What are the causes of catalytic converter damage and single/multiple cylinder misfires?
2 Answers
Catalytic converter damage and single/multiple cylinder misfires can be caused by the following factors: 1. Catalytic converter damage: Loss of surface precious metal activity; Blockage due to carbon deposits from ethanol gasoline usage, sulfur-phosphorus chemical compound sintering, lead-manganese metal deposit sintering, or ceramic substrate melting caused by engine exhaust flames; Prolonged exposure to high temperatures. 2. Single cylinder misfire: Ignition system failure; Engine malfunction issues, etc. 3. Multiple cylinder misfires: (1) Poor spark plug contact: Momentary ignition failure causing cylinder cut-off. (2) Excessive injector self-induced voltage: Resulting in sticking during the next operating cycle. (3) Poor heat dissipation: Inadequate transistor cooling in ECU causing ignition coil failure. (4) Insufficient cylinder pressure: Leading to ignition failure.
I've encountered quite a few cases of single or multiple cylinder misfires combined with catalytic converter damage. The main reason is that when misfires occur, large amounts of unburned fuel mixture enter the exhaust pipe and undergo secondary combustion in the three-way catalytic converter. The temperature can skyrocket to over a thousand degrees - the ceramic substrate inside the converter simply can't withstand such abuse. Common ignition system issues include spark plug carbon buildup preventing ignition, or ignition coil leakage causing specific cylinders to stop working; clogged fuel injectors can also result in overly rich mixture that doesn't burn completely. Additionally, faulty oxygen sensors can cause the ECU to miscalculate fuel injection quantity, increasing misfire risks. The most troublesome scenario is prolonged driving with misfiring cylinders - the catalytic converter sustains high temperatures that sinter and melt its honeycomb structure, blocking the exhaust. In such cases, you'll need to replace the catalytic converter and thoroughly inspect ignition coils and cylinder compression. My advice is to immediately stop and check when the check engine light flashes - don't let minor issues escalate into major repairs.
