1. Diagnose the underlying cause: Dieseling isn't a problem in itself; it's a *symptom* of a problem. Before trying fixes, figure out *why* your engine is overheating. Common culprits include:
* Lean Fuel Mixture: The most frequent cause. A lean mixture burns hotter, increasing the chance of dieseling. This can result from:
* Faulty fuel injectors: Clogged or malfunctioning injectors can deliver insufficient fuel.
* Vacuum leaks: Air leaking into the intake system leads to a lean mixture.
* Faulty Mass Airflow Sensor (MAF) or Manifold Absolute Pressure (MAP) sensor: These sensors regulate the fuel-air mixture. Incorrect readings lead to improper fueling.
* Dirty air filter: Restricts airflow, leading to a lean condition.
* Ignition System Issues: Although less common, problems here can contribute:
* Weak spark: Incomplete combustion can leave hot residues in the cylinder.
* Pre-ignition: The fuel ignites before the spark plug fires, raising combustion chamber temperatures.
* Carbon Buildup: Excessive carbon deposits in the combustion chamber insulate the cylinder walls, increasing heat retention.
* Low-quality fuel: Fuel with a low octane rating or containing contaminants can lead to increased combustion temperatures.
* Overheating Engine: If your engine is already running too hot (low coolant, failing thermostat, radiator issues), dieseling is more likely.
2. Solutions based on the cause:
* Check and replace the air filter: A simple, inexpensive first step.
* Inspect for vacuum leaks: Carefully examine all vacuum hoses and connections for cracks or loose fittings. A smoking propane torch near suspect areas (while the engine is off) can help reveal leaks; be extremely careful!
* Have the fuel injectors tested and cleaned or replaced: This is often the most effective solution for lean mixtures.
* Inspect and replace the MAF or MAP sensor if necessary: These sensors are crucial for proper fuel mixture. A diagnostic scan can reveal if they are malfunctioning.
* Check for carbon buildup: This often requires professional decarbonization, either through walnut shell blasting or chemical cleaning.
* Address any cooling system problems: Ensure the cooling system is properly functioning (coolant level, thermostat, radiator, water pump).
* Use higher-octane fuel: This can help to prevent pre-ignition and reduce combustion temperatures. However, it's generally not a long-term solution.
* Have a diagnostic scan performed: A professional mechanic can use a scan tool to check for trouble codes and identify potential problems in your engine's control system.
3. Immediate Action (Temporary Fix):
If you're experiencing dieseling frequently, turning the ignition key to the "accessory" position (not "on" or "start") immediately after turning the engine off can sometimes interrupt the run-on. This reduces the voltage to the fuel system. This is not a *solution*, but a temporary workaround to prevent damage until the underlying problem is identified and repaired.
Important Note: Dieseling can cause serious engine damage if left unaddressed. It's best to consult a qualified mechanic specializing in Corvettes or high-performance vehicles to diagnose and repair the problem promptly. Improperly diagnosing and addressing this issue could lead to more significant and costly repairs.
