ASE4 Ignition System Diagnosis and Repair

Question 1

A technician finds a spark plug with a black, sooty deposit. This condition indicates:

Accepted Answer

A rich fuel mixture or oil fouling

Answer

A lean fuel mixture

Answer

Over-advanced ignition timing

Answer

Normal combustion deposits

Question 2

An ignition coil primary resistance measures 0.5 ohms. The specification is 0.4–0.8 ohms. This means the coil is:

Accepted Answer

Within specification and serviceable

Answer

Open and must be replaced

Answer

Shorted and must be replaced

Answer

Weak and should be replaced as a precaution

Question 3

A spark plug wire shows 10,000 ohms of resistance per foot. This is considered:

Accepted Answer

Too high — the wire should be replaced

Answer

Normal for a carbon-core suppression wire

Answer

Too low — excessive current will damage the coil

Answer

Acceptable only for distributor-type systems

Question 4

An engine misfires only under heavy load. Spark plugs and wires test good. The NEXT most likely cause is:

Accepted Answer

Weak ignition coil output under high demand

Answer

A faulty crankshaft position sensor

Answer

A leaking injector

Answer

A faulty MAP sensor

Question 5

What is the purpose of the secondary ignition system's high voltage?

Accepted Answer

To ionize the spark plug gap and initiate combustion

Answer

To power the ECM

Answer

To charge the battery during engine braking

Answer

To operate the fuel injectors

Question 6

When diagnosing a no-start condition, the technician confirms no spark at any cylinder. The FIRST component to check is:

Accepted Answer

The crankshaft position sensor

Answer

Individual ignition coils

Answer

The spark plugs

Answer

The ignition switch