2009 Nissan Altima
my car started shaking very bad I was able to drive it to the nearest part store to be placed on a scanner. Cylinder 1 was misfiring. I replaced all spark plugs and cylinder 1 was filled with oil. Now my car is still doing the same thing but worse.
Your cylinder 1 wasn't filled with oil until you removed the spark plug and all the oil in the spark plug tube drained into the cylinder.
Your cylinder #1 spark plug tube seal in the valve cover is leaking. The oil that accumulated in the spark plug tube has shorted out the ignition coil.
You need to replace the valve cover (and the valve cover gasket) ((buy both from the dealer, don't use aftermarket)) and replace the cylinder #1 ignition coil (you can use a good aftermarket for it).
Be sure to clean all of the oil out of the spark plug tube and to remove the spark plug and replace it while doing the job.
There's plenty of youtubes on doing the Altima valve cover replacement
Do a compression test. I suppose it is high mileage engine.
