Audi TT Turbocharging and Forced Induction Systems 2

Question 1

Which sensor directly informs the ECU of the amount of air entering the turbo system on the Audi TT TFSI?

Accepted Answer

Mass Air Flow (MAF) sensor

Answer

The MAF sensor measures the actual mass of air entering the engine, which the ECU uses to calculate appropriate fueling and manage boost delivery.

Question 2

What is 'compressor surge' in a turbocharger context?

Accepted Answer

Unstable airflow reversal through the compressor at low flow/high pressure

Answer

Compressor surge occurs when the compressor operates outside its efficient range and airflow reverses direction, causing a distinctive chuffing noise and potential damage.

Question 3

What is the primary function of the turbocharger oil feed line on the Audi TT?

Accepted Answer

Lubricate and cool the turbo center bearing cartridge

Answer

Engine oil is supplied to the turbo's center section to lubricate and cool the high-speed journal bearings or ball bearings that support the shaft.

Question 4

After replacing a turbocharger on an Audi TT, what is the correct procedure before first startup?

Accepted Answer

Disconnect the ignition and crank the engine to pre-lubricate the turbo before firing

Answer

Cranking without ignition pre-lubricates the new turbo's bearings with oil before the unit reaches operating speed, preventing dry-start damage.

Question 5

On the Audi TT, what fault code is typically stored when the ECU detects insufficient boost pressure relative to the requested target?

Accepted Answer

P0299 — Turbocharger Underboost Condition

Answer

P0299 indicates the actual boost pressure is below the ECU's commanded target, pointing to leaks, wastegate issues, or turbo failure.

Audi TT - Certified Audi TT Specialist Practice Test

Audi TT - Certified Audi TT Specialist Practice Test

Audi TT Turbocharging and Forced Induction Systems 2