the waste spark along with high efficiency spark plugs results in 3 times higher energy delivered to the cylinder combustible mixture while drawing the same power from the vehicle's electrical system. Higher energy delivered results in cleaner and more consistent combustion needed for meeting the OBD II system requirements. CPC systems are known as up integrated because the systems are totally dependent on the engine controller for timing information. Sensor information is sent directly to the engine controller which results in an ignition system that is functioning before the engine rotates 180 degrees due to the CPC system architecture.

Highlights

  1. Reduced RFI emissions
  2. Full encapsulated composite iron core
  3. Programmable energy capable
  4. Ramp and fire dwell capable
  5. Efficient energy delivery
  6. Internal over dwell protection (current trip)

Ignition Coil


Object Number: 260177  Size: SH

There are 2 different manufacturers for the ignition coils, Melco ® (1) (square design), and Delphi ® (2) (round design). These 2 coils use 2 different spark plug wire, and mounting brackets.

Spark Plug Wire Length


Object Number: 340933  Size: SH

The Melco ® (1) (square design) uses a spark plug wire that is 145 mm length cable seal to cable seal.

The Delphi ® (2) (round design) uses a spark plug wire that is 110 mm length cable seal to cable seal.

Mounting Bracket


Object Number: 260077  Size: SH

Melco ® (1) (square design).

Delphi ® (2) (round design).

Ignition System Description High Voltage System

Distributor Ignition (DI)

Notice: The distributor used with the OBD II ignition system is located in a fixed, non-adjustable position. Do not adjust the engine base timing by rotating this distributor. Otherwise, crossfiring and damage to the distributor will result.

These ignition systems consist of a distributor with the following components:

    • Camshaft position (CMP) sensor
    • Separate ignition coil with sealed connectors
    • Secondary ignition wires
    • Spark plugs
    • Knock sensor (KS)
    • Crankshaft position (CKP) sensor

The ignition system is controlled by the Vehicle Control Module (VCM). The VCM monitors information from various engine sensors. The VCM computes the desired spark advance timing, and controls the dwell. The VCM also controls the firing of the ignition coil via an ignition control line to the coil driver.