In this part of the world diesel has ~1500 ppm sulfur (against <50 ppm in Europe) and who knows what else... I use an external device to clean my injectors with a 50% cleaner (Wurth LBW400) / 50% diesel solution every 10,000 kms or so, otherwise exhaust gas will start smelling bad & fuel consumption would increase. Fill a canister with the said mix and pressure it up to 4 bar through compressed air and a regulator. Disconnect the hoses at the fuel pressure regulator leaving the fuel pump running in a closed circuit, and feed the engine from outside with the canister. Turn on the engine and let it run until the mixture runs out. Then reconnect everything back and purge the fuel system. Results are immediately noticeable, as in a more responsive & quiet engine as well as improved fuel efficiency.
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Matt