What is Engine Misfires?

Engine misfire occurs when the engine do not fire at the right time or do not fire at all. This is one of the signs that your automotive have troubles. The spark plug is set electrically to fire at right time ensuring that the engine has enough amount of power present. This can happen because of different varying reasons including vacuum leaks, poor wiring, bad fuel delivery or carbon and oil fouled spark plugs. In all cases no matter how the trouble is, getting it fixed is the right way to prevent even further engine complications. Below we are going to look at causes, symptoms and prevention measure of engine misfire.

Causes of Engine Misfire

Worn out Spark Plugs

Spark plugs get worn out with time due to spark plug fires that burns a few metal molecules of plug electrodes during ignition. After a long period of time you find that the electrodes become worn out and their sharp edges are completely eroded. The erosion gradually increases the gap of electrodes, which raises the voltage of power that is required to generate a spark. It gets to the point that the ignition cannot produce the required voltage making the plug to misfire.

Vacuum Leaks

A vacuum leak in the cylinder of the engine in question can cause lack of enough fuel. This leaks commonly occur at vacuum horse connection and at intake port gaskets causing partial loss of compression leading to misfiring.

Weak or Leaking Fuel Injector

Another cause of misfiring is a weak fuel injector a condition that is referred to as “lean misfire” and occurs because there is no enough fuel in the combustion chamber. This condition only affects one cylinder including a shorted or open injector, dirty cylinder and fuel injector poor wiring. This compression challenges causes a misfire that includes leaky head gasket, exhaust valve or bent intake.

Worn out Rings or Valve Seals

Spark plugs which have oil ash is a clear indicator that oil is leaking due to worn out piston rings or stem seals. This if happens to your car engine might consequently cause misfiring.

Symptoms of Engine Misfire

Carbon Deposits

One of the indicators of a problematic spark plug is carbon deposits on the plugs. These deposits are dry and sooty which indicates that the ignition of the car is weak. It causes the engine not to start or hesitates and misfires. The recommendation is to check for sticky choke, clogged air cleaner, worn ignition points and high float level.

Ash Deposits

Another symptom that your car might develop this condition is light brown deposits on the sides or at the center of the electrodes. They are gathered from oil additives or fuel additives and their excessive accumulation at the electrode might cover the spark leading to hesitation and misfiring.

Oil Deposits

Oil deposit is another symptom that indicates that your plugs need attention. In this one you will notice oil coating which is usually caused by poor oil control. Oil might have leaked to the combustion chamber and past worn valve guide possibly the piston rings causing engine hard starts, hesitation and misfiring.

Over Heated

Overheating of plugs is another indicator of engine misfire. It makes the white insulators to get blisters, electrodes becomes worn out leading to disappearance of deposits, which shortens the plugs lifespan as a result. It is recommended that you ensure that the radiator is not clogged and coolant is at the correct levels.


The last symptom that should indicate your engine might start misfiring is cracked or chipped insulators. This is usually caused by improper gap setting techniques of pistons leading to their damage if they are not fixed timely. It is important to take precaution while setting the gaps of new plugs to avoid engine lugging.

Prevention of Engine Misfire

Finally, to prevent engine misfire you should ensure that spark plugs are set right, if they are not, the engine will not be able operate well with enough power. As mentioned earlier a misfire occurs when the engine does not function well. The bottom line could be the spark plugs are blown, bad wiring or some the causes mentioned above. This problem can only be avoided and prevented by proper maintenance your engine car according to the vehicle’s instruction manual. Ensure that your car is regularly checked by a qualified mechanic to assess its condition.