ADT Engine Performance & Tuning 2

Question 1

On a 2019 Audi A4 2.0T, the ECU reports a lean condition at high load but fuel trims are normal at idle. Which component should you inspect first?

Accepted Answer

High-pressure fuel pump (HPFP)

Answer

The HPFP on TFSI engines commonly fails to maintain adequate rail pressure under high load, causing lean conditions that don't appear at idle.

Question 2

Audi's Valvelift System (AVS) switches between two cam profiles. Which symptom most commonly indicates a failed AVS solenoid?

Accepted Answer

Rough idle and misfires at low RPM

Answer

A failed AVS solenoid prevents switching from the low-lift profile, causing rough idle and low-RPM misfires because the engine stays on the low-lift cam lobe.

Question 3

When performing a cylinder contribution test on an Audi 3.0T supercharged engine using ODIS, which parameter indicates a weak cylinder?

Accepted Answer

RPM drop greater than 20 RPM when that cylinder is disabled

Answer

During a cylinder contribution test, a healthy cylinder causes a significant RPM drop when disabled; less than 20 RPM drop indicates the cylinder is not contributing normally.

Question 4

A 2020 Audi SQ5 with the 3.0 TFSI exhibits a whistling noise that increases with engine load. The boost pressure reading is normal. What is the most likely cause?

Accepted Answer

Cracked supercharger bypass valve housing

Answer

A cracked supercharger bypass valve housing allows pressurized air to whistle through the crack under load while not significantly affecting overall boost readings.

Question 5

Audi's homogeneous-split injection mode combines port and direct injection. What is the primary purpose of this dual-injection strategy?

Accepted Answer

To reduce intake valve carbon deposits while maintaining combustion efficiency

Answer

Port injection washes the intake valves with fuel, preventing the carbon buildup inherent to direct injection only, while direct injection maintains efficiency.

(ADT) Audi Diagnostic Technician Practice Test

(ADT) Audi Diagnostic Technician Practice Test

ADT Engine Performance & Tuning 2