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

Manifold Absolute Pressure (MAP) sensor only

Answer

Throttle Position Sensor (TPS)

Answer

Crankshaft Position Sensor (CKP)

Question 2

What is 'compressor surge' in a turbocharger context?

Accepted Answer

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

Answer

Excessive heat buildup in the turbo housing

Answer

Oil flooding of the compressor wheel bearings

Answer

Overboosting caused by a stuck wastegate

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

Cool the turbine housing with engine oil

Answer

Provide hydraulic pressure to control the wastegate

Answer

Supply oil to the intercooler coolant pump

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

Start the engine immediately and let it idle to circulate oil

Answer

Fill the turbo oil feed line with grease prior to installation

Answer

Bleed the cooling system only — oil feed is self-priming

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

P0087 — Fuel Rail Pressure Too Low

Answer

P0171 — System Too Lean Bank 1

Answer

P0401 — EGR Flow Insufficient

Question 6

What does blue-gray smoke from the exhaust during deceleration typically indicate on an Audi TT with a turbocharger?

Accepted Answer

Oil being drawn past worn turbo shaft seals into the intake

Answer

Rich fuel mixture from a faulty MAF sensor

Answer

Coolant entering the combustion chamber

Answer

Incomplete combustion due to a fouled catalytic converter

Question 7

What is the recommended cooldown practice after hard driving of an Audi TT to protect the turbocharger?

Accepted Answer

Idle the engine for 1–2 minutes to allow oil flow to cool the turbo

Answer

Shut off the engine immediately to reduce heat soak

Answer

Rev the engine to 3,000 RPM for 30 seconds before shutdown

Answer

Switch off the ignition at idle, then immediately restart