Why does it keep reporting misfire in cylinder 4?

[KylieLynn]

There are several reasons for misfire in cylinder 4: 1. Poor spark plug ignition. 2. Piston ring damage causing low cylinder pressure. 3. Internal damage to the ignition coil. 4. Incorrect timing mechanism or skipped teeth. 5. Engine computer damage or fault codes. Additional information is as follows: 1. Misfire in cylinder 4: It is recommended to inspect the spark plug, ignition coil, high-voltage wire, fuel injector, and cylinder pressure of cylinder 4, as well as check for any air leaks in the intake manifold of cylinder 4. 2. Composition of a four-cylinder engine: The engine block mainly consists of components such as the cylinder block, crankcase, cylinder head, and cylinder gasket. The basic principle of a four-cylinder engine is to convert the thermal energy of gasoline (diesel) into mechanical energy by pushing the piston to do work when the gas expands during combustion in a sealed cylinder.

[StZachary]

As a veteran mechanic with over a decade of experience, four-cylinder misfire error codes are quite common. Worn spark plugs are the prime suspect - just check the electrode erosion after removal. Cracked ignition coil boots can also cause electrical leakage, especially noticeable during rainy seasons. When injectors are clogged or have poor atomization, the ECU reports misfires - cleaning them is cheaper than replacement. Low cylinder compression demands attention, as valve leaks or piston ring wear spell trouble. I often advise owners to first check the misfire counters in the fault codes. Frequent cold-start misfires may indicate crankshaft position sensor signal drift. A quick fix is the coil swap test at a roadside shop - whichever cylinder's problem moves after swapping coils indicates which coil needs replacement.

[VonTalia]

I encountered this issue with my old Bora, sharing some practical experience. If the four cylinders consistently report misfires, don't delay. Long-term cylinder deficiency can flood the spark plugs, causing gasoline to flow into the engine oil and dilute lubrication. First, check if you've recently refueled at a budget gas station – clogged injectors from poor-quality fuel are common. For DIY solutions, you can buy a bottle of fuel injector cleaner, mix it into the fuel tank, and drive at high speeds. If carbon buildup is severe, removing and cleaning the throttle body shows immediate results. Test aging ignition wires with a multimeter; replace if resistance exceeds 5 kilohms. If you notice a fuel smell during ignition, focus on checking for ignition coil leakage, as rubber degradation and cracking are common under high engine bay temperatures.

[HeidiLynn]

Those who are into car modifications know that four-cylinder misfires often occur after electrical circuit alterations. Installing a voltage regulator can interfere with ECU signals, or haphazardly connecting high-power electrical devices causing voltage fluctuations can lead to false alarms. Oxidized wiring in older cars is particularly troublesome—I've dealt with cases where connector pins developed verdigris. Choosing the wrong spark plug heat range can be fatal; using low heat range plugs in turbocharged cars can directly melt the electrodes. After modifying the intake system without reprogramming the ECU, the air-fuel ratio becomes imbalanced, and misfires are guaranteed during hard acceleration. It's recommended to use a diagnostic tool to monitor real-time data streams, paying attention to long-term fuel trim values exceeding ±10%, which indicate a mixture issue. Switching to iridium spark plugs can alleviate the problem, but a permanent fix requires ECU tuning.