AUDI AUDI Engine Management & Fuel Systems 1 — Questions and Answers
Question 1: What is the primary function of the Audi Motronic engine control module (ECM)?
- Controls only the transmission shift points
- Manages fuel injection, ignition timing, and emission controls (Correct answer)
- Operates the ABS hydraulic unit
- Regulates interior climate control
Correct answer: Manages fuel injection, ignition timing, and emission controls
The Motronic ECM integrates fuel injection, ignition timing, idle control, and emissions management into a single engine management system.
Question 2: On an Audi TFSI engine, what does the 'FSI' component of direct injection mean operationally?
- Fuel is injected into the intake manifold
- Fuel is injected directly into the combustion chamber at high pressure (Correct answer)
- Fuel is pre-mixed with air before the throttle body
- Fuel supply is gravity-fed
Correct answer: Fuel is injected directly into the combustion chamber at high pressure
FSI (Fuel Stratified Injection) injects fuel directly into the cylinder at pressures up to 200 bar, improving combustion efficiency and reducing fuel consumption.
Question 3: Which Audi engine sensor measures the mass of air entering the engine to calculate fuel delivery?
- Manifold absolute pressure (MAP) sensor
- Mass airflow (MAF) sensor (Correct answer)
- Throttle position sensor (TPS)
- Coolant temperature sensor (CTS)
Correct answer: Mass airflow (MAF) sensor
The MAF sensor measures the actual mass of air entering the intake and provides the ECM with the primary load signal for fuel injection calculations.
Question 4: What condition does a negative long-term fuel trim (LTFT) value indicate on an Audi?
- The engine is running lean and adding fuel
- The engine is running rich and reducing fuel delivery (Correct answer)
- The oxygen sensor has failed
- The exhaust gas recirculation valve is stuck closed
Correct answer: The engine is running rich and reducing fuel delivery
A negative LTFT means the ECM is subtracting fuel because the engine is running rich, indicating excess fuel or a vacuum-related issue.
Question 5: On Audi TFSI engines, what common issue is caused by carbon buildup on the intake valves?
- Oil pressure drops rapidly
- Rough idle, misfires, and reduced power due to restricted airflow past valves (Correct answer)
- Transmission slipping
- Power steering failure
Correct answer: Rough idle, misfires, and reduced power due to restricted airflow past valves
Because direct injection bypasses the intake valves, oil vapors from the PCV system deposit carbon on valve stems and seats, restricting airflow over time.
Question 6: What does the Audi high-pressure fuel pump (HPFP) pressure sensor monitor during engine operation?
- Return fuel temperature
- Actual rail pressure versus commanded rail pressure (Correct answer)
- Fuel tank level
- Crankcase pressure
Correct answer: Actual rail pressure versus commanded rail pressure
The fuel rail pressure sensor feeds live rail pressure data to the ECM so it can adjust HPFP cam lobe stroke to maintain target injection pressure.
AUDI AUDI Engine Management & Fuel Systems 1
What is the primary function of the Audi Motronic engine control module (ECM)?