What causes the ignition device of BMW 5 Series to fail to start?
2 Answers
BMW 5 Series ignition device fails to start for the following reasons: Excessively rich air-fuel mixture: If the engine has difficulty starting when hot but starts normally when the accelerator pedal is fully depressed (no fuel injection when fully depressed), it indicates an excessively rich air-fuel mixture. In this case, the air filter element can be removed to release some of the accumulated rich mixture in the intake tract. Additionally, removing the filter element reduces intake resistance; the lower the intake resistance, the leaner the air-fuel mixture becomes, allowing normal starting. Focus should be on checking whether the charcoal canister solenoid valve is stuck in the open position. Excessive carbon deposits in the throttle system and bypass air passage: If the accelerator pedal feels much heavier than usual when pressed for the first time each day, and the engine has difficulty starting, but starts normally when the pedal is slightly depressed, it indicates excessive carbon deposits in the throttle. These deposits block the throttle, causing starting difficulties. Slightly depressing the accelerator pedal during startup ensures sufficient air intake, allowing normal starting, but releasing the pedal while driving will cause the engine to stall immediately. The throttle system and bypass air passage should be cleaned promptly, and recalibrated after cleaning to restore normal operation. Poor battery terminal contact in cold weather: Over time, white crystalline particles form on the battery terminals, causing battery leakage and preventing the engine from starting after parking in cold weather. Pouring hot water over the crystalline particles on the terminals can allow normal starting. During maintenance, use sandpaper to remove the white crystalline particles from the terminals and apply grease to resolve the issue. Short circuit in the ignition coil: This can cause difficulty in starting the engine, poor acceleration, black smoke from the exhaust pipe, and a sharp increase in fuel consumption. Replacing the faulty ignition coil can resolve the issue.
Last time my BMW wouldn't start, it was really frustrating. There are quite a few common causes. Battery aging is the prime suspect - if the dashboard lights dim or you hear clicking when starting, it's probably a dead battery. You can try jump-starting with a friend's help. Starter failure is also common; when it's bad, the car will be completely silent with no response. If the ignition switch is worn out, turning the key will feel like it's spinning freely. Sometimes the anti-theft system acts up too - if the key battery is weak, the car might mistake it for a thief. Electronic modules like the ECU are tricky to fix yourself and require professional diagnosis. From my experience, always check the battery and key first - try replacing them, don't delay to avoid bigger trouble, especially since breaking down on the highway can be really dangerous.
