ASE Advanced Engine Performance Specialist 3

Question 1

A knock sensor that fails or is disconnected will typically cause the ECM to:

Accepted Answer

Retard timing to a conservative default

Answer

Without valid knock feedback, the ECM retards timing for protection, often reducing power and economy.

Question 2

On a returnless fuel system, fuel pressure is controlled primarily by:

Accepted Answer

The PCM varying pump duty cycle via a driver module

Answer

Returnless systems commonly use a PCM/fuel pump control module to vary pump speed and maintain target pressure.

Question 3

A misfire that occurs only under load and high RPM, with secondary ignition showing high firing voltage, points to:

Accepted Answer

Worn spark plugs or a weak coil under demand

Answer

High required firing voltage under load indicates excessive gap or weak spark from worn plugs/coils.

Question 4

When a scan tool shows the O2 sensor stuck at a high voltage (~0.9V), the condition usually indicates:

Accepted Answer

A rich exhaust or biased sensor

Answer

High O2 voltage corresponds to a rich mixture, though a contaminated/biased sensor can also read high.

Question 5

A volumetric efficiency (VE) calculation is a useful advanced diagnostic to detect:

Accepted Answer

Restricted intake/exhaust or cam timing problems

Answer

Calculated VE compared to expected reveals breathing problems like restrictions or incorrect cam timing.

ASE Practice Test