What does it mean when the fuel measurement system for cylinder bank 1 is too lean?
3 Answers
Cylinder bank 1, the fuel measurement system is too lean at idle speed, which is basically due to an intake system leak, with a focus on checking the exhaust gas valve. Specific details are as follows: 1. Reasons for the fuel measurement system being too rich at idle speed: The intake air sensor signal is abnormal. The correction signals for fuel injection from the coolant temperature sensor and oxygen sensor are abnormal. The fuel pump pressure is too high. There is leakage in the fuel injectors. 2. When engine knock is detected: Monitor changes in combustion chamber pressure; Detect the vibration frequency of the engine block. Monitor the combustion noise of the air-fuel mixture.
With years of experience in car repairs, I've encountered many similar faults. 'Bank 1 Too Lean' typically indicates an overly lean fuel mixture—too much air and too little fuel—with multiple potential causes. The most common issue is small cracks in the intake manifold or vacuum hoses allowing air leaks; inspect rubber hose joints for aging or cracks. Fuel system problems could also be at play: clogged fuel injectors failing to deliver sufficient fuel, or a dirty fuel pump filter restricting supply. The electronic control system might malfunction too: faulty oxygen sensors or mass airflow sensors sending incorrect signals, causing the engine control unit to mistakenly reduce fuel injection. Don't underestimate this—the car may shake, run unevenly, spike in fuel consumption, or even trigger a warning light. If you're handy, start by reading trouble codes with a diagnostic tool to pinpoint the issue. Otherwise, seek professional repair to avoid damaging the catalytic converter or engine internals. Regular maintenance like fuel system cleaning can prevent such problems.
My car had this issue last year, the engine always jerked at low speeds, and the diagnosis said cylinder bank 1 had a lean fuel mixture. Experience tells me this is mostly due to air sneaking into the mixture: for example, if the intake pipe joint is loose or cracked, air gets in and dilutes the fuel. It could also be that the fuel injectors are clogged with carbon deposits, leading to insufficient fuel injection. I remember it got much better after replacing the fuel filter, and I usually add some cleaner to the fuel to prevent clogging. Don't wait too long, driving like this for an extended period can cause the engine to misfire and damage the cylinder block, costing both money and time. For safety, stop and check or send it for repair as soon as you notice symptoms, and always pay attention to changes in fuel consumption and the feeling of jerking while driving.
