Vibe L4-1.8L VIN L (2003)
Fuel Injector: Testing and Inspection
Fuel Injector Circuit Diagnosis
CIRCUIT DESCRIPTION
The sequential multiport fuel injection (SFI) system is controlled by the powertrain control module (PCM). The PCM energizes the solenoid coil of
each fuel injector individually by completing the electrical circuit to ground. When energized the fuel injector solenoid operates the solenoid plunger,
allowing pressurized fuel to be injected into the intake port of the cylinder. The fuel pump will pressurize the fuel rail and the fuel injectors as long as
the engine is cranking and the PCM is receiving the ignition system reference pulses.
DIAGNOSTIC AIDS
Check for any of the following conditions:
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Water, contaminated fuel, or inferior quality fuel can cause a no start or hard start condition even though the fuel injectors and circuitry are OK.
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Check for a faulty spray pattern from the fuel injector nozzle if both the fuel injector solenoid and the fuel injector circuit are OK.
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There may be fuel spray at the fuel injectors and the indicated fuel pressure may be correct, yet there may not be enough fuel to start the engine. If
the fuel injectors and the injectors' circuit are OK, and fuel spray is detected, some fuel injector nozzles may be partly blocked or restricted. If the
PCM receives incorrect inputs from the various information sensors the fuel delivered by the fuel injectors may be inadequate to start the engine.
Check all engine data parameters with a scan tool and compare the values indicated with expected values or values on a known good vehicle.
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The normal fuel injector resistance is 13.4-14.4 ohms at 20°C (68°F).
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If you were sent here by a DTC P0300 and all the injectors checked OK, the Misfire Current Cylinder or Misfire Graphic information on a scan
tool can be used to determine which injector circuit should be examined in detail.
An intermittent malfunction may be caused by a fault in the fuel injector electrical circuit. Inspect the wiring harness and the components for an
intermittent condition. Refer to Intermittent Conditions. See: Computers and Control Systems/Testing and Inspection/Initial Inspection and
Diagnostic Overview/Diagnostic Strategies
TEST DESCRIPTION
Step 1
