ASE4 Ignition System Diagnosis and Repair 3

Question 1

A spark plug gap measures 0.065 inches; specification is 0.040 inches. The effect on ignition will be:

Accepted Answer

Higher voltage demand that may cause misfires

Answer

Easier spark firing and better combustion

Answer

Lower voltage demand and improved efficiency

Answer

No effect on performance

Question 2

During an ignition coil primary voltage test with a lab scope, the technician sees no voltage drop across the coil. This indicates:

Accepted Answer

The coil driver transistor or ECM output is not switching

Answer

The coil is functioning normally

Answer

The coil secondary winding is open

Answer

The spark plug gap is too wide

Question 3

A technician observes crossfire between two adjacent ignition wires. The MOST likely cause is:

Accepted Answer

Wires routed too closely together or damaged insulation

Answer

Over-advanced ignition timing

Answer

A faulty crankshaft position sensor

Answer

A weak ignition coil

Question 4

What does a long spark line on an ignition oscilloscope pattern indicate?

Accepted Answer

High resistance in the secondary circuit

Answer

The spark plug gap is too small

Answer

A shorted coil secondary

Answer

Normal coil output

Question 5

An intermittent misfire code P0301 is stored but no misfire occurs at idle. The BEST next step is:

Accepted Answer

Road-test the vehicle under the conditions that set the code

Answer

Replace the spark plug and coil on cylinder #1 immediately

Answer

Perform a compression test on cylinder #1

Answer

Inspect the fuel injector on cylinder #1

Question 6

A technician checks available voltage at the ignition coil positive terminal during cranking and finds only 6 volts. Specification is battery voltage. The MOST likely cause is:

Accepted Answer

High resistance in the power supply circuit to the coil

Answer

A defective ignition coil

Answer

A faulty crankshaft position sensor

Answer

A shorted coil primary winding