When misfires occur, performance suffers, along with fuel economy, emissions and idle quality.
So, for your engine to fire its cylinder properly, it relies on, three main components.
Consequently, it needs fuel to burn, oxygen to facilitate the burn reaction, and a spark to get things going.
If any of those elements are not present, at the perfect time, the cylinder won’t combust, leading to misfire. And, it won’t start the chain reaction, that leads to a well-running engine.
So, what causes a misfire? Basically, it’s one of three things:
- Loss of spark.
- The air/fuel mixture, is out of balance.
- Loss of compression.
Loss Of Spark
- Worn fouled or damaged spark plugs.
- Bad plug wires.
- A weak coil.
The air/fuel mixture, is out of balance.
“Lean misfires” can occur when the air/fuel mixture, is too lean to burn. Usually, caused by, a dirty, clogged or inoperative fuel injector. Also, air leaks or low fuel pressure, because of a weak fuel pump. In addition, a restricted filter or leaky pressure regulator.
But, low fuel pressure would affect all cylinders, rather than an individual cylinder. A leaky (EGR) valve, can also have the same effect as an air leak, causing a misfire.
Loss of compression
Finally, with loss of compression, the most likely causes are, a leaky exhaust valve or a blown head gasket. So, if two adjacent cylinders are misfiring, it’s likely the head gasket. Also, if an engine is overheating or losing coolant, it’s also likely the head gasket is the culprit.
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