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Home >> Buick >> 2007 >> Allure CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 61 (Engine Control System & Fuel System - 3.8L - Troubleshooting & Diagnosis) >> Fuel Injector Diagnosis (w/J39021 or Tech 2) >> Component Testing >> Pressure Drop Calculation

Pressure Drop Calculation

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
  1. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
  2. Obtain a pressure drop value for each fuel injector.
  3. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
  4. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop.
    • If the difference between any individual pressure drop and the average pressure drop is more than 20 kPa (3 psi), perform the Fuel Injector Balance Test.
    • If the difference between any individual pressure drop and the average pressure drop is still more than 20 kPa (3 psi), replace the fuel injectors.
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