as a result of bad spark plugs
No,car will not run rich.Infact it gives misfires since escaping fuel will be the ultimate result if we use wrong spark plugs.
Loose spark plugs would result in a loss of compression. This would make starting difficult and if the engine ran at all it would do so badly.
The main reason a car misfires is because the spark plug wires are not installed correctly. Check the car's firing order to ensure the spark plug wires running from the distributor cap to the spark plugs (in the cylinders) are in the right order. One or more spark plugs could be damaged or worn so the firing order is correct, but the spark plugs are not sparking into the spark plug wires to ignite the engine.
How long spark plugs last depends on the brand of spark plug and the condition of the car. In a well maintained car, some spark plugs will last from 3 to 7 years.
Old spark plugs can make a car misfire, run rough, and not fire at all.
The same way you gap spark plugs for any car that uses spark plugs.
what kind of car?
your engine will start but run badly on a multi cyl. ie. more than one only 1 plug may be down, not often more than 1 together
The engine as delivered in a new car has all spark plugs, but a replacement engine almost never comes with spark plugs as they are considered a "consumable."
Plugged/damaged catalytic converter. Dirty fuel filter. Dirty air filter. Worn spark plugs.
Like any car it depends on how many cylinders the car has. If it is a 4 cylinder then it has 4 spark plugs. If it's a 6 cylinder it has 6 spark plugs. An 8 cylinder truck has 8 spark plugs