What Causes Misfiring in Cylinders 1 and 3 of a Subaru Engine?

[DelAshley]

Misfiring in cylinders 1 and 3 of a Subaru engine is typically caused by issues in the ignition system or fuel supply system. When misfiring occurs, it is necessary to inspect both the fuel supply system and the ignition system. Symptoms of misfiring: Observe the exhaust pipe outlet; the exhaust gas flow will show obvious intermittency, accompanied by severe shaking of the exhaust pipe and a distinct "popping" sound. The primary symptom of misfiring is severe engine vibration. This happens because one or more cylinders are not functioning, disrupting the engine's balance. When the crankshaft reaches the point where a cylinder should ignite and provide thrust, the lack of combustion causes the RPM to drop. When the next cylinder ignites and provides thrust, the RPM rises again, leading to unstable engine speed and noticeable vibration. Hazards of misfiring: The engine's RPM and power output decrease. Fuel consumption and emissions increase. Wear and tear on moving parts accelerate, shortening the oil change interval. The engine load increases, causing more pronounced body vibration and a higher likelihood of sudden stalling.

[VanVivienne]

I've been driving a Subaru for over a decade and have encountered multiple misfire issues, particularly with cylinders 1 and 3 not firing, which is commonly caused by ignition system failures. Aged spark plugs are prone to malfunction, especially in Subaru's horizontally opposed engines where the deep-set spark plug position leads to heat buildup and rapid wear, resulting in failure to ignite or unstable ignition. Faulty ignition coils can also cause a cylinder to misfire—I've replaced them several times, and it's quite straightforward. I recommend testing with new spark plugs first; if there's no improvement, then check for loose wiring connections. The fuel system is also critical—clogged fuel injectors or fuel pump issues can prevent proper fuel delivery, leading to inadequate compression, which is more noticeable in uneven cylinder pressure. Subaru's design has weaker valve sealing, and air leaks can reduce compression efficiency. Don’t overlook diagnostic tools like an OBD scanner to quickly pinpoint the fault source. Prolonged issues can worsen engine vibration, damage the catalytic converter, and cause a spike in fuel consumption, which is troublesome. DIY repairs can save money, but if you're unsure, let a professional handle it—safety should always come first.

[Harris]

As a DIY enthusiast, I enjoy tinkering with my car. When dealing with a misfire in cylinders 1 or 3 of a Subaru, I start with simple checks. First, inspect the spark plugs and ignition coils – pull off the spark plug cap to check for proper ignition, and use a multimeter to measure coil resistance; replace it if the reading is too low. For fuel injector issues, listen for operational sounds, and use cleaner if clogged. A compression test is crucial – buy an affordable cylinder pressure gauge to test yourself. If readings fall below standard values (e.g., 90 psi), it may indicate valve seal leaks or worn piston rings. Subaru's horizontally opposed engines are prone to uneven carbon buildup, so regular intake system cleaning helps. Electrical faults like ECU signal errors can also falsely indicate misfires, so check for loose wiring harness connections. I've tried swapping parts to pinpoint issues, like moving a good spark plug to the misfiring cylinder to see if the problem shifts. DIY repairs save money but carry risks – don’t mess up critical components. Preventive maintenance like fuel and air filter care is key to keeping the engine running smoothly.

[Blanco]

As a regular car owner without much technical knowledge, I'm concerned about the safety of driving with misfires in cylinders 1 and 3 of my Subaru engine. The mechanic explained that possible causes could be dirty spark plugs or failing ignition coils leading to ignition failure. Clogged fuel injectors not spraying fuel properly is also common, especially when using low-quality gasoline. Subaru's horizontally opposed engine design makes valves prone to issues, potentially causing leaks that reduce compression and worsen misfire vibrations. When I experienced unstable idling, I took it to a professional shop immediately. They quickly diagnosed the problem using computer scanning - it's better not to tinker yourself to avoid complications. For prevention, pay attention to regular oil and filter changes to keep the system clean. Timely repairs are crucial as misfires create engine imbalance, increasing danger during high-speed driving and accelerating component wear. Safety first - leaving it to professionals gives peace of mind and saves effort.