1. The Most Likely Culprits:
* Crankshaft Position Sensor (CKP Sensor): This sensor tells the engine's computer the position of the crankshaft. When hot, these sensors can become unreliable, causing the engine to fail to start. This is a very common cause of hot-start problems.
* Camshaft Position Sensor (CMP Sensor): Similar to the CKP sensor, but monitors the camshaft. A failing CMP sensor can also cause hot-start issues.
* Ignition Coil(s): Heat can cause coils to weaken or fail. If the coil isn't providing sufficient spark when hot, the engine won't start.
* Ignition Control Module (ICM): The ICM controls the ignition system. A failing ICM is another possibility.
2. Less Likely, but Possible Causes:
* Fuel Pump: While less likely to be *only* a hot-start problem, a weak fuel pump might struggle to provide enough fuel when the engine bay is hot.
* Mass Airflow Sensor (MAF Sensor): An inaccurate MAF sensor reading can lead to poor starting, and heat can affect its performance.
* Coolant Temperature Sensor (CTS): A faulty CTS can give the engine computer incorrect information about the engine temperature, leading to poor fuel delivery or ignition timing. This is more likely to cause rough running or stalling than a complete inability to start, but it's worth checking.
* Wiring Issues: Heat can cause wiring to short or develop high resistance, affecting the ignition system or fuel system. Look for any damaged, frayed, or melted wires, especially near the engine.
3. Troubleshooting Steps:
1. Check for Error Codes: Use an OBD-II scanner (or a code reader that works with your car's OBD system, which may be OBD-I in this case – check your owner's manual) to retrieve any diagnostic trouble codes (DTCs). These codes can pinpoint the problem. A 1994 model might not be fully OBD-II compliant, so a scan tool specific to older Chrysler vehicles may be needed.
2. Check the Basics:
* Battery: Ensure the battery is fully charged and the terminals are clean and tight.
* Fuel: Make sure the fuel tank has enough fuel.
* Starter Motor: Check that the starter motor is engaging properly. If you're getting a click, it could be a low battery or a bad starter.
3. Focus on Heat-Related Components:
* CKP and CMP Sensor: These are often the culprits in hot-start issues. You'll likely need a multimeter to test their resistance values; consult a repair manual for your specific model's specifications. Replacing these sensors is often relatively inexpensive and easy.
* Ignition Coil(s): Visually inspect the coils for any signs of damage. Testing requires a multimeter; again, a repair manual will show you how.
* Ignition Control Module (ICM): Testing an ICM can be more complex and often requires specialized equipment.
4. Consider Professional Help: If you're not comfortable working on your car's electrical system, take it to a qualified mechanic. Misdiagnosis and incorrect repairs can be costly.
Important Notes:
* Repair Manuals: A repair manual specific to your 1994 Chrysler Concorde is invaluable for this type of troubleshooting. It will provide wiring diagrams, sensor specifications, and step-by-step procedures.
* Safety: Always disconnect the negative battery terminal before performing any electrical work.
* Heat Soak Test: Let the car sit in the sun for a while to get it really hot. This may exacerbate the problem and help in diagnosing the issue.
By systematically checking these components and using diagnostic tools, you should be able to pinpoint the cause of the hot-start problem in your 1994 Chrysler Concorde. Remember to consult a repair manual for detailed instructions and specifications.
