You should have C.O.P. ( coil on plug) there are no wires.
Remove the spark plug wires from your 2002 Mercury Grand Marquis spark plugs. Remove the spark plugs by turning them to the left with a deep well 5/8 socket. Reverse the process to install the new spark plugs.
I would replace the spark plugs after 50K, the wires and plugs again at 100K.
That's most likely a bad spark plug. It's best to replace all along with the wires too. About a $300 job at a good repair shop.
On the 2001 Mercury Grand Marquis , it has the Coil On Plug ( C.O.P. ) ignition system with ( 8 ) individual coils on the 4.6 liter SOHC , V8 engine ( it's not the same , as say , a 1997 Mercury Grand Marquis that had ( 2 ) coil packs with four towers on each coil pack and spark plug wires with the Electronic Distributorless Ignition System ( EDIS )
Not really much to do. Spark plugs, air filter, oil and filter, fuel filter, and check that the ign. wires are good.
Replace spark plugs and wires Replace fuel and air filters Replace PCV valve
On a 1996 Mercury Grand Marquis with the 4.6 liter SOHC , V8 engine : There are ( 2 ) coil packs with ( 4 towers on each ) They are located at the front area of the engine , just follow the spark plug wires to each of the ( 2 ) coil packs
Start with the ign. wires and the spark plugs.
It could be a number of reasons - bad spark plugs, plug wires - plugs gapped incorrectly, plugged catalatyc convertor, te list goes on and on . . . .
To replace spark plug wires on a 3300 Oldsmobile engine, open the hood and remove the wires from the end of the engine. The number of spark plug wires most often corresponds to the number of cylinders your engine has.
On a 1995 Mercury Grand Marquis with the 4.6 liter SOHC , V8 engine : It has the Electronic Distributorless Ignition System ( EDIS ) that has ( 2 ) coil packs ( each with 4 towers ) located near the front of the engine ( just follow the spark plug wires )
Disconnect the battery, remove the spark plugs wires and boots and remove the spark plugs. Put in the spark plugs, replace the spark plug wires and boots, and connect the battery.