ADT ADT Fuel System & Injection Technology 2

Question 1

A 'fuel trim' value of +25% on a long-term fuel trim (LTFT) reading on an Audi TFSI indicates:

Accepted Answer

The ECM is adding significant fuel, suggesting a lean condition (vacuum leak, low fuel pressure, or faulty MAF)

Answer

+25% LTFT means the ECM is compensating heavily for a lean condition by adding extra fuel, indicating a significant air leak or fuel delivery deficiency.

Question 2

What special tool is required to correctly time the high-pressure fuel pump camshaft lobe on an Audi 2.0 TFSI engine during installation?

Accepted Answer

Camshaft locking/alignment tool set specific to the EA888 engine

Answer

Audi EA888 engines require a specific camshaft locking tool set to correctly position the cam lobe for high-pressure pump installation and prevent engine damage.

Question 3

Which fuel system component on Audi direct injection engines is responsible for regulating high-side rail pressure by controlling the amount of fuel the high-pressure pump displaces per stroke?

Accepted Answer

Fuel Pressure Regulator Valve (N276) on the high-pressure pump

Answer

The N276 solenoid valve on the high-pressure pump modulates fuel displacement per stroke to maintain the target rail pressure commanded by the ECM.

Question 4

A technician suspects a leaking high-pressure fuel injector on an Audi 3.0 TFSI. The BEST method to confirm this without disassembly is:

Accepted Answer

Monitor individual cylinder fuel trim imbalance data with a scan tool and perform a static leak test

Answer

Cylinder-specific fuel trim data reveals imbalances that indicate a leaking injector, and a static leak test confirms internal leakage without disassembly.

Question 5

On Audi vehicles, the fuel tank pressure sensor is used primarily in conjunction with which system?

Accepted Answer

Evaporative Emissions (EVAP) system leak detection

Answer

The fuel tank pressure sensor monitors tank pressure changes to detect EVAP system leaks as part of the onboard leak detection routine.

(ADT) Audi Diagnostic Technician Practice Test

(ADT) Audi Diagnostic Technician Practice Test

ADT ADT Fuel System & Injection Technology 2