What are the causes of multi-cylinder misfires that damage the catalytic converter?
3 Answers
The causes of multi-cylinder misfires that damage the catalytic converter are as follows: 1. Ignition system failure: The vehicle's ignition system has a malfunction, such as ignition coil leakage, excessive spark plug gap, or faults in the ignition coil itself and its peripheral circuits. Remove and inspect, swap the spark plug high-voltage pack, check the wiring, and observe the ignition waveform using an oscilloscope. 2. Fuel system failure: The fuel system has a malfunction, such as poor injector or atomization, fuel pressure regulator issues, fuel pump problems, or clogged fuel filter. 3. Intake system failure: The intake system has leaks, incorrect valve timing, improper valve clearance adjustment, weak or broken valve springs, or valve carbon buildup.
I've seen quite a few cars suffer from this issue. Multi-cylinder misfire means the ignition in several cylinders fails, causing unburned fuel to enter the catalytic converter, where it burns at high temperatures and eventually destroys the converter over time. Common causes include clogged old fuel injectors, failed ignition coils, or control module errors, such as crankshaft position sensor failures leading to multi-cylinder misfires. The last time I went to the repair shop, the mechanic opened it up and found the converter had turned to ashes. Repairs can easily cost 10,000 to 20,000 yuan—really painful. Actually, just pay attention while driving: regularly maintain and check spark plugs and wire connections, read error codes with a diagnostic tool before replacing parts, and don’t let small issues escalate into big disasters.
As someone who frequently helps friends with car repairs, I've encountered multiple similar cases. Multi-cylinder misfire occurs when ignition fails in multiple cylinders, causing unburned gasoline to enter the catalytic converter. The high temperatures inside can melt or detach the catalytic metals, rendering it ineffective. The key causes fall into several categories: fuel injector leaks causing excessive fuel delivery leading to incomplete combustion due to improper air-fuel ratio; secondly, ignition system issues such as excessive spark plug gap or aging high-voltage wires; and also engine control unit malfunctions sending incorrect commands. This not only damages the catalytic converter but may also double fuel consumption and pose safety risks. For DIY inspections, I recommend starting with simple spark plug replacements and upgrading the control system when necessary. Maintaining good habits can save you from expensive repair bills.
