Owner's Problem Description
The owner has a 2002 Saturn SL2, which they recently changed the engine on. After the replacement, the vehicle cranks and starts for about one second before dying. They can repeat this cycle indefinitely. The owner checked for spark at the coil and confirmed it’s strong. After adding fuel directly into the intake, it runs fine until the fuel runs out. They replaced the fuel filter but saw no improvement and noted good fuel pressure when testing the fuel rail. They also swapped the PCM with no success.
Professional Technical Analysis
The vehicle is a 2002 Saturn SL2, equipped with a 1.9L I4 engine and a manual transmission, likely having around 150,000 miles. The primary symptom is that the engine cranks and starts momentarily but dies immediately. Checking the spark shows good output, indicating that the ignition system is operational. Adding fuel directly allows the engine to run briefly, suggesting the fuel delivery system may not be functioning properly. The fuel filter was changed, but the owner suspects a fuel injection issue as pulse testing showed no activity. Given the details, a possible fuel pressure issue, injector malfunction, or security system interference (indicated by the blinking security light) could be at play. The swap of the PCM from a different model year may require a relearn process. Current conditions show that the vehicle is not starting reliably, posing potential safety concerns if attempted to drive. The intermittent issues suggest a need for further diagnostics focusing on the fuel injection system and security system checks.
Possible Causes
Most common causes (ordered by frequency):
- Fuel Injection System Failure: The injectors are not pulsing, which prevents proper fuel delivery to the engine. This can be due to a faulty injector driver within the PCM or wiring issues leading to the injectors. The injectors should receive a pulsing signal from the PCM, typically ranging from 1-5 milliseconds per pulse. Testing should include checking the resistance of the injectors (typically around 12-16 ohms) and confirming the signal using a noid light. - No injector pulse detected when testing with a noid light. Possible stored codes related to injector control.
- PCM Security Features Activation: The flashing security light indicates a potential security system issue that may be preventing the engine from running. If the PCM does not recognize the key or if there’s an issue with the new steering column and associated chip, the engine may not stay running. The relearn procedure should be performed after replacing the PCM to ensure proper operation. - Security light flashing during cranking, indicating possible theft deterrent system activation. Need to verify key and column compatibility.
- Fuel Pressure Check: While the owner believes there is good fuel pressure, a more thorough test using a fuel pressure gauge should be performed to confirm that it meets the specification of 40-50 PSI. If the pressure drops significantly during cranking, it suggests a fuel pump issue or a blockage in the fuel line. - Owner reports good spray from the fuel rail but lacks proper testing data to confirm pressure specifications.
Diagnostic Steps
Professional Diagnosis Process
Follow these systematic steps to accurately diagnose the issue. Each step builds on the previous one to ensure accurate diagnosis.
- STEP 1 - OBD-II Scan: Begin with a full OBD-II scan using the GeekOBD APP or a professional scanner to retrieve any stored trouble codes. This will help identify if there are any issues related to the fuel injectors or security system. Pay close attention to any DTCs that may indicate injector circuit faults or immobilizer issues.
- STEP 2 - Inspect Fuel Pressure: Connect a fuel pressure gauge to the fuel rail test port. Check that the fuel pressure maintains between 40-50 PSI while cranking. A drop in pressure may indicate a failing fuel pump or blockage. Document the readings for comparison against specifications.
- STEP 3 - Injector Signal Testing: Use a noid light to check for injector pulse signals while cranking. If no pulse is detected, check the wiring and connectors leading to the injectors, and verify the injector resistance to ensure they are functional.
- STEP 4 - Security System Verification: Investigate the security system by attempting to relearn the key. Follow the relearn procedure as specified in the factory service manual. Ensure that the key and ignition components are compatible to avoid immobilizer activation.
