ASE4 Computerized Engine Controls

Question 1

A MAP (Manifold Absolute Pressure) sensor reads 4.8 volts at idle. Normal is approximately 1.0–1.5 volts. The engine runs rich. This indicates the MAP sensor is:

Accepted Answer

Reading too high (high pressure), causing the ECM to add excess fuel

Answer

Reading too low, causing the ECM to add fuel

Answer

Within normal range for altitude compensation

Answer

Causing a lean condition

Question 2

An IAT (Intake Air Temperature) sensor reads -40°F in ambient temperature of 70°F. The engine cranks hard and runs rich when cold. This indicates the IAT sensor is:

Accepted Answer

Open circuit, defaulting to a maximum cold reading

Answer

Shorted to ground, reading hot air temperature

Answer

Correct — the sensor reads ambient temperature as cold

Answer

Reporting a lean condition signal

Question 3

Which sensor is MOST responsible for closed-loop fuel control correction?

Accepted Answer

Upstream oxygen (O2) sensor

Answer

MAP sensor

Answer

MAF sensor

Answer

IAT sensor

Question 4

A TPS (Throttle Position Sensor) reads 0.3 volts at closed throttle and 4.8 volts at WOT. These values indicate:

Accepted Answer

Normal operation within typical range

Answer

The sensor is faulty and must be replaced

Answer

The sensor is providing a biased signal

Answer

The ECM will default to open-loop control

Question 5

A CTS (Coolant Temperature Sensor) stuck at a high-temperature reading will cause the ECM to:

Accepted Answer

Lean out the mixture as if the engine is fully warm

Answer

Enrich the fuel mixture as if the engine is cold

Answer

Activate cold-start enrichment strategies

Answer

Disable the EGR system

Question 6

The ECM enters open-loop operation when:

Accepted Answer

The coolant temperature is below the closed-loop enable threshold

Answer

The O2 sensor is sending accurate voltage signals

Answer

Both fuel trims are at 0%

Answer

The catalytic converter is at operating temperature