Checking uniform operation of turbochargers

Air mass flowing through left and right cylinder banks is registered separately by left and right mass air flow sensor and can be observed at the same time in measured value block 002.

Air mass allows a conclusion to be drawn concerning function of turbochargers. If there is a very large difference between air mass of left and right cylinder bank at approx. 2600 rpm, turbocharger of cylinder bank with lower air mass value displayed may be defective.

• Vehicle diagnostic, testing and information system VAS 5051 connected; vehicle self-diagnosis and vehicle system "01 - Engine electronics" selected and engine idling.

Display on VAS 5051:

Fig 1: Display On VAS 5051 - Checking Uniform Operation Of Turbochargers

Courtesy of AUDI OF AMERICA, INC.

1 - Enter display group

• Using keypad -2-, enter "002" to select Display group 002 and confirm entry with Q button.
• Take vehicle for a test drive.
• Change to Tiptronic gear "4" at approx. 50 km/h.
• Accelerate vehicle at full throttle (do not operate kick-down), and have a second mechanic watch rev counter.
• When engine speed reaches 2600 rpm, second mechanic presses "PRINT" key on VAS 5051.
• Compare displays in display zones 3 and 4.
Fig 2: Display Group 002: Intake Air Mass
Courtesy of AUDI OF AMERICA, INC.
• Press the < button to exit from function "08 - Read data block".

If specification is not attained:

• Detect cause of malfunctions according to fault table. See FAULTS IN CHARGE PRESSURE CONTROL FUNCTION .
• Install air filter housing. See INSTALLING .