Car Tuning Engine Performance Principles 5

Question 1

What is the role of the mass airflow (MAF) sensor in a modern engine management system?

Accepted Answer

It measures the mass of air entering the engine so the ECU can calculate the correct fuel delivery

Answer

The MAF sensor measures actual air mass entering the engine, giving the ECU the primary data needed to calculate injector pulse width for the correct air-fuel ratio.

Question 2

What is 'short-tube' versus 'long-tube' header design, and how does it affect power delivery?

Accepted Answer

Long-tube headers increase low-RPM torque; short-tube headers favor high-RPM power

Answer

Long-tube headers create better scavenging at lower RPMs for more torque, while shorty headers are more compact and have less dramatic but broader power delivery.

Question 3

In engine tuning, what does 'fuel trim' refer to?

Accepted Answer

The ECU's short-term and long-term adjustments to fuel delivery based on oxygen sensor feedback

Answer

Fuel trim is the ECU's continuous correction to the base fuel map, using O2 sensor data to add or subtract fuel and maintain the target air-fuel ratio.

Question 4

What is 'ring end gap' and why is it critical in a performance engine build?

Accepted Answer

The clearance between piston rings that allows for thermal expansion without seizing

Answer

Ring end gap is the measured space in the ring when installed in the bore, sized to allow thermal expansion without the ends butting together and causing catastrophic ring failure.

Question 5

What is the function of an engine 'knock sensor'?

Accepted Answer

It detects the vibration signature of detonation so the ECU can retard ignition timing

Answer

The knock sensor detects the specific high-frequency vibration of detonation, triggering the ECU to retard ignition timing to protect the engine.

Car Tuning Practice Test

Car Tuning Practice Test

Car Tuning Engine Performance Principles 5