start with new plugs
To fix a misfire on cylinder 1 in a 1997 Subaru Legacy with a 2.5L engine, start by checking the spark plug and ignition coil for wear or damage, as these are common causes of misfires. Replace any faulty components, and ensure the spark plug gap is correct. Next, inspect the fuel injector for cylinder 1 to ensure it is functioning properly and delivering fuel. Finally, check for vacuum leaks or compression issues in the cylinder, as these can also contribute to misfires.
Cross-threaded spark plug.
Could be a bad coil (each cylinder has its own) common problem
P1399 is a pending code for random or multiple cylinder misfires.
i tmakes the car judder a i and the engine misfires
Your 1996 Pontiac Grand Prix will experience cylinder misfires when one or several of the spark plug wires are bad. A bad spark plug can also cause the problem.
Could be a dead fuel injector.
Chek out the ignition coils, the wires and the spark plugs..
2001 ford f 150 misfire on acceleration
possible misfires caused by spark plug/coil wires
You have to find out what is causing random misfires in the engine. See related question below.
Plugs, wires, coil, distributor, injector, internal engine....