Systems Repair Worksheet Chapter 28 Pages 836-873 Name

Ignition Diagnosis & Service 62 Points Due Date

1. A is incomplete combustion of the A/F mixture. Not always caused by the ignition system

2. Complete combustion is when all of the & in the emulsion have been burned.

3. (violent burning) occurs when part of the A/F begins to burn on its own.

A collision of the two flame fronts in the combustion chamber will result in a spark knock or ping.

4. also results in a ping or spark knock, but occurs when the A/F mixture

begins to burn before the spark occurs. Any hot spot in the combustion chamber can cause this.

5. ignition problems are those that affect all cylinders.

problems affect more than one, but less than all cylinders.(common = primary & series-wired components)

6. An uneven running engine (w/frequency) is an indication of a problem.

7. No-start, ignition related problems are likely to be common problems in the circuit.

8. Ignition systems can be the cause of: 1) starting or no starting, 2) idle,

3) engine , 4) , stumble, or poor acceleration, 5) ,

6) bucking, 7) (pinging), 8) fire & fire.

9. Dirty grounds & connections can cause resulting in modules that burn out or

sensors that indicate improper parameters of operation. Moisture can cause shorts to ground.

10. Critical placement of ignition wiring is important to minimize the effects of EMI. T F

11. Some ignition control modules use a coating of silicone grease

between the unit and its mounting to help conduct heat away and prevent heat-related failure.

12. Distributor caps & rotors as well as DI & EI coil towers, should be inspected for and

carbon tracks that indicate that high-voltage electricity has found a low-resistance path for flow.

13. Visual inspection, spark tests, volt & ohm tests are all used to troubleshoot no-start. T F

14. Oscilloscopes and exhaust gas analyzers are commonly used to diagnose misfires. T F

15. Scopes give over graphic representations of ignition system function.

16. The line indicates the voltage required to overcome resistance to initiate a spark.

17. The line indicates the kV needed to sustain the spark and also the spark duration.

18. The oscillations in the intermediate section show kV’s dissipating after spark has occurred.

19. The section shows the length of time primary current flows trying to saturate the coil.

20. The 3 basic scope patterns are:

21. The firing line is affected by anything that adds to the secondary circuit, as well

as non-electrical conditions like engine temperature, air/fuel mixture and compression pressures.

22. The voltage required to fire the plugs with the engine under increased load.

23. Maximum output is checked with a spark tester installed that will check for 35 kV.

24. At idle, firing kV should be between . Spark duration should be about mSec.

25. voltage in the ignition coil is shown by coil oscillations in the intermediate section.

26. testing ignition components includes subjecting them to cold, heat, and moisture.

27. Before using a , like the MODIS, to check ignition systems be familiar with scale, filter,

threshold, peak detect, time scale or sweep, voltage scale or sensitivity, trigger, & slope settings.

28. Improperly set can affect engine vacuum, emissions, performance, and spark knock.

29. If base timing is incorrect, all other timing settings by the PCM will be wrong too. T F

30. Centrifugal, vacuum, & EST advance units can be checked with an advance light.

31. Name 5 ignition system parts that can be checked with an ohmmeter: (hint: switches & coils)

______Ingition SwitchBOOAPP / ______Pick-up CoilEGRCATAIR Pump / ______CKP & CMPVSSECTIAT / ______Ignition CoilTransformer / ______Plug WiresVacuum AdvanceCentrifugal AdvanceEST

32. probes have 3 lights: red = >10 volts green = <3 volts yellow flashes with voltage change

33. sensors can be checked using a hammer & either a scope or a scanner to monitor change.

34. Cold fouling or “wet out” of the spark plugs is caused by an overly A/F mixture or misfire.

35. An ohms check of plug wires cannot detect a short to ground that causes a misfire! T F

36. Two long plug wires, especially those close to each other in the firing order & the engine, should

not be placed side by side for a long span because 1-8-4-3-6-5-7-2 1-3-7-2-6-5-4-8

1-8-7-2-6-5-4-3 1-5-4-2-6-3-7-8

a condition called , which is unwanted induction of a rogue spark can occur.

37. A procedure called timing must be done after distributor R & R before the engine

can be started.

Crank the engine in order to bring # cylinder to on the compression stroke.

Align the marks on the harmonic balancer or flywheel to the timing specification.

Set the distributor in with the facing the # spark plug wire connection on the cap.

Mesh the drive pin with the oil and the distributor gear with the gear.

Crank the engine around again to that everything is properly aligned.

Tighten the distributor hold-down and install the #1 spark plug & the secondary wiring.

Start the engine and check the dynamic (running timing) with a .