Possible turbocharger malfunctions (Mercedes-Benz Sprinter 903)

If the car's engine does not develop full power or cannot reach maximum speed, it can be assumed that there is a fault in the turbocharger, but only if the injection system is known to be in good condition. On the one hand, the cause of the malfunction may be a leak in the turbocharging system, on the other hand, the turbocharger itself may have failed. The search for possible faults should be carried out in the following order.

Leakage in the supercharging system:

check the air pipe between the turbocharger and the intake manifold, passing through the intermediate cooler, for leaks, cracks and breaks, and eliminate possible malfunctions;
check the tightness of the connection between the intake manifold and the cylinder head. Malfunctions here can be caused by a leaky gasket or, in the worst case, a damaged manifold;
leaks can also occur at the joints between the exhaust manifold flange and the cylinder head or between the exhaust manifold and the turbocharger.

Faulty turbocharger:

check the boost pressure at a service station. It may be high or, conversely, low. If the pressure is too high, the boost pressure limiting magnetic valve or fuel pressure regulating valve may be faulty. Diagnostics of the controller's memory device at the service center should show the source of the malfunction;
if the pressure is too low, the diaphragm mechanism of the boost pressure limiting valve may be faulty. Otherwise, the turbocharger is faulty.