
Engine misfire requires replacement of cylinder liners, pistons, etc. Causes of cylinder scoring: Severe piston misalignment, cylinder liner roundness and cylindricity tolerances exceeding allowable ranges, greatly reducing the sealing between pistons and cylinder liners. High-temperature gases in the cylinder leak downwards, destroying the oil film between pistons and cylinder walls, leading to cylinder scoring and poor break-in. Engine misfire: Engine misfire refers to insufficient power caused by engine failure, resulting in lack of power where a minority of cylinders in the total number are not functioning. Engine misfire shortens the lubrication oil usage cycle, easily causes sudden stalling, increases fuel consumption, produces black smoke, and results in power loss.

Last time I experienced severe engine misfire and shaking. During the repair, all four ignition coils and a set of spark plugs were replaced. The mechanic said these are the most prone to failure. If the fuel injectors get clogged, they need cleaning or replacement. For older cars, it's also necessary to check if the ignition wires have aged. In severe cases, the engine might need disassembly to replace valve seals, piston rings, and even the cylinder head gasket. As a reminder, after repairs, the ECU data needs to be matched, otherwise it might trigger fault codes. Regular maintenance is crucial - don't wait until it shakes like a tractor before getting it fixed.

Dealing with a misfire requires a step-by-step approach. First, read the fault codes to identify which cylinder is affected. In most cases, simply replacing the ignition coil or spark plug will suffice. However, if the fuel injector is clogged, it needs cleaning or replacement. If a cylinder pressure test shows insufficient pressure, it's likely the piston rings or valves need replacing. For corroded wiring connectors, replace the entire wiring harness—this is especially important for older vehicles. Remember, all seals must be renewed to prevent oil leaks. Always opt for genuine OEM parts, as aftermarket parts won't last.

From my experience, it's best to prioritize replacing the spark plugs—they're cheap and yield quick results. The ignition coils have a high failure rate, so it's advisable to replace all four. If the fuel injectors are clogged, soaking them in a specialized cleaning solution might salvage them. In case of internal engine damage, a major overhaul is necessary: replacing piston rings, valve springs, and the entire cylinder head gasket set. A reminder not to overlook the fuel filter; clogging can also cause misfires, and it should be replaced every 20,000 kilometers.


