Can you test GDI/Piezo injectors on a Port injection machine?

Lets get this out of the way up front:

• Q: How do I know if a shop is using the right machine for GDI/Piezo injectors?
• A: If a shop is using a machine for GDI/Piezo injectors with “graduated cylinders” or beakers as shown below circled in red… it’s the wrong machine.

 

 

 

 

 

 

 

 

Today there are GDI/Piezo specific machines, but they are very expensive and thus creates a barrier to entry. GDI/Piezo Injectors are more akin to diesel injectors than port injectors. In fact, the current generation of GDI/Piezo machines uses the same chassis and interface as the Diesel injector machines do. The cost in setting up an actual GDI/Piezo machine is gasp worthy. The incentive then is to mis-represent the capability of the legacy port Injection machines in an attempt to avoid losing business.

Actual GDI/Piezo specific machines come with manufacturer-specific test plans that are constantly being updated and added to via WIFI connectivity. These test plans can be accessed on a digital front panel using the Injectors Model number to pull up the specific manufacturer injector test suite. Test plans contain multiple tests, each with specific flow corridors and pressures that need to perform within the specified parameters on a unique per test basis.

“Spray Pattern” is not a functional GDI/Piezo test. There are no graduated cylinders it is all electronically analyzed internally to the machine. A port injector machine will spray GDI/Piezo injectors at 90 psi, in practice they atomize at 2000 psi.

Testing a Gasoline Direct Injection (GDI) or Piezoelectric injectors on a machine designed for Port Fuel Injection (PFI) injectors is not recommended due to significant differences in their operating principles and requirements. Here’s why:

Key Differences Between GDI/Piezo and PFI Injectors

1. Operating Pressure:
   1. GDI Injectors: Operate at much higher pressures, typically between 500 psi to 3,000 psi (35–200 bar).
   2. PFI Injectors: Operate at much lower pressures, usually around 40–70 psi (2.7–4.8 bar).
   3. A PFI machine cannot replicate the high pressures required for GDI injectors, making tests inaccurate or impossible.
2. Spray Pattern and Atomization:
   1. GDI/Piezo injectors are designed for precise fuel atomization and spray patterns to match the combustion chamber shape, often requiring specialized testing equipment to evaluate their spray performance accurately.
   2. PFI machines are not equipped to simulate the combustion chamber dynamics or measure spray quality for GDI/Piezo injectors.
3. Control Signals:
   1. GDI/Piezo injectors use more complex electronic signals (e.g., piezoelectric or solenoid-driven actuators) to control fuel delivery with high precision.
   2. PFI injectors typically use simpler solenoid-driven mechanisms, and a PFI tester may not provide the correct signals to operate a GDI/Piezo injector.
4. Test Medium:
   1. GDI/Piezo injectors often require specific testing fluids or setups designed for their higher operating pressure and atomization requirements.
   2. Using incorrect fluids or test setups can damage the GDI injector or yield invalid results.

What Happens if You Use a PFI Machine for GDI/Piezo Injectors?

• Low-Pressure Testing: A PFI machine will not provide the pressure required to properly test the injector’s performance, leading to incorrect flow rates and spray pattern evaluations.
• Incomplete Functionality Testing: Important parameters like leakage, spray atomization, and high-pressure operation cannot be assessed.
• Potential Damage: Testing a GDI/Piezo injector on a PFI machine might damage the injector or the machine if the pressure or control signals are mismatched.

How to Properly Test a GDI/Piezo Injector

1. Use a GDI/Piezo-Specific Injector Tester:
   • These machines are capable of providing the high pressures and control signals required for accurate testing of GDI/Piezo injectors.
   • These machines also test for similar parameters  flow rate, and leakage etc, however it is done using Dynamic Electronic Mass (BK) Measurement and it not eye ball calibration in a graduated cylinder.
   • The Injectors have test multiple different plans outlined by manufacturers that are specific to inject serial numbers.
   • The flow tests measured by graduated cylinders is not a valid test, these injectors atomize at 200+ PSI they do not spray.
   • Spray patters and eye ball calibration of good/bad is also not a valid test, these injectors atomize at 200+ PSI they do not spray.
   • These injectors atomized pulses are measured with mass sensors mass and not total volume sprayed over time.
   • Port Injection machines with grossly insufficient pressures will spray the injectors and not atomize them.
2. Test Fluid: Ensure you’re using a compatible testing fluid recommended for GDI/Piezo systems which is different than Port Injector requirements.
3. Professional Calibration: GDI/Piezo injectors often require calibration data, which should be verified during testing.

Conclusion

A GDI/Piezo injector cannot be properly tested on a PFI machine due to differences in pressure, control, and performance requirements. Always use GDI/Piezo -specific testing equipment for accurate and reliable results. How do you know if they are cleaned if you can’t properly test them on hte wrong machine to determine that?

See our Video where we test a GDI injector on both machines.

Properly Testing GDI/Piezo Injectors