Exam 27: Ignition System Diagnosis and Service

A defective EI coil may cause cylinder misfiring.

Technician A says large amounts of EMI can collapse the field in a coil and cause a plug to fire. Technician B says poor spark plug cable insulation may cause EMI. Who is correct?

Describe two important precautions that should be taken during all ignition system tests.

All ignition system problems will set a DTC in the vehicle's PCM and can be read with a scan tool.

The height of the ____________________ line in a secondary oscilloscope pattern represents the amount of voltage needed to initiate a spark across the spark plug gap.

An engine may start with a faulty camshaft sensor, but it may only run in the ____________________ mode because the fuel injectors cannot be synchronized without the camshaft signal.

Describe how to test the integrity of a suspect electrical connection.

Insufficient timing advance or retarded timing at higher engine speeds could cause hesitation and poor fuel economy.

What is Mode #6 data?

Mode ____________________ scan tool data displays the test values stored at the time a particular monitor was completed. This data can be useful in engine misfire diagnosis.

Technician A says white or grayish powdery deposits on secondary cables at the point where they cross or near metal parts indicate that the cables' insulation is faulty. Technician B says if the spark plug wire for #2 cylinder is damaged and the other wires look good, replace only the damaged wire. Who is correct?

Describe how to quick-check a knock sensor.

Identify various drivability problems that an ignition system misfire can cause.

What problems typically cause DTCs that indicate a misfire at an individual cylinder (P0301, P0302, P0303, etc.)?

Describe a cylinder performance (balance) test.

Technician A performs a cylinder performance test [power balance test] to determine which cylinder is misfiring. Technician B uses a vacuum gauge to pinpoint the misfiring cylinder. Who is correct?

Ignition coil testing is being discussed. Technician A uses an ohmmeter to measure primary and secondary resistance. Technician B uses an oscilloscope and a test spark plug to measure maximum coil output voltage. Who is correct?

While testing a coil in an EI ignition system, Technician A says an infinite reading means that the winding has zero resistance and is shorted. Technician B says the secondary winding in a waste spark [doubled-ended] coil should be checked by connecting the meter across the two secondary terminals. Who is correct?

What are the causes of detonation?

If the needle on a vacuum gauge drops significantly every two revolutions of the engine, the fault is a ____________________ problem.