Table of contents: Leak in the turbocharging system ↓ Faulty turbocharger ↓
If the turbocharger is not working properly, this can be determined by a loss of power or failure to reach top speed, assuming the fuel injection system is working properly. This could be caused by a leak in the system or a faulty turbocharger. The following sequence of checks is recommended.
Leak in the turbocharging system
Check the air hose between the turbocharger and the fuel line (collector) through the charge air cooler for fractures, cracks, loose connections, etc. and, if found, eliminate them.
Check for leaks between the cylinder head and the intake manifold. This can be caused by faulty gaskets or, in some cases, a misaligned manifold.
Leaks may be in the connecting flanges between the exhaust manifold and the cylinder head or between the exhaust manifold and the turbocharger.
Faulty turbocharger
Have the boost pressure checked at a workshop. It may be too high or too low.
If the pressure is too high, the reason may be a malfunction of the boost pressure limiting solenoid valve or a malfunction of the boost pressure control valve pressure chamber. Reading the memory of the diagnostic device in the workshop will help to determine where the malfunction is.
If the pressure is too low, then the boost pressure limiting device's plenum chamber can be suspected. Otherwise, the turbocharger must be faulty.