Spark plug gap

That should be under the hood on the Federal
Emission Label

Any spark plug manufactures web site, has it next to
the plugs avail to fit your engine code

GAP=0.044"
I recommend this plug type for long life and good idle quality.
MOTORCRAFT Part # SP405

Make: MERCURY
Model: GRAND MARQUIS
Year: 1999
Engine: V8 - 4.6L - FI - - GAS

Part Number: RS12YC
GAP : .054" (Original Equipment Manufacturer and/or Original Equipment Equivalent)

Hope this helps.

I got code PO 305 on a 2002 Mercury Grand Marquis, what is the spark plug wire part called
This will have a direct coil over ignition with a coil over each spark plug. The coil is the electrical part over the spark plug. The coil also has a rubber part that is called the boot or spark plug boot. The boots can be purchased separately but the coils will come with new boots.

is it #5 coil,

Have you checked to see if there is any spark coming out of the number 5 coil?



and should I replace the coil and spark plug and what should the spark plug be gapped at?

When was the last time the spark plugs where changed? It may be due for all the spark plugs to be changed. The spark plug gap is usually listed on the emissions sticker under the hood. It should be .050 - .056 or very close to that.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Spark plug gap .054"

The recommended spark plug gap is .054.

for what the spark plugs? if so the gap is .054"

go to or call an auto pARTS STORE they can tell you the plug gap.

1998 Mercury Grand Marquis
4.6 liter V-8 VIN "W"



I will get you the rest of the info in just a few hours...I am at work!

Think it is 0.54 but not positive. It should be listed in the back of your owners manual.