Audi Workshop Service and Repair Manuals

Special tools, testers and auxiliary equipment required

• ◆ V.A.G 1390

• ◆ VAS 5051

or

• ◆ V.A.G 1551 with V.A.G 1551/3 A

Test sequence

• ‒ Start final control diagnosis and activate solenoid valve for boost pressure limitation -N75:

=> Diesel direct-injection and glow lamp system (4-cyl.) ä 06.97; Repair group 01; Self diagnosis of diesel direct-injection system; Final control diagnosis

=> Diesel direction-injection and glow lamp system (4-cyl.) 07.97 ä; Repair group 01; Final control diagnosis

• ◆ Solenoid valve for boost pressure limitation -N75 should operate audibly.
• ◆ The boost pressure control linkage of the vacuum unit on the turbo charger should move to and from (at least 3 ... or 4 times while there is a vacuum in the vacuum reservoir).

If linkage does not move because solenoid valve is not working:

• ‒ Check boost pressure limitation solenoid valve -N75 .
• ‒ Check all vacuum hoses are fitted and not leaking => Page 21-4onwards.

If linkage does not move, even though solenoid valve is working:

• ‒ → Connect hand vacuum pump V.A.G 1390 to boost pressure regulating valve and check that linkage moves freely between both end stops.

If the linkage moves, but the boost pressure specified values are not attained:

• ‒ Fit a new turbocharger.

If the linkage does not move freely, or moves in jolts: (irregular performance when driving):

• ‒ Fit a new turbocharger.