Gas Injector Service

Gas Injector Ultrasonic Cleaning and Testing

Gas Injector Test, Clean and Retest

Oregon Fuel Injection has been flow bench testing, cleaning and resealing gas injectors since the early 1990s. Recently, we replaced our original ASNU gas injector test bench with the latest ASNU Classic GDI test bench. The newest test bench enables us to service GDI (Gasoline Direct Injection) injectors as well as the older port style. Injectors from automotive, motorcycle, ATV, marine, including outboards, E-tec, and GDI injectors are tested, cleaned and resealed.

What does servicing gasoline injectors involve?

  • Gas injectors are externally cleaned and inspected
Gas injectors as received
  • The injectors are tested on the ASNU test bench, and the following results are noted
Injectors installed in the test adapter
  • We inspect for leaks at the pintle nozzle seat and body, with the injector under pressure
  • Spray patterns are observed and noted during the dynamic flow test and the auto flow test.
  • Verify the injector passes the auto rate flow test, which replicates fuel delivery at multiple rpm and pulse rate. Injectors are pulsed from 250 rpm to 10,000 rpm before flow testing. The injectors are pulsed with the correct hold currents and firing in sequential mode, simulating operation at all rpm in the engine.
Spray pattern before cleaning, notice the spray pattern is not the same
  • Dynamic and static flow rates are recorded.
Notice the difference in fuel output between the injectors
  • Ohm resistance is checked electronically during testing and noted
  • Notes are made for anything unusual about the injector during testing
  • The injectors are then cleaned in an ultrasonic cleaner, while pulsing, in order to completely clean all the internal components of the injector
Ultrasonic cleaning gas injectors
  • We then completely re-test the injectors noting leaks (if any), spray pattern, flow test – both dynamic and static and ohm readings.
  • Any injector that fails during the leak test, spray pattern, flow test or ohm test should be replaced.
  • After the final testing, injectors are fitted with new filter baskets, o-rings and pintle caps as available
Spray pattern after cleaning, results in more uniform spray pattern compared to before cleaning
Gas Injector flow test results after cleaning
Injectors cleaned, flow bench tested, new filter baskets and resealed, ready to reinstall.

Cleaning and testing gas injectors out of the engine is the best way to service them.

  • Ultrasonic cleaning is the best way to completely clean the injectors. On vehicle cleaning methods can not use as rigorous of cleaning, without damage to the filter baskets, oxygen sensors or emissions equipment. Cleaning the injectors outside the engine will always deliver a better result. The results of cleaning provide measurable delivery results, with visual spray pattern improvements
  • Spray patterns are visually inspected for proper atomization and spray angle. Injectors in a set are compared side by side. Atomization and spray pattern can not be checked on the engine.
  • Dynamic flow rates are measured in cm2 and can be compared between injectors in a set, verifying a balanced fuel delivery for the set.
  • If flow rates or spray patterns are incorrect, the engine management system will try to compensate fuel deliveries to obtain an average. This means some cylinders will run rich and some too lean. Fuel trim adjustments do not correct the problems, they only compensate for delivery problems, in an attempt to reduce driveability issues.

Our gas injector cleaning and testing methods result in over 95% of injectors returned to OE service levels. Most injector problems are caused by deposits, restricted filter baskets, poor spray patterns and reduced flow. Normal servicing resolves these issues. However, if an injector is stuck closed from contaminated fuel, we would recommend that it be replaced. If the injector is leaking at the body, it would need to be replaced.

GDI injectors on the vehicle normally operate between 75 – 200 bar. On the ASNU test bench, they are tested at 10 bar due to safety reasons. Testing at a lower pressure makes examining the pintle movement easier than testing at a higher pressure, as that can mask free movement.



What is the cost of cleaning and testing 8 gas gm injectors?
Also have 8 others to help creature the best 8 type scenario.


Test, clean, test and reseal usually costs $30-$35 each. It would make sense to service the 1st set of 8 and then decide if 2 or 3 more need to be serviced, unless you wanted a second set. They usually flow within about 2% spread.


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