* Ignition System Issues (despite replacements): While you replaced the coil, plugs, and wires, there could still be underlying ignition problems:
* Coil overheating: Even a new coil can fail when hot. It might be a faulty coil or a wiring issue causing excess heat buildup.
* Distributor cap and rotor (if applicable): These components can crack or suffer carbon tracking that worsens with heat, leading to misfires when warm. Inspect these carefully; they may not have been replaced.
* Ignition module: This is often overlooked and can fail when hot.
* Wiring harness issues: Heat can cause wiring to short or create high resistance, particularly in older vehicles. Look for chafing or damaged insulation near the engine.
* Fuel System Issues (despite filter and injector service):
* Fuel pump: A failing fuel pump might deliver less pressure when hot, leading to fuel starvation. Check fuel pressure when the engine is hot.
* Fuel pressure regulator: This regulates fuel pressure; a faulty one could allow excessive pressure when cold and insufficient pressure when hot.
* Vapor lock: Though less common with fuel injection, if the fuel lines run close to hot components, vapor lock could occur when the engine is hot, preventing proper fuel delivery.
* Cooling System Issues:
* Overheating: The engine overheating (even slightly) can cause many of the problems listed above. Check your coolant level, hoses, thermostat and radiator for leaks or damage.
* Sensor Problems:
* Temperature sensor: An inaccurate coolant temperature sensor could cause the computer to adjust fuel delivery improperly when the engine is warm. This is a highly suspect area given the cold/warm behavior.
* Mass airflow sensor (MAF) or throttle position sensor (TPS): These sensors regulate fuel mixture and could malfunction when hot.
Troubleshooting Steps:
1. Check for overheating: Ensure your cooling system is functioning correctly. A simple temperature gauge check is a must.
2. Check fuel pressure hot and cold: This is crucial. You need a fuel pressure gauge to see if pressure drops significantly when the engine is warm.
3. Inspect distributor cap and rotor (if applicable): Even if you didn't replace them, a visual inspection is important.
4. Test the ignition coil when hot: This may require letting the engine run until warm, then testing the coil's output. Safety first – work with a professional if you aren't comfortable.
5. Check for error codes (if equipped): A diagnostic code reader can give clues to the problem.
6. Inspect wiring harness: Look for any damage, particularly around the engine where heat is highest.
Without more specific details (like what exactly was done during the injector service), pinpointing the exact cause is difficult. But the cold-start/warm-death pattern strongly suggests a heat-related problem within the ignition or fuel delivery systems, potentially exacerbated by a sensor issue or overheating engine. A mechanic with experience in older vehicles will likely be the fastest and most effective way to diagnose and solve this.
