Boost pressure check

A necessary condition for the efficient operation of the turbocharger and the achievement of the required boost pressure is the complete tightness of the connections both on the side of the intake pipeline and on the side of the exhaust manifold. Boost pressure is checked at full engine load on the go or on a bench with running drums. Checking at each pressure measurement should be carried out within 10 s, for which disconnect the vacuum hose from the inlet pipeline going to the fuel supply corrector for the boost pressure of the high-pressure fuel pump. Connect the pressure gauge hose to the intake manifold and vacuum hose through the tee. Move the pressure gauge to the passenger compartment, while it can be placed on the right front seat or on the instrument panel near the windshield, making sure that the pressure gauge hose is not pinched when the hood is closed.

Open the stop valve of the pressure gauge by pushing towards the pressure gauge. Measure boost pressure at full engine load:

• on the stand: in third gear at a crankshaft speed of 4000 rpm:
• when the car is moving: in 2nd gear, at the same time braking the car to maintain a speed of about 60 km / h.

An increased boost pressure indicates a malfunction of the boost pressure control valve. In this case, the turbocharger must be replaced. With reduced boost pressure, disconnect the pressure reducing valve hose from the air intake hose, close the hose opening with a suitable 25 mm plug and secure the plug with a hose clamp. Repeat boost pressure test. If the boost pressure is correct, replace the relief valve. If boost pressure remains low, replace turbocharger.