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Central Sequential Port Injector Balance Test (CSI)

NOTE: Central Sequential Port Injector Balance Test has been revised due to Technical Service Bulletin (TSB) 61-63-16, dated February, 1997. See SMU - SECTION 6E - REVISED INJECTOR BALANCE TEST .

The injector balance test is used to pulse the injector for a precise amount of time, spraying a measured amount of fuel in the intake manifold. As each injector is pulsed, a drop in fuel rail pressure occurs. This pressure drop can be recorded and compared to other injectors. All injector should have the same pressure drop of 1.5 psi (.11 kg/cm2 ).

CAUTION: To avoid possible vehicle fire, wrap a shop towel around fitting to avoid fuel spillage.
NOTE: Allow engine to cool to avoid irregular readings due to "hot soak" fuel boiling. To prevent flooding, INJECTOR BALANCE TEST should not be repeated more than once without starting and running engine.
  1. Perform on-board diagnostics. Check for Diagnostic Trouble Code (DTC). If DTC(s) are present, diagnose DTC first. If DTC(s) are not present, go to next step.
  2. Turn ignition off. Connect Fuel Pressure Gauge (J-39021-301) to pressure tap. Unplug injector harness connector. Connect Injector Switch Box (J-39021-210). Turn ignition on. Monitor fuel gauge. Fuel pressure should be 60-66 psi (4.2-4.6 kg/cm2 ). If pressure is as specified, go to step 3). If pressure is not as specified, check fuel pump and fuel lines for restriction.
  3. Run fuel pump for at least 2 seconds after ignition is turned on. Energize injectors one at a time. Note fuel pressure for each injector. Fuel pressure should drop about 1.5 psi (.11 kg/cm2 ) on each injector. If fuel pressure drop is as specified, go to next step. If fuel pressure drop is not as specified, perform injector coil test. See INJECTOR COIL TEST (CSI).
  4. Remove upper manifold assembly. Connect Poppet Nozzle Tester (J-34730-230). Connect a fused jumper wire (10-amp) to fuel pump test connector. Energize each injector one at a time, fuel should spray from each poppet nozzle tester. If fuel did not spray from an injector, go to next step.
  5. Replace faulty injector and poppet nozzle assembly. After replacing injector and poppet nozzle assembly, go to next step.
  6. Install Tech 1 scan tool. Select DTC, CLEAR INFO. Start engine. If engine starts and continues to run, go to next step. If engine does not start or starts and dies, repeat step 2).
  7. Warm engine to normal operating temperature. Select DTC, FAILED THIS IGN. If additional DTC(s) are displayed, diagnose DTC. If DTC(s) are not present, go to next step.
  8. Using scan tool, select CAPTURE INFO, REVIEW INFO. If additional DTC(s) are present, diagnose DTC. If DTC(s) are not present at this time, system is okay.
CAUTION: To avoid possible vehicle fire, wrap a shop towel around fitting to avoid fuel spillage.
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