* Dirty Air Filter: A clogged air filter restricts airflow to the engine, reducing power.
* Spark Plugs/Ignition System Issues: Worn, fouled, or damaged spark plugs prevent efficient combustion, leading to power loss. Similarly, problems with ignition coils or wires can have the same effect.
* Fuel System Problems: A clogged fuel filter, low fuel pressure, or problems with fuel injectors can restrict fuel delivery, reducing power. Bad gas can also be a culprit.
* Mass Airflow Sensor (MAF) Issues: A faulty MAF sensor provides inaccurate readings to the engine's computer, leading to poor fuel/air mixture and reduced power.
* Throttle Body Issues: A dirty or malfunctioning throttle body can restrict airflow.
* Exhaust System Restrictions: A clogged catalytic converter or muffler can restrict exhaust flow, impacting engine performance.
* Transmission Problems: Issues with the transmission, such as low fluid or worn components, can lead to sluggish acceleration and reduced power.
* Engine Problems: More serious issues like worn engine components (pistons, rings, valves), low compression, or internal leaks can significantly reduce horsepower.
* Sensor Issues: Various other sensors (oxygen sensor, etc.) can malfunction and affect the engine's performance.
To diagnose the specific cause of horsepower loss in a Lincoln Navigator, a mechanic would need to perform a thorough inspection and diagnostic testing.
