GASOLINE DIRECT INJECTION SYSTEMS

Direct injection improves combustion efficiency, increases fuel economy and lowers emissions

But what does the technician need to know about direct fuel injection fitted to a motor vehicle?
Premier Auto Trade (PAT) explains Gasoline Direct injection (GDI) systems are commonplace in the modern automotive industry.
Just like Electronic Fuel injection (EFI) replaced Carburettors years ago, Direct Injection systems are the new standard says PAT, which states the major advantages of a GDI system is the increased fuel efficiency allowing manufacturers to downsize engines and reduce emission levels. 
Like many systems, even modern direct injection parts fail and before working on GDI systems technicians should be aware of the dangers and changing component technology, says PAT.
It is common for GDI injectors to be triggered by voltages as high as 120V, and technicians should never disconnect injector connectors during operation, warns PAT.
Fuel pressure is another area of caution, as fuel line pressures can be in excess of 200 Bar. Fluid at these pressures can cause serious skin or eye injuries and so procedures outlined by the manufacturer on lowering residual fuel pressure safely should be followed.

GDI Injector information – Bosch HDEV5
The GDI Injector is a multi-hole, electrical magnetic solenoid injector (not Piezo type) that is used on system pressures of up to and exceed 200Bar.
This type of injector may be located at the side or centre of the combustion chamber, depending on the crown design of the piston. An average Injector Pulse Width is approx. 0.4µs and the Injector winding resistance cold would be approximately 1.5 ohms.

Direct Injection Pumps (DIP)
Direct Injection Pumps are generally driven by the camshaft and may utilise Roller, Follower or Bucket type drives that contacts cam lobe.
Some V configured engines can utilise 2 DIP units, one per bank, and contain an electric pressure regulator solenoid that is controlled by the PCM. Most also contain an internal pressure relief valve.
PAT explains that a “clicking” sound may be audible during operation and utilising a suitable scan tool can assist with verifying if the DIP is functioning correctly.
Premier Auto Trade says its commitment to the aftermarket’s supply requirements has driven the expansion of its GDI components offering, with increases in the GDI Injector and Direct Injection Pumps ranges. The Premier Auto Trade Fuel range also continues to grow, now with 20 GDI injectors covering over 480,000 vehicle applications.
The full range of Premier Auto Trade Fuel products are now available in the aftermarket via a network of specialised resellers and leading automotive groups.

For more information, visit www.premierautotrade.com.au