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In recent months I have come along problems with fuel injectors and they seemed to be one of the most overlooked and under-serviced components in the engine, yet their role is so vital.

What are Fuel Injectors?

Fuel injectors spray a fine, atomized fuel in or to the combustion chamber of the engine. This fine spray of fuel combusts when the spark plug is fired in a smooth flame propagation or front which burns the fuel, causing a incredible amount of controlled pressure forcing the piston down the cylinder to the crankshaft.

The diesel injector works in the same principal, except there is no spark plug. The fuel is injected when the piston is arriving to the top of its stroke, the internal heat caused by the compression (or compressed air) ignites the diesel fuel forcing the piston down. It’s a matter of interest because the combustion process is a process of heat accumulation there is a significant KNOCK in a diesel engine; hence this is why diesel engine are more noisy than petrol engines.

What are the Benefits of Fuel Injectors?

Fuel injectors are electronically controlled by computers. It was discovered that unburnt fuel was one of the greatest pollutants so Governments put stipulations on car manufacturers to get emissions down. Fuel injection was the answer. Engineers discovered that using computer hardware and now software can program fuel injectors to inject fuel in a 1000th/second – so divide a second into a thousand and take 6-8 thousands of that to keep the injector spraying fuel (include injector dead time in that equation). This is called milliseconds or injector ON TIME. This can also be represented in injector duty cycle – on time compared the time the injector is not energized in a given cycle.

The real benefits was better fuel economy, more power, less emissions, easier start up, easier transition from cold start to normal operating stage.

Problems & Symptoms of Poor Performance Injector

  • Performance loss;
  • Engine stutter, hesitation and stumbling;
  • Engine misfire;
  • Increase in fuel consumption;
  • Rough idling, engine stalling;
  • Failed emission tests. (Do not mention the VW debacle – that’s another story!) 

The Fix or Solution

Bring your car to MANNY`S MECHANICAL REPAIRS. Part of our service is to inform our customers that fuel injectors should be serviced every 80 000-100 000km and here is the reason:

  • Injectors collect contaminants from the fuel tank or from a bad batch of fuel from the refineries.
  • Injectors can develop carbon build up on the spraying pintles causing a partial blockage. 
  • Injectors can have electromagnetic faults affecting the speed and operation of their performance. 
  • Injectors may have fuel pump delivery problems. 

Here at MANNY`S MECHANICAL REPAIRS we have full diagnostic facilities. We also recommend and perform inline fuel rail injector service, which cleans intake manifold, pistons, injectors and exhaust. we add fuel tank additive at 80 000 to 100 000km.

At 180 000-200 000km we strongly recommend the physical removal of injectors, to be bench tested before ultrasonic bathed and have each individual injector flow & load tested with results recorded, new o rings ,seals fitted.


On one last note, we strongly recommend replacing fuel filters on every diesel service.. true the cost is higher but we are constantly astounded of the ridiculous amounts of water and rubbish found in diesel fuel filters.

I hope this has helped.

– Manny, 0411 496 621
To serve, to perform, to guide.


At Manny’s Mechanical Repairs you are in good hands, our main services include, Safety CertificatesLogbook ServiceFree Pickup & Delivery, and Car Cooling System Repairs.

We have the latest diagnostic equipment and my work van is fitted out with an industrial air compressor. This enables me to perform heavy duty work and give you – the customer – the best service at any place and at any time.

For Bookings and enquiries, please contact us on 0411 496 621email us at or visit our site