The main difference between a diesel engine with unit injectors, and a diesel engine with a conventional fuel injection system is that each atomizer is integrated with its own high-pressure pump. The high pressure pump is mechanically operated by a rocker arm and the solenoid valve is controlled by the engine management system.
The unit injector technology is no longer used in new engines, mainly because it is a relatively expensive technology. Unit injector are harder to fine-tune and emission reductions are harder to manage compared to common rail injectors.
Of course the unit injector technology also has advantages: energy is only used when the pump nozzle is pressed and delivering fuel pressure.
Like all other types, also for unit injectors internal contamination is one of the biggest causes of problems and excessive soot emissions.
The spray pattern is incorrect due to soot deposits. Poor quality or old oil is one of the biggest causes of problems with unit injectors which eventually even may result in a damaged camshaft or other major defects.
Causes of faulty injectors
- Poor quality or old oil
- Poor fuel quality
- Wrong fuel
- Aging (> 150.000km)
- Mechanical or electromagnetic defect
- EGR problems
- Faulty assembly
- Poor sealing of the unit injector in the cylinder head
KCPerformance is the right place for unit injector repairs. We can recondition, upgrade or replace any unit injector. Of course this is done using the correct torque and fitting into the seats of the cylinder head. Consequential damage caused by the initial injector problems can be fixed in one go.