Chapter 35 PowerPoint

Define these Technical Terms using the textbook:

1. dead cylinder

2. ignition primary voltage test

3. misfire code

4. over-advanced ignition timing

5. retarded ignition timing

6. secondary wire resistance test

7. spark test

8. spark tester

Answer these discussion questions using the textbook:

1. Name some common tests used to find ignition system troubles.

Read the chapter summary below:

■ Problems caused by spark plugs, secondary wires, ignition coils, ECMs, and related wiring manifest themselves in a variety of ways.

■ To start diagnosis, visually inspect the ignition system with and without the engine running.

■ Connect a scan tool to the diagnostic connector under the dash to find many ignition-related problems.

■ A spark intensity test (spark test) checks the strength of the electric arc (spark) produced by the ignition system.

■ A dead cylinder is an engine combustion chamber that is not igniting and burning its fuel-air mixture on that cylinder’s power stroke.

■ Bad spark plugs can cause a wide range of problems, including misfiring, lack of engine power, poor fuel economy, exhaust odor, rough idle, and hard starting.

■ To read a spark plug, closely inspect and analyze the condition of its tip and insulator.

■ Set the spark plug gap by spacing the side electrode the correct distance from the center electrode.

■ A faulty secondary wire or spark plug wire can have a burned or broken conductor or deteriorated insulation.

■ Proper ignition timing is critical to the performance of an engine. If the ignition timing is off by even 1° of crankshaft rotation, fuel economy and power can drop considerably.

■ A faulty ignition coil may result in a weak spark, an intermittent spark, or no spark at all. The engine may miss or stall. In some cases, the engine will not start at all.

■ A bad ignition switch can cause several problems: the engine may not crank or start, the engine may not shut off when the ignition key is turned off, or the starter may not disengage when the ignition key is returned to run.

■ An ignition control module problem often shows up after a period of engine operation because engine heat soaks into the module and raises its temperature.

■ When a knock sensor “hears” pinging or knocking, it retards ignition timing or lowers turbo boost with the turbo wastegate.