Electrical System:
* Crankshaft Position Sensor (CKP): This sensor tells the engine's computer where the crankshaft is in its rotation. A failing CKP sensor can cause the engine to stall intermittently, especially when the engine is hot or under load. It's a common culprit for no-code issues.
* Cam Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor prevents the engine from receiving proper timing information.
* Ignition Coil(s): A weak or failing ignition coil may not consistently provide the spark needed to ignite the fuel/air mixture. This can cause intermittent stalling. Testing each coil individually is necessary.
* Wiring Harness: Damaged, corroded, or loose wiring in the ignition system can interrupt the flow of electricity, leading to stalling. Carefully inspect all wiring related to the ignition system and sensors.
* Battery/Alternator: Although you mentioned good fuel pressure, a weak battery or alternator can cause voltage drops, leading to the engine cutting out. Test the battery and alternator.
* ECU (Engine Control Unit): While less common, a failing ECU can cause intermittent problems without setting codes. This is a more difficult issue to diagnose and usually requires professional help.
Other Potential Issues:
* Vacuum Leaks: A significant vacuum leak in the intake manifold or vacuum lines can disrupt the air/fuel mixture, causing stalling. Inspect all vacuum lines and connections for cracks or leaks.
* Throttle Position Sensor (TPS): A faulty TPS can provide inaccurate information to the ECU, leading to erratic engine behavior.
* Mass Airflow Sensor (MAF): A dirty or malfunctioning MAF sensor can cause inaccurate fuel metering, resulting in stalling. Try cleaning the MAF sensor first (following manufacturer instructions carefully).
* Fuel Pump Relay: While you've checked fuel pressure, a faulty relay might intermittently cut power to the fuel pump, even with a good pump.
* Grounds: Poor electrical grounds can cause unpredictable electrical issues, including intermittent stalling. Check all major engine grounds for corrosion or loose connections.
Troubleshooting Steps:
1. Visual Inspection: Thoroughly inspect all wiring, vacuum lines, and connections for damage or corrosion.
2. Sensor Testing: Use a multimeter or a scan tool capable of live data to test the CKP, CMP, TPS, and MAF sensors. Compare readings to specifications in your repair manual.
3. Check Engine Data: Even without stored codes, a scan tool capable of live data can show you what the sensors are reading while the problem occurs. This will help pinpoint the faulty component.
4. Professional Diagnosis: If you are unable to find the problem yourself, a qualified mechanic with a scan tool and diagnostic expertise can help.
It's crucial to systematically check these components. Start with the easier and more likely candidates (like visual inspection and sensor checks) before moving on to more complex issues. Remember safety first; disconnect the battery's negative terminal before working on electrical components.
