What Causes Multiple Cylinder Misfires in Cars?

[StPaul]

Reasons for multiple cylinder misfires in cars are as follows: 1. Electrical wiring issues. 1.1 Aging or leaking electrical wiring, causing intermittent ignition faults. 1.2 Faulty ignition coils or spark plugs, resulting in poor ignition or conduction. 1.3 Loose wiring, exposed wires grounding, etc. 2. Fuel system issues. 2.1 Insufficient fuel injection pressure due to faulty electronic fuel pump. 2.2 Blocked or contaminated fuel lines, leading to poor fuel supply. 2.3 Faulty or clogged fuel injectors. 3. Engine-related issues. 3.1 Wear and aging, delayed maintenance, or use of substandard or low-quality engine oil. 3.2 Excessive wear causing cylinder pressure to fall below normal values. 3.3 Aging belts or incorrect ignition timing.

[LaSophie]

I've been repairing cars for over a decade, and multi-cylinder misfires are quite common. Most of the time, the problem lies in the ignition system - spark plugs with excessive carbon buildup or electrode erosion, aging high-voltage wires with leakage, or faulty ignition coils are frequent culprits. Last time I encountered a car shaking like it was dancing, and replacing the spark plugs immediately quieted it down. The fuel injection system also needs checking - clogged injectors causing fuel starvation or weak fuel pump pressure can also be issues. If the crankshaft position sensor fails, the control unit gets confused signals which easily leads to multi-cylinder shutdowns. Severe carbon buildup causing piston ring seizure can also cause this, making regular decarbonization essential.

[Ariana]

When working in a repair shop, it's often found that multi-cylinder misfires are usually systemic issues. The most common problem is a faulty ignition coil, where one bad coil can affect other cylinders. If spark plugs have reached the end of their lifespan with excessively large electrode gaps, they produce weak sparks and can even impact neighboring cylinders. On the fuel system side, a clogged fuel filter affects the fuel supply to all cylinders, while carbon buildup on fuel injectors causing uneven fuel spray is even more troublesome. In terms of sensors, a malfunctioning intake pressure sensor can throw the air-fuel mixture ratio completely out of balance. Loose electrical connectors causing poor contact can also create a chain reaction. Using a diagnostic tool to read fault codes combined with cylinder compression tests can usually pinpoint the source of the problem.

[LaPeter]

Start with the basics when diagnosing multi-cylinder misfires yourself. First, pull out the ignition coils to check for obvious cracks, then remove the spark plugs to inspect carbon buildup. Use a multimeter to measure the resistance of the cylinder wires—anything over 5 kilo-ohms is unacceptable. For fuel system checks, remove the fuel injectors and connect them to a 12V power source to test if the spray pattern is even. Don't forget to inspect the engine wiring harness connectors, especially the crankshaft sensor plug which is prone to oxidation. Last time, my car had all four cylinders failing due to poor connector contact, and cleaning the connectors fixed the issue.