Ignition System Quiz Questions And Answers

Ignition coils are devices used in the ignition system of internal combustion engines to convert the low voltage from the battery into the high voltage needed to create a spark in the spark plugs. They achieve this by utilizing the principle of electromagnetic induction, where a changing current in the primary coil induces a high voltage in the secondary coil. This process involves stepping up the voltage, making ignition coils function as step-up transformers.

As engine rpm increases, the ignition timing must advance. This is because at higher engine speeds, the air-fuel mixture needs to be ignited earlier in the compression stroke to ensure optimal combustion and power delivery. Advancing the ignition timing allows for a more efficient and complete combustion process, maximizing engine performance.

Most vehicles today use the coil-on-plug type of ignition system. This system eliminates the need for a distributor and instead places an ignition coil directly on top of each spark plug. This design provides better ignition timing control, improved fuel efficiency, and reduced emissions. It also allows for easier maintenance and troubleshooting since each coil can be individually tested and replaced if necessary. Overall, the coil-on-plug ignition system is the preferred choice for modern vehicles due to its efficiency and performance benefits.

When the driver turns the key to the start position, an electrical connection is made between the vehicle battery and the primary winding of the ignition coil. The primary winding is responsible for receiving the electrical current from the battery and creating a magnetic field. This magnetic field is then used to induce a higher voltage in the secondary winding of the ignition coil, which is connected to the spark plugs. This higher voltage is necessary for creating the spark that ignites the fuel-air mixture in the engine cylinders, allowing the engine to start and run.

A spark plug must create a high-voltage spark to ignite the compressed air-fuel mixture in the cylinder. This occurs as the piston reaches top dead center (TDC) during the compression stroke. This ignition causes combustion, which forces the piston down, powering the engine. The spark is not needed during the exhaust, intake, or ignition strokes.

The center electrode is the hottest part of the spark plug because it is the part that receives the electrical current from the ignition system and generates the spark. As the electrical current passes through the center electrode, it creates a high level of heat due to the resistance of the metal. This heat is essential for igniting the air-fuel mixture in the engine's combustion chamber. The ground electrode, insulator, and metal shell also play important roles in the spark plug's function, but they do not generate as much heat as the center electrode.

The ignition system in a vehicle needs to convert the low voltage and high current from the battery into high voltage and low current to create a spark for the combustion process. The component responsible for this conversion is the induction coil. The induction coil uses electromagnetic induction to step up the voltage and reduce the current, allowing for the creation of a high-energy spark. The other options, such as the ballast resistor, advance mechanism, and condenser, do not perform this specific function in the ignition system.

Tech A is not correct because while it might be convenient to set the spark plug gap on all plugs at once, the best practice is to check and set the gap individually as you install each spark plug. This ensures accuracy and proper installation for each cylinder.

Tech B is also not correct because although many modern spark plugs come pre-gapped, it is still important to check the gap before installation. Handling and packaging can sometimes alter the gap, and the specified gap can vary between different engines.

Therefore, the correct answer is "Neither Tech A nor B."

The primary winding of the ignition coil has approximately a few hundred turns of enameled copper wire. This is because the primary winding is responsible for generating a high-voltage spark, and a few hundred turns of wire allow for sufficient voltage buildup and energy transfer to the secondary winding. Having too few turns would result in a weak spark, while having too many turns would lead to excessive resistance and inefficient energy transfer. Therefore, a few hundred turns strike a balance between voltage output and efficient operation.

Tech A is correct. The ignition coil can be tested with an ohmmeter. An ohmmeter measures the resistance of the coil, which can help determine if there is an issue with the coil. On the other hand, an oscilloscope is not typically used to test the ignition coil. It is used to measure and analyze electrical waveforms, which is not necessary for testing the coil. Therefore, Tech B is incorrect.

Tech A is correct in stating that ignition coils are essentially transformers, as they convert the low voltage from a car's battery into the high voltage needed to create a spark at the spark plug. This high voltage is necessary to ignite the air-fuel mixture in the engine. Tech B, however, is incorrect because it is the secondary side of the ignition coil, not the primary side, that delivers the high voltage spark to jump the plug gap. The primary side handles low voltage, which induces a high voltage in the secondary coil to generate the spark.

The collapse of the magnetic field inside the ignition coil happens when the current to the primary winding is interrupted. In an ignition coil, the primary winding is a coil of wire that, when supplied with current, creates a magnetic field. When this current is suddenly interrupted (usually by the ignition control module or the electronic control unit), the magnetic field collapses rapidly. This rapid collapse induces a high voltage in the secondary winding of the coil, which is then sent to the spark plug to ignite the air-fuel mixture in the cylinder.

The correct answer is "required voltage" because it refers to the specific amount of voltage that is necessary to create a spark and jump the spark plug gap. This voltage is essential for the ignition process to occur in an internal combustion engine. The other options, such as "available voltage" and "induced voltage," do not accurately describe the specific voltage needed for this purpose.

Tech B is correct. A secondary ignition shock does not have enough current to kill a person. While a secondary ignition shock can be painful and potentially cause injury, it is not typically lethal. The primary ignition system, on the other hand, carries enough current to be potentially fatal.

A waste spark ignition system is a type of ignition system where two cylinders share one ignition coil. In this system, each coil fires two spark plugs simultaneously: one in the cylinder that is on the compression stroke and the other in the cylinder that is on the exhaust stroke. The spark in the exhaust stroke is the "waste spark," as it does not ignite any fuel-air mixture. This setup is simpler and more cost-effective than a system with individual coils for each cylinder.

Tech A is correct. A defective crankshaft or camshaft position sensor can indeed prevent an engine from starting. These sensors are responsible for providing the engine control module (ECM) with information about the position and speed of the crankshaft and camshaft. If the ECM does not receive this information, it may not be able to properly control the ignition and fuel systems, leading to a no-start condition. However, Tech B is incorrect. Just because a diagnostic trouble code (DTC) indicates a problem with the sensor does not necessarily mean that the sensor needs to be replaced. The DTC could be triggered by a wiring issue, a faulty connector, or even a problem with the ECM itself. Further diagnostic testing is required to determine the root cause of the problem.

Both Techs A and B are correct. A Hall-effect sensor and an optical-type sensor can both be used in an electronic ignition system. The Hall-effect sensor uses the principle of the Hall effect to detect changes in magnetic fields, while an optical-type sensor uses light to detect changes. Both sensors can effectively detect the position of the crankshaft or camshaft in an electronic ignition system, allowing for accurate ignition timing.

On a lab scope, the spark voltages for all the cylinders as they fire in sequence are displayed in what is called a parade pattern. This pattern allows technicians to compare the ignition characteristics of all cylinders side-by-side and identify any discrepancies or misfires. It is useful for diagnosing engine performance issues related to ignition.

Both Techs A and B are correct. Tech A is suggesting using a spray bottle and water to test for defective ignition wires, which is a common method known as the "water spray test." This test involves spraying water on the ignition wires while the engine is running, and if there is a defective wire, it will cause the engine to misfire or stall. Tech B is suggesting using a grounded test lead, which is another valid method to test for defective ignition wires. By connecting the test lead to a good ground and touching it to each ignition wire, any faulty wire will cause a spark to jump to the ground, indicating a defect.

Neither Tech A nor Tech B is correct. The crankshaft sensor is used to monitor the position and rotational speed (RPM) of the crankshaft, which helps the engine control unit (ECU) manage ignition timing and fuel injection, not vehicle speed. Meanwhile, the camshaft sensor monitors the camshaft's position to help the ECU control the timing of fuel injection and ignition, but it does not control fuel pump speed. The vehicle speed sensor (VSS) is typically responsible for determining vehicle speed, and the ECU controls fuel pump operation based on engine needs.