Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.
A Bad Crankshaft Position Sensor
The crankshaft position sensor monitors the position and rotational speeds of the crankshaft. Without the crank sensor, the engine control module (ECM) wouldn't know when to fire the fuel injectors and ignite the spark plugs.
If the car cranks when you turn the key, but the engine won't start, it could be because fuel isn't getting to the engine. One potential reason for this could be dirty fuel injectors. Over time, the fuel injector nozzles can become clogged with rust, corrosion or debris.
In terms of operation, the spark plug is connected to the high voltage generated by an ignition coil (by way of a conventional distributor or by way of an electronic means). As electricity flows from the coil, a voltage difference develops between the center electrode and ground electrode on the spark plug.
A good spark will be blue-white and will be plainly visible in daylight. If a good spark is present, the problem is probably not in the ignition system. Check the fuel system and/or stark timing. Weak sparks are orange or red and may be hard to see in daylight.
Hard Starts and Stalling
If an ignition coil is malfunctioning and not delivering the required voltage to the spark plugs, you will find it hard to start the engine. If your vehicle stalls when you stop and even shut off completely, it could be a bad ignition coil sending irregular sparks to the spark plugs.
If the ignition relay shorts, burns out, or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system. This will cause the vehicle to immediately stall due to fuel and spark being cut off.
Vibrations can damage ignition coil windings and insulation causing shorts or breaks in the secondary windings. The overheating of ignition coils can hinder their ability to conduct electricity. Wear and tear is a common reason for ignition coils failing.
The low voltage primary circuit operates at battery voltage (12 to 14.5 volts) and is responsible for generating the signal to fire the spark plug at the exact right time and sending that signal to the ignition coil.
As a camshaft position sensor starts having problems and weakens, the transmitted signal to the car's computer weakens as well. This means the eventually the signal is so weak that it will not allow the car to start since there will be no spark from the ignition.
The ESC module is one of the components that directly controls engine spark, so if it fails, it can leave the vehicle without spark. A vehicle without spark may still crank, but will not be able to start or run.
Without the crank position signal, the engine control module (ECM) can't detect where the cylinders are or how fast they're moving. If you have crankshaft sensor issues, the ECM can't synchronize fuel injection, spark ignition (for gasoline engines) or control variable valve timing.
As mentioned, your vehicle would not function without the ignition coil. This coil is essentially a powerful conductor that turns the voltage from your battery into the strong energy needed to jump the spark plug. This ignites the air and fuel mixture within the engine.
Ignition coils tend to fail because of bad spark plugs or plug wires. If your vehicle's fuel-to-oxygen mixture is either rich or lean, therefore, your ignition coils may fail prematurely. Additionally, engine heat and vibrations can cause damage to ignition coils.
Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.
Thus, the short answer to what does a battery do after the auto engine starts, is it keeps feeding power to the coil. The longer answer is it also supplies smoothed lower voltage to secondary systems.
Dirty, misfiring, or worn spark plugs can damage the ignition coil, so plan to have your spark plugs changed when recommended. On older car, trucks, and vans, it's a good idea to have the spark plugs changed every 30,000 miles, especially if you drive a much older car.
If your Spark Plugs are failing your engine will sound rough and jittery when running at idle. This can cause vibrations to resonate through the vehicle which could cause further costly damage.
Symptoms of misfiring spark plugs include rough idling, uneven power when accelerating, and an increase in exhaust emissions.
Your alternator powers your vehicle's spark plugs, the parts that light your gasoline to start your engine. If your alternator is not working, your spark plugs will not be able to function either, leading your car to struggle to start up.