This can be caused by several issues, ranging from relatively minor to more serious:
* Spark Plug: A fouled, damaged, or worn-out spark plug in cylinder 4 is the most common culprit. It may be misfiring intermittently or not firing at all.
* Ignition Coil: If your engine uses individual ignition coils (one per cylinder), the coil for cylinder 4 might be faulty. This component provides the high voltage needed to ignite the spark plug. If it's failing, it won't provide enough voltage for consistent ignition.
* Worn or Damaged Spark Plug Wire: While less common in modern vehicles, if your Park Avenue uses individual spark plug wires (rather than coil-on-plug ignition), the wire leading to cylinder 4 could be damaged, frayed, or corroded, causing a poor connection or no spark.
* Fuel Injector: A clogged or malfunctioning fuel injector in cylinder 4 prevents the proper amount of fuel from reaching the combustion chamber, leading to a misfire.
* Valve Problems: A burnt, stuck, or damaged intake or exhaust valve in cylinder 4 will prevent the cylinder from operating correctly. This is a more serious issue.
* Compression Issues: Low compression in cylinder 4 indicates a problem with the piston rings, cylinder walls, or head gasket. This is also a more serious and potentially expensive repair.
* Vacuum Leak: A significant vacuum leak could affect the air-fuel mixture delivered to the cylinder and contribute to a misfire.
What you should do:
Don't ignore the check engine light. Continuing to drive with a misfire can cause further damage to your catalytic converter (a very expensive part to replace).
1. Get it Diagnosed Professionally: While some of the above issues you *might* be able to check yourself (spark plug inspection is relatively straightforward), a mechanic has the tools and expertise to properly diagnose the root cause. They can perform a compression test, check fuel injector operation, and assess the ignition system components far more effectively than you can at home.
2. Don't just replace parts randomly: Throwing parts at the problem without a proper diagnosis is wasteful and may not solve the issue.
A mechanic will be able to pinpoint the exact cause of the misfire in cylinder 4 and repair it efficiently and cost-effectively.
