Engine is misfiring. 2.5L 2003 nissan altima 130k miles. pulled spark plugs and one plug gap is smashed flat. what could cause this

HERE'S THE LINK FOR THE 2.5 ENGINE,HERE/S THE 3.5 ENGINE.

check the battery in the key and the engine immobiliser for operation

suggest try replacing the plugs with the old once.quite posssible faulty plug.

remove plugs and check. make sure that the plug gap is not closed causing misfire. we have some issues with power valve screws coming loose and getting inside of the cylinder closing the gap on plugs. some power valve plates come loose also and get into the intake. if you find plug gap closed, chances are that screw came loose and got inside of the cylinder. thats when you need to removed upper plenum and check all plates and screws to see if they are still there. ofcourse, there is a special tool to line up the plates if the screws are missing or loose and need to be replaced.

The spark plug gaps should be around 1.0 to 1.2 mm Max. If they have worn to become that wide or they have done more than 12,000 miles or 20,000 Km, it would be better to replace them rather than trying to clean and regap. If you want more information on spark plugs such as recommend type for your engine and failure indications, you can visit the websites of the major plug manufacturers such as KLG, Champion, Bosck and NGK.

If you get ck engine light on , you have a cyl. number
that misfires , ck vacuum leaks on intake manifold around that area aspecially intake manifold gasket.

Try fuel injectors.

possible causes are: faulty spark plug, coil not firing or arcing, injector fouled. start with your spark plugs and if replacement is neccessary, replace with ngk or nd spark plugs.

The correct spark plug gap is .044