AUDI AUDI Engine Management & Fuel Systems 2 — Questions and Answers
Question 1: Which component on an Audi 2.0 TFSI engine drives the high-pressure fuel pump?
- Crankshaft pulley
- A dedicated lobe on the intake camshaft (Correct answer)
- Electric motor
- Exhaust camshaft lobe
Correct answer: A dedicated lobe on the intake camshaft
The HPFP on the 2.0 TFSI is driven by a three-lobe cam on the intake camshaft, which reciprocates the pump plunger to generate high injection pressure.
Question 2: What is the purpose of the Audi exhaust gas recirculation (EGR) system?
- Increase exhaust back-pressure for turbo spool
- Reduce NOx emissions by diluting the intake charge with inert exhaust gas (Correct answer)
- Cool the catalytic converter
- Improve fuel vaporization
Correct answer: Reduce NOx emissions by diluting the intake charge with inert exhaust gas
EGR lowers peak combustion temperatures by introducing exhaust gas into the intake, which reduces the formation of nitrogen oxides (NOx).
Question 3: On an Audi with a turbocharged engine, what is the function of the diverter valve (DV)?
- Recirculates compressed air back to the turbo inlet when the throttle closes to prevent compressor surge (Correct answer)
- Opens the wastegate under full boost
- Controls boost pressure via the ECM directly
- Diverts exhaust flow away from the turbine
Correct answer: Recirculates compressed air back to the turbo inlet when the throttle closes to prevent compressor surge
The diverter valve (also called blow-off or bypass valve) vents compressed air back to the turbo inlet when the throttle closes suddenly, protecting the turbocharger from surge.
Question 4: When an Audi oxygen sensor reads a fixed voltage of approximately 0.45V and does not switch, what does this typically indicate?
- The sensor is reading correctly at stoichiometric air/fuel ratio
- The sensor is lazy or failed and not responding to exhaust gas changes (Correct answer)
- Boost pressure is too high
- The catalytic converter is functioning perfectly
Correct answer: The sensor is lazy or failed and not responding to exhaust gas changes
A healthy narrowband O2 sensor should oscillate between approximately 0.1V and 0.9V; a fixed mid-range voltage indicates a lazy or dead sensor that is no longer reacting to exhaust gas.
Question 5: What Audi fuel system component regulates low-side fuel pressure supplied to the high-pressure pump?
- Fuel pressure regulator on the high-pressure rail
- In-tank low-pressure fuel pump module (Correct answer)
- Fuel vapor purge solenoid
- Fuel cap check valve
Correct answer: In-tank low-pressure fuel pump module
The in-tank low-pressure fuel pump delivers fuel to the HPFP at a regulated low-side pressure, ensuring the high-pressure pump has adequate supply under all conditions.
Question 6: What condition causes the Audi ECM to enter 'limp mode' and restrict engine output?
- Windshield wiper failure
- Detection of critical faults such as boost over-pressure, knock, or sensor failure to protect the engine (Correct answer)
- Low washer fluid level
- Cabin air filter restriction
Correct answer: Detection of critical faults such as boost over-pressure, knock, or sensor failure to protect the engine
Limp mode reduces power output and limits RPM when the ECM detects faults that could cause serious engine damage, such as knock events, over-boost, or loss of critical sensor signals.
AUDI AUDI Engine Management & Fuel Systems 2
Which component on an Audi 2.0 TFSI engine drives the high-pressure fuel pump?