* Crankshaft Position Sensor (CKP): This is a very common cause of hot-start problems in Discovery 2s (and many other vehicles). When hot, the sensor can malfunction, preventing the engine from receiving the signal needed to fire. The sensor itself can degrade with heat, or the wiring/connections can become compromised.
* Camshaft Position Sensor (CMP): Similar to the CKP sensor, a faulty CMP sensor can cause starting issues, especially when hot. It's less common than the CKP, but still a possibility.
* Ignition Coil(s) or Ignition Module: Heat can cause these components to weaken or fail. When hot, they may not provide the necessary spark to ignite the fuel-air mixture.
* Fuel Pump Relay or Fuel Pump: Although less likely given the engine cranks, a heat-soaked fuel pump might struggle to deliver sufficient fuel when hot. A failing fuel pump relay could also exhibit similar symptoms. Listen carefully to see if you hear the fuel pump prime when you turn the key to the "on" position before attempting to crank.
* Mass Airflow Sensor (MAF): While less probable for a purely hot start issue, a malfunctioning MAF sensor might provide inaccurate readings when the engine is hot, leading to poor starting.
* Wiring/Connections: Heat can damage wiring harnesses and connections, particularly those related to the ignition system. Check for any signs of melting, corrosion, or loose connections, especially in the engine bay.
Troubleshooting Steps:
1. Check for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for any stored trouble codes. This is the first and most important step. Even if the issue isn't consistently throwing a code, there might be a stored code related to the underlying problem.
2. Check the CKP and CMP Sensors: Visually inspect them for damage. A more thorough check would involve testing their output signals with a multimeter (requires some technical knowledge).
3. Inspect Wiring and Connections: Carefully examine all wiring related to the ignition system, fuel system, and sensors for signs of damage or loose connections. Pay particular attention to areas that get very hot during operation.
4. Check the Fuel System: Listen for the fuel pump's priming sound when you turn the ignition key. If you don't hear it, investigate the fuel pump relay and the pump itself.
5. Consider the Starter Again (Though Less Likely): Although you've replaced it, a very rare possibility remains that the new starter is faulty or has a heat-related problem (though less likely than the other components listed above).
Important Note: Working on the ignition system involves high voltage. If you're not comfortable working with automotive electrical systems, it's best to take the vehicle to a qualified mechanic. Improper handling can result in injury or further damage to your vehicle.
