1. start

8. NOTE: Distributor ignition ( DI ) is the term specified by the Society of Automotive Engineers (SAE) for an ignition system that uses a distributor. Electronic ignition ( EI ) is the term specified by the SAE for an ignition system that does not use a distributor.

17. Figure 56–4 Typical primary and secondary electronic ignition using a ballast resistor and a distributor. To protect the ignition coil from overheating at lower engine speeds, many electronic ignitions do not use a ballast resistor but use electronic circuits within the module. Continued

23. Figure 56–6 Operation of a typical pulse generator (pickup coil). At the bottom is a line drawing of a typical scope pattern of the output voltage of a pickup coil. The module receives this voltage from the pickup coil and opens the ground circuit to the ignition coil when the voltage starts down from its peak (just as the reluctor teeth start moving away from the pickup coil). Continued

28. Figure 56–10 Some Hall-effect sensors look like magnetic sensors. This Hall-effect camshaft reference sensor and crankshaft position sensor have an electronic circuit built in that creates a 0- to 5-volt signal as shown at the bottom. These Hall-effect sensors have three wires: a power supply (8 volts) from the computer (controller); a signal (0 to 5 volts); and a signal ground. Continued

30. Figure 56–11 A magnetic sensor uses a permanent magnet surrounded by a coil of wire. The notches of the crankshaft (or camshaft) create a variable magnetic field strength around the coil. When a metallic section is close to the sensor, the magnetic field is stronger because metal is a better conductor of magnetic lines of force than air. Continued

31. Figure 56–12 A typical magnetic crankshaft position sensor. Continued

32. Figure 56–13 (a) Typical optical distributor. (b) Cylinder I slit signals the computer the piston position for cylinder I. The I-degree slits provide accurate engine speed information to the computer.

34. Optical Distributors Do Not Like Light - Part 2 If this shield is not replaced during service, the signals are reduced and the engine may not operate correctly. This can be difficult to detect because nothing looks wrong during an inspection. Remember all optical distributors must be shielded between the rotor and the interrupter ring. Figure 56–14b A light shield being installed before the rotor is attached.

40. Figure 56–18 Wiring diagram of a typical Ford electronic ignition. Continued

42. Figure 56–19 Schematic of a Ford TFI-IV ignition system. The SPOUT connector is unplugged when ignition timing is being set. Continued

52. Figure 56–23 Typical Ford EDIS 4-cylinder ignition system. The crankshaft sensor, called a variable-reluctance sensor (VRS), sends crankshaft position and speed information to the EDIS module. A modified signal is sent to the computer as a profile ignition pickup (PIP) signal. The PIP is used by the computer to calculate ignition timing, and the computer sends a signal back to the EDIS module as to when to fire the spark plug. This return signal is called the spark angle word (SAW) signal.

61. Figure 56–26 A typical coil-on-plug (COP) ignition system on a V-8 with a separate coil for each cylinder. Continued

62. Figure 56–27 Individual coils with modules shown on the General Motors 4.2-L inline 6-cylinder light-truck engine. Note the aluminum cooling fins (heat sink) on top of each assembly. The vehicle computer controls the timing of the spark. Ignition timing also can be changed (retarded or advanced) on a cylinder-by-cylinder basis for maximum performance and to respond to knock sensor signals.

66. Figure 56–28 A DC voltage is applied across the spark plug gap after the plug fires and the circuit can determine if the correct air–fuel ratio was present in the cylinder and if knock occurred. Continued

77. Figure 56–33 The heat range of a spark plug is determined by the distance the heat has to flow from the tip to the cylinder head. Continued

83. end