Engine misfires are caused by different reasons, and one of them is bad ignition coils. The ignition coils provide good spark to your distributor. They are made to last quite a while but with use and age, they become worn and do not function as they should. The most typical causes of coil failure include a dying battery, corrosion from air flow, and exposure to chemicals such as lubricants and solvents used around the engine. When your BMW X5 ignition coils are worn out, they cause misfires as well as a number of other engine problems. Take a look at the following symptoms of bad ignition coils.
When you find considerable difficulty in starting your car, it may be the ignition coils going bad. Also, bad coils can still provide current to the spark plugs so they can burn the fuel, but the current is no longer enough. That's why stalling is a big probability. A totally failed coil, in the other hand, will prevent the engine from starting. And when the coils completely fail while the car is running, it will suddenly stop working altogether, leaving you right in the middle of the road. In this case, even if you jumpstart the battery, your X5 will not work at all.
Because of the deficient current transferred from the battery to the spark plugs, the engine may not receive the sparks needed to keep it running. This results in the rough idle you may notice like when waiting for the green light and in the jerky acceleration when you try to speed up while driving. Besides this, the other electronic accessories such as the radio and the lights will be weaker or dimmer.
Another symptom of bad ignition coils in your BMW X5 is the black smoke and the smell of gasoline that comes out from the exhaust. This is because of the decrease in fuel efficiency. With the lack of power to burn the fuel, it comes out of the other end not completely used up. This consequently leads to higher expenses on fuel.