Why Does An Ignition Coil Get Hot?

The age-old question has baffled car enthusiasts for years: why does an ignition coil get hot? Like any other electronic component, excessive current flowing through the ignition coil may cause it to overheat. This occurrence is due to the spark plugs and wires having more resistance than anticipated, resulting in a voltage-current overload on the ignition coil.

A heated ignition coil can lead to many issues without letting you know. But fear not; we’re here to explain all the details about this burning question. 

From understanding how an ignition coil works to identifying possible causes of overheating and ways to prevent it, we aim to provide you with a comprehensive guide on dealing with this issue effectively. So let’s get started!

How Does An Ignition Coil Work?

How Does An Ignition Coil Work

If you have the slightest knowledge about the electrical components of your car, it’s good to start with the basics. So, let’s first explain how ignition coils work in your car. 

An ignition coil is vital to an internal combustion engine’s ignition system. Its primary function is to convert the low voltage from the battery into high voltage the spark plugs need to ignite fuel in the engine cylinders. The process of how an ignition coil works is relatively simple but essential. 

The basic principle behind an ignition coil’s operation lies in electromagnetic induction that transforms electrical energy into magnetic energy and vice versa. As electricity flows through the primary winding, it creates a magnetic field around it. 

However, when this current stops flowing through the winding, the ignition coil creates another magnetic field that cuts across the secondary winding, inducing a high-voltage output that fires up your spark plug. 

When electricity flows through a wire, it generates heat due to friction caused by collisions between electrons and atoms. The same principle applies to an ignition coil. As electricity passes through its windings, countless collisions between electrons and atoms generate heat. Therefore, the more electricity passing through the coil, the hotter it will get.

Why Does An Ignition Coil Get Hot?

Now it’s time to focus on the elephant in the house. There are various reasons why an ignition coil may overheat. In essence, any factor that causes the ignition coil to work more strenuously or generate excessive electricity can elevate its temperature and potentially lead to its malfunction. 

However, for a more precise understanding, take a look at the following explanations of potential causes. 

Worn or Broken Coils Due to Aging

Typically, electronic ignition coils have a lifespan of approximately 10 years, with some lasting longer and others less. These components are subjected to challenging conditions such as temperature and vibration, which can take a toll on their functionality. 

Therefore, it is natural for ignition coils to deteriorate or malfunction with time, leading to overheating as the primary cause. Particularly, if your car has a conventional “wet” coil containing transformer oil, it is possible for the oil to either leak out or deteriorate over time. 

In this case, the solution is simply to replace it with modern, compatible dry resin coils, eliminating the need for oil filling altogether. While dry resin coils can also experience failure due to age or intense usage, it is significantly less common than wet coils. 

A coil that is failing even when functioning properly may become overburdened if the vehicle is left idling for extended periods on hot days, such as during summer traffic congestion. 

In such cases, turning off the engine to allow the coil to cool down can help it recover. However, repeated overheating can cause cumulative damage, making the coil increasingly susceptible to overheating.

Damaged Spark Plugs

The wear or damage of spark plugs can result in ignition coils functioning at a significantly elevated output. Maintaining optimal spark plug conditions can lessen the probability of ignition coil failure. 

The gradual deterioration of spark plugs leads to an increased gap between each firing, requiring the coil to generate a higher voltage to bridge the gap. This added pressure on the ignition coil may cause voltage overload, resulting in overheating and eventual failure.

Maintaining your spark plugs can mitigate this risk and keep your ignition system functioning smoothly. Additionally, the replacement of spark plugs can greatly benefit your vehicle. This particular component can be replaced as frequently as desired without any negative effects. 

It is also important to ensure that the spark plug wires are properly maintained by keeping them clean, dry, and securely fastened. Any signs of looseness, exposure to weather conditions, corrosion, or shorting can lead to abnormal resistance and should be addressed promptly.

Poorly Tuned Engine

A poorly tuned engine (if equipped with a distributor) is the second leading factor contributing to an overheating ignition coil. This occurs when the ignition timing is incorrect or if the point’s gap has lessened due to wear, resulting in prolonged energization of the coil. And ultimately, the ignition coils will be overheated.

It is important to note that the points gap and distributor timing are interrelated. Therefore, if the points are replaced or re-gapped, it is imperative to check and reset both statically and dynamically. This can be done by turning it over by hand and keeping the engine off and on for specific resetting processes. 

Faulty Components

In the event that your vehicle utilizes a fully electronic ignition system without a distributor, it is feasible for defective components to result in coil overheating. Typically, these systems include a variable dwell feature that safeguards against coil overheating during prolonged engine idling. 

However, based on your reference to a singular coil, your vehicle is unlikely to incorporate the modern fully electronic ignition system with multiple (dry resin) coil packs mounted directly atop the spark plugs. Regardless, identifying faults within this setup necessitates using electronic diagnostic tools.

What Happens When Ignition Coil Gets Hot?

Now that you know what causes ignition coil overheating and probable solutions for them. But the matter of concern is that most of us can’t anticipate what’s actually going on inside the ignition coil until it causes severe damage. 

Before you end up with such a scenario, it’s good to have an idea about the consequences or the warning signs of overheating ignition coils. Here are some common symptoms you should be wary of. 

Overheated Engine

If your engine temperature rises faster than normal, it could be an indication that your ignition coil is overheating. The ignition coil’s heat can cause a sudden surge in your engine’s temperature, potentially leading to additional issues if not promptly resolved. 

So, if you’re noticing your car getting a little too hot under the hood while you’re cruising or the car is in idling condition for an extended period, it’s probably time to give your ignition coil some attention

Misfiring and Stalling

Failing or overheating ignition coils often lead to stalling or misfiring of vehicle engines. As an ignition coil deteriorates, it loses its ability to provide sufficient spark and charge to the spark plugs, hindering the ignition of fuel necessary for proper combustion in the cylinders. 

This can result in stalling or misfiring of the engine. If left unaddressed, prolonged stalling could cause a complete shutdown of the car’s engine or an abrupt stop due to insufficient power generated by its cylinders, potentially resulting in extensive and costly damages.

Illuminated Check Engine Light

The Check Engine Light can serve as a warning sign for an overheating ignition coil. This indicator is activated when a fault is detected in one or more components of the vehicle’s emission system. 

Suppose the Check Engine Light remains illuminated while driving. In that case, it may suggest that one or more ignition coils are experiencing excessive heat due to the overvoltage caused by other malfunctioning electrical components in the vehicle.

Difficulty to Start the Vehicle

When your car struggles to turn on, it is often due to insufficient power being sent from the ignition coils. This results in difficulties for the spark plugs to generate the necessary electrical current within the cylinders for combustion. 

The lack of energy supplied by these components causes the engine to attempt continuously but ultimately fail until enough power can be built up through cranking. If this issue persists without any known solutions found after inspection, it can lead to financial and emotional distress.

Poor Fuel Economy

Are you experiencing a recent decline in fuel efficiency? This could be attributed to malfunctioning spark plugs that are not receiving sufficient electricity from an overheated ignition coil. 

As a result, your engine may require higher fuel consumption to compensate for the lack of spark energy necessary to maintain standard operating conditions. This can lead to increased expenses at the pump and decreased overall engine performance.

How Can You Prevent Ignition Coils Overheating?

To avoid overheating of the ignition coil, it is advisable to maintain a regular servicing schedule for your vehicle and replace spark plugs as required. 

Additionally, it is crucial to inspect the ignition system casing for any accumulation of dirt or corrosion on a frequent basis, as this can result in engine overheating and other associated problems. 

Lastly, it is imperative to utilize high-quality parts that conform to your vehicle’s specifications when replacing any system component to prevent issues such as overheating and eventual malfunctioning.

Final Words

An ignition coil gets hot due to the electrical energy that it converts into high voltage for the spark plugs. The excessive resistance in the coil’s windings and the current flow through them produces heat as a byproduct. Factors like overloading, age, and poor maintenance can cause higher temperatures in the coil, eventually leading to its failure. 

It is crucial to monitor the temperature of your ignition coil regularly and replace it if necessary to avoid any potential engine damage or safety hazards. Proper maintenance and periodic inspections of your vehicle’s ignition system can help prevent costly repairs down the road. Remember that a well-functioning ignition system is vital for efficient engine performance and reduced emissions.

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