Car Tuning ECU Remapping and Calibration 2

Question 1

What does the term 'closed-loop' operation mean in ECU fuel control?

Accepted Answer

The ECU uses oxygen sensor feedback to continuously correct fuel delivery

Answer

Closed-loop operation means the ECU reads O2 sensor data and trims fuel trims in real time to maintain target lambda.

Question 2

Which parameter is most critical to calibrate when increasing boost pressure on a turbocharged engine?

Accepted Answer

Fuel injector pulse width and ignition timing

Answer

Higher boost increases cylinder pressure and heat, so fueling must be enriched and ignition timing retarded to prevent knock.

Question 3

What is 'knock retard' and why does the ECU apply it?

Accepted Answer

Automatic ignition timing reduction when detonation is detected

Answer

The ECU retards ignition timing when knock sensors detect detonation, protecting pistons and bearings from damaging pressure spikes.

Question 4

What does VE (Volumetric Efficiency) represent in an engine tune?

Accepted Answer

The ratio of actual airflow into the cylinder to theoretical maximum airflow

Answer

VE is the ratio of actual air mass drawn into a cylinder versus what it could theoretically hold at atmospheric pressure.

Question 5

When a tuner uses a wideband lambda sensor instead of a narrowband sensor, what key advantage does it provide?

Accepted Answer

It can measure AFR across a wide range rather than only near stoichiometry

Answer

Wideband sensors accurately measure lambda from very rich (~0.65) to very lean (~1.6), enabling precise tuning across all operating conditions.

Car Tuning Practice Test