1. Timing may be retarded . 2. Camshaft or other gears in the valve train incorrectly positioned. 3. Excessive turbo pressure. 4 Engine load excessive. 5. Fuel adulterated with gasoline or other substance. 6. Injector nozzles defective. 7. Engine thermostat may need to be replaced with one that opens at 10+ degrees cooler. 8. Excessive … Read more