ADT ADT Fuel System & Injection Technology 1 — Questions and Answers
Question 1: Audi's TFSI engine technology combines which two fuel delivery methods to improve efficiency and performance?
- Turbocharging and Gasoline Fuel Stratified Injection (direct injection) (Correct answer)
- Twin turbocharging and port injection only
- Supercharging and carburetion
- Turbocharging and throttle body injection
Correct answer: Turbocharging and Gasoline Fuel Stratified Injection (direct injection)
TFSI stands for Turbocharged Fuel Stratified Injection, combining a turbocharger with gasoline direct injection for precise fuel delivery.
Question 2: On Audi FSI/TFSI engines, the high-pressure fuel pump is driven by:
- A lobe on the camshaft (Correct answer)
- The crankshaft belt directly
- An electric motor
- The power steering pump
Correct answer: A lobe on the camshaft
The high-pressure fuel pump on FSI/TFSI engines is mechanically actuated by a dedicated lobe on the intake or exhaust camshaft.
Question 3: What is the typical high-pressure fuel rail operating pressure range for Audi TFSI direct injection engines?
- 50–200 bar (Correct answer)
- 3–5 bar
- 10–15 bar
- 0.5–1 bar
Correct answer: 50–200 bar
Audi TFSI direct injection systems operate at 50–200 bar of fuel rail pressure, far higher than conventional port injection systems.
Question 4: A customer's Audi A4 2.0 TFSI exhibits rough idle and misfires at cold start. A known common cause on this engine is:
- Carbon buildup on intake valves due to direct injection without port wash (Correct answer)
- Failed MAF sensor only
- Low octane fuel
- Vacuum leak at the brake booster
Correct answer: Carbon buildup on intake valves due to direct injection without port wash
Direct injection engines do not wash the intake valves with fuel, so oil vapor from the PCV system causes carbon deposits, leading to cold-start misfires.
Question 5: When diagnosing a low fuel pressure code on an Audi TFSI, a technician should verify which component FIRST?
- The low-pressure fuel pump (in-tank pump) output pressure (Correct answer)
- The high-pressure injector resistance
- The throttle body position
- The crankshaft position sensor signal
Correct answer: The low-pressure fuel pump (in-tank pump) output pressure
The in-tank low-pressure pump feeds the high-pressure pump; insufficient low-side pressure will prevent the high-pressure pump from meeting rail pressure targets.
Question 6: On Audi EA888 Gen 3 engines, a 'dual injection' system combines direct injection with port fuel injection (PFI). What is the PRIMARY benefit of adding port injectors?
- Port injectors wash intake valves with fuel, preventing carbon buildup (Correct answer)
- They replace the direct injectors at high load
- They reduce turbocharger boost pressure
- They allow the engine to run on diesel fuel
Correct answer: Port injectors wash intake valves with fuel, preventing carbon buildup
Port injectors in the dual injection system spray fuel across the intake valves, preventing the carbon deposits that are common in direct-injection-only engines.
ADT ADT Fuel System & Injection Technology 1
Audi's TFSI engine technology combines which two fuel delivery methods to improve efficiency and performance?