ADT Engine Performance & Tuning 3

Question 1

An Audi RS3 with the 2.5 TFSI five-cylinder shows misfires on cylinders 1 and 5 only under boost. Compression and leak-down tests are normal. What should you suspect?

Accepted Answer

End cylinders receiving unequal boost pressure due to manifold design

Answer

On 5-cylinder inline engines, the end cylinders (1 and 5) are farthest from the center charge air feed and can experience lower boost pressure distribution under high load.

Question 2

Audi specifies a 'running-in' oil service for new engine replacements. Which engine parameter should be verified before clearing the service reminder after a running-in oil change?

Accepted Answer

Confirm no metal particles appear in the drained oil beyond acceptable limits

Answer

During engine break-in, fine metal particles are expected; the running-in oil change removes these particles before they cause premature wear.

Question 3

When diagnosing Audi's active noise cancellation (ANC) system, a customer complains of a droning noise in the cabin at 2000 RPM. How does ANC generate its counter-noise?

Accepted Answer

Microphones sample engine noise and the audio system emits phase-inverted sound through cabin speakers

Answer

ANC uses interior microphones to detect unwanted noise and plays an inverted waveform through the vehicle's speakers to cancel the sound via destructive interference.

Question 4

A 2018 Audi Q7 3.0T displays fault P0087 (fuel rail pressure too low). The low-pressure fuel pump reads 5.5 bar. What is the most likely root cause?

Accepted Answer

Failed high-pressure fuel pump not building rail pressure from the 5.5 bar supply

Answer

On GDI engines, the low-pressure side reads normal while P0087 points to the high-pressure pump failing to multiply pressure to the 150-200 bar range required by the direct injectors.

Question 5

Audi's lambda control uses pre-cat and post-cat oxygen sensors. If the post-cat sensor mirrors the pre-cat sensor waveform closely, what does this indicate?

Accepted Answer

The catalytic converter has low efficiency and is not storing oxygen

Answer

A healthy catalyst stores and releases oxygen, causing the post-cat sensor to show a slow, lazy signal; a mirroring waveform means the catalyst is not storing oxygen and has low efficiency.

(ADT) Audi Diagnostic Technician Practice Test

(ADT) Audi Diagnostic Technician Practice Test

ADT Engine Performance & Tuning 3