In this article, we’ll take a close look at ignition coils – what they are, how they work, why they fail, and signs of bad ignition coil symptoms.
An ignition coil is a type of induction coil used in the automotive ignition system. Its purpose is to supply the spark plugs with the necessary current to ignite the air/fuel mixture in the combustion chamber. Commonly used in spark-ignition engines, coil assemblies are indispensable to engine operation.
The gasoline engine is an internal combustion engine that needs three things to operate: air, fuel, and an ignition source. In spark-ignition engines, the ignition source is the spark that’s generated by the spark plugs.
In older vehicles, the ignition coil is used in tandem with a timing device called a distributor. Often, a single ignition coil supplies current to multiple spark plugs. In modern vehicles, however, each spark plug has its own dedicated ignition coil called a coil-on-plug. Additionally, modern ignition coils have computer-controlled electronic timing systems in place of the distributor.
How do work?
Ignition coils function based on the principle of electromagnetic induction. Induction is the process by which electromotive force or voltage is generated by subjecting a conductor to a moving or stationary magnetic field. In the case of ignition coils, the magnetic field is stationary.
These are the symptoms of a bad ignition coil: Misfires – Check Engine Light: Misfiring is usually the first and most common symptom, and in most vehicles today, this will appear as a Check Engine Light. The misfire will either be on a particular cylinder, or random. Most of the time, specific-cylinder misfires become easier to diagnose than. Vehicles with bad ignition coils often run roughly. This means, when your vehicle is idling, you may notice a rough feel or sound. Your vehicle may also experience a drop in.
Coils are basically step-up transformers that convert low voltages from the car battery into thousands of volts. The voltage of the car battery is insufficient to create a spark strong enough to ignite the air/fuel mixture. High voltage current is necessary because of the compressed air/fuel mixture’s strong insulating properties.
A typical ignition coil system consists of two coils of wire called the primary and secondary windings. As the current passes through the primary winding, it energizes the winding to create a magnetic field around the coils. A timing device rapidly switches the current on and off to build up and collapse the magnetic field.
When the supply of current to the primary winding is cut off, the magnetic field collapses, creating a surge of current in the secondary winding. This current then travels through the electrode gap in the spark plug, creating an electrical arc, and igniting the air/fuel mixture.
How can you tell if an ignition coil is worn?
The ignition coils play a crucial role in engine operation. If one of the coils fails, a chain of faults will occur, including stalling, misfiring, backfiring, and startup problems. These failures are closely associated with the combustion process. There are several signs of a faulty ignition coil, and most of them are easy to recognize, as we’ll discuss below.
1. “Check Engine” light
The “Check Engine” light is the easiest way to spot bad or failing coils. Modern vehicles are equipped with an onboard computer that manages and monitors the vehicle’s intricate systems. When ignition coils are damaged or failing, the onboard computer will immediately engage the “Check Engine” warning.
2. Rough starts
Ignition coil failure may cause the engine to struggle upon starting or prevent it from starting at all. Starting the engine demands a substantial amount of energy from the battery. The coils are essential in meeting this surge in energy demand.. If the coils are defective, the engine may have trouble starting, or worse, won’t start at all.
3. Poor acceleration and rough idling
Typically linked to faulty sensors, inadequate fuel supply, and worn spark plugs, worn coils can also result in poor acceleration and rough idling. When your vehicle’s coils are worn, you may find that its engine is a bit hesitant during acceleration, there’s a noticeable lag in throttle response, and the vehicle may idle roughly.
4. Stalling
Another sign of a worn ignition coil is engine stalling. Stalling can be caused by several issues, including but not limited to: insufficient air, fuel starvation, excessive loads, and failure of combustion. When the coils cannot provide the necessary voltage to create a spark, the engine simply shuts down because it’s unable to produce enough force to propel the vehicle.
5. Misfires
Like stalling, engine misfires can be attributed to bad coils. An engine misfire results when there’s a combustion failure in one or more of the engine’s cylinders. Misfires are easy to notice, given the characteristic sputtering and struggling. In extreme cases, the engine may stall if several cylinders misfire simultaneously.
6. Backfires
While misfires happen inside the combustion chamber, backfires happen outside of the cylinders. Worm coils could lead to a failure in ignition in one or more of the cylinders. If the air/fuel mixture leaves the combustion chamber unburnt, the mixture may spontaneously combust in the exhaust (due to the heat in the exhaust). Backfires can cause severe damage to your exhaust system.
7. Poor fuel economy
Another symptom directly related to worn coil packs is poor fuel economy. Incomplete combustion leaves extra fuel unburnt. When the coils fail to provide sufficient current for the spark plugs to generate a spark, the chemical energy of the fuel isn’t converted into its usable form. When that happens, the amount of fuel consumed at a given distance is greater than when the coils are in perfect working order.
What causes ignition coils to fail?
Modern ignition coils are robustly constructed and can last years without being replaced. However, the fact that the coils have no service interval does not mean that they won’t fail. Like all parts, over time, coils wear down. Here’s why:
1. Excessive heat
Due to their location, coils are subjected to extreme heat from the engine. The amount of heat generated by the engine can stress the metal and plastic components of the coils. Metallic components of the coil tend to expand when subjected to heat. Thermal expansion reduces the ability of the coil to transform low voltages into high voltages.
Bad Ignition Coil Symptoms
2. Excessive vibrations
The engine produces significant amounts of vibration while running. Since the coils are installed directly over the spark plugs in the engine block, they are subjected to intense vibrations. Over time, the vibration loosens the connections in the coil assembly. Loose connections inhibit the flow of current between the conductive components of the coil.
3. Moisture and contamination
Ignition coil wear is often caused by moisture and contamination. Because the coils are installed in the engine, they may be contaminated by oil and coolant if seals are broken. Moisture can seep into the coils, where it corrodes or shorts its electrical components. Leaks caused by broken seals and gaskets can not only damage the coils, but they can damage the whole engine as well.
4. Excessive spark plug gap
For the spark plug to generate a spark, the current from the coils must bridge the gap between the plug electrodes. If this gap is wider than recommended, the coils will have to work harder to produce a current strong enough to span the increased gap. This stresses the coil components and accelerates wear.
5. Worn cables
In older vehicles, ignition cables deliver current from the coils to the spark plugs. Cables may be damaged due to ordinary wear and tear or because of the excessive heat inside the engine compartment. When the cables are bad, their resistance increases significantly. If left unattended, the increased resistance on the cable could burn out the ignition coil.
How do you know when you need new ignition coils?
If you encounter any of the signs associated with defective ignition coils, you should have your car checked out by a qualified mechanic ASAP. Early detection of coil failures prevents potential issues that may lead to costly repairs in the future.
With advances in manufacturing technology, modern coils are so durable that most manufacturers don’t set service intervals for them. As previously discussed, coils will eventually succumb to ordinary wear and tear, heat, vibrations, and contamination.
Aside from the signs commonly associated with failing coils, an onboard diagnostic (OBD2) scan tool can be used to check for defects. When plugged into the OBD2 port of the vehicle, the tool will scan the vehicle for faults in your car. If it detects a problem, the scanning tool will display a unique code that corresponds to the issue, along with a basic description.
It’s worth noting that the vehicle’s engine management system will not always engage the “Check Engine” light when the coils are damaged. In this case, scanning the onboard computer won’t yield a defect code. If all else fails, you may have to manually inspect the coils for cracks, contamination, and other visible defects.
How much does it cost to have the ignition coils replaced?
The cost of coil replacement depends on whether you are taking the vehicle to a mechanic or doing the replacement yourself. If you’re taking your car to a mechanic, you have two options: the dealership, or an independent mechanic. It’s essential to distinguish between the two since dealerships charge more than independent mechanics.
Coil packs usually cost around $60 to $200. The price varies depending on the make and model of your vehicle. Labor typically costs between $100 and $150 per hour. The whole process typically takes less than an hour. . If you opt to take the vehicle to the dealership, prepare for a bill shock and expect to pay twice the amount.
If you have plenty of time and don’t mind getting dirty, replacing the coils yourself is a viable alternative to taking your vehicle to a mechanic. You can save a lot of money on labor and you have the flexibility to choose which parts you’ll use. Coil replacement will only cost you about an hour of your time.
How are ignition coils replaced?
Replacing bad coils is pretty straightforward and can be done by an average person with basic automotive knowledge. We’ve outlined the general procedure below, just in case you decide to take a swing at it:
- Park your vehicle and switch off the engine.
- Pop open the hood and remove the engine covers, if installed.
- Allow the engine to cool for a few minutes (to avoid burning yourself).
- After the engine has cooled to a point where it’s comfortable to touch it with your bare hands, locate the coils on the engine. You can easily find them by tracing the harness that connects the coils to the onboard computer. Depending on your engine, the number of coils could vary from 4, 6, 8, 10, or 12.
- Remove the connector from each coil assembly. Note the positions of the connectors relative to the coils. This will come in handy later during installation.
- Carefully pull each ignition coil out of its seat above the spark plugs. If the coils are secured with bolts, you’ll need to remove the bolts to free the coils.
- Slide the new ignition coil into place and make sure that it’s pushed all the way in. Note: Most replacement coils come with pre-applied dielectric grease. If your replacement coils aren’t greased, apply dielectric grease to the boot of the coil assembly.
- One you’ve installed the coils, reconnect the connectors to the coils and make sure that each coil is properly coupled to its respective connector. Connecting a connector to the wrong plug may cause the firing order to go haywire and could cause catastrophic damage to your engine.
- Start the engine and check if the “Check Engine” light is blinking.
- Scan the computer for fault codes using an OBD2 scanner.
- If the “Check Engine” light doesn’t go off, and there are no fault codes from the scanner, take your vehicle for a test drive.
- Check for misfires, stalling, and other signs associated with bad coils. If there are none, congrats! You’ve successfully changed your vehicle’s coils.
Is it OK to drive with a bad ignition coil?
The answer is a resounding NO. While you can drive the vehicle with bad ignition coils, it’s strongly recommended that you only drive the car to the repair shop. Defective coils should be replaced without delay. Driving with bad coils can lead to dangerous driving situations and could potentially damage other parts of the vehicle.
Conclusion
Ignition coils are so important that your vehicle simply won’t run without them. Signs of worn coils shouldn’t be ignored, and coil issues are time-sensitive. Ignoring the problem will significantly accelerate wear on other components, and could lead to costly repairs in the future. Whether you decide to take your vehicle to a mechanic for repairs or replace the coils yourself (since the replacement procedure is pretty easy), you’ll need to act fast to prevent further damage.
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The first thing you do when you enter your car and about to move is to enter the car key In the ignition and turn it until you hear the starter sound. But what if you try to do this but nothing happened?
When the engine doesn’t start, the first thing may pop on your mind that you may have a bad battery or humid spark plugs or no injector pulse or you need to clean the distributor cap, etc.
There are many reasons that can make the car not starting. But the reason we’re going to talk about is a bit confusing and very hard to diagnose. It is having a bad ignition switch that prevents the car from getting started.
In this article, we’re going to get to know more about this fault, its signs, its diagnose process, and how to start a car with a bad ignition switch.
What are the signs of a bad ignition switch?
Before we dive deep into the signs of a bad ignition switch, we have to know more about the ignition switch assembly and operation. The ignition switch is where you put your key to start your car.
It is the main activator for the electrical systems in the car that allows the flow of the electrical pulses needed for the starter to give the first revolution in the engine.
It also gives the needed electricity for ignition systems such as ECU and ignition coil which gives the operative voltages to the spark plugs through the spark plug wire in correct firing order. All these ensure perfect ignition timing.
So if you have a bad ignition switch, you must have one or some of the following signs:
Hard to turn the key
If your vehicle is still working with the key, you may notice it’s not turning smoothly every time you try to start your car. You may feel that the key is wigging inside the keyhole or it’s stuck there. It means that there is serious damage in the ignition switch and it needs your attention before things get worse.
The vehicle cannot start
The first sign of a bad ignition switch is faulty in starting your car when turning on the key in the switch. This may happen due to the wear of the internal contacts of the ignition switch.
No starter motor sound
Another sign of a bad ignition switch is not hearing the sound of the starter motor when you turn the key. You can differentiate between bad starter motor or bad ignition switch by not hearing any clicking coming from the starter.
Stalling vehicle
If your car stops working suddenly while driving with no warning, this means that you may have a fault in the ignition switch.
Stuck steering wheel
In the ignition switch, there is a mechanical lock for the steering wheel. It stops the steering wheel in order to secure the car while parked. If you have problems with the steering lock, this means you have to check the ignition cylinder for maintenance.
How to start a car with a bad ignition switch?
So, if you are facing problems with car starting and you are sure you have a problematic ignition switch, here is how to bypass ignition switch to start the car. All you need are proper tools and you’ll be able to start your car easily with some procedure.
Hotwiring
If your car produced before the mid-90s, then this trick might work well for you. Once you get in the car, locate the steering wheel column. Then remove the plastic cover that secures all internal parts. That should expose all necessary parts.
After that, locate the wiring harness connector. Locating the specific connector may be somehow hard to do because there are a lot of cables and wires in this area. But most of the time it is located at the centre of the steering column. The other wires, cables, and connectors are related to the lights control wipers and other accessories.
Then you have to locate battery, ignition, and starter connectors. The yellow and brown wires are related to the ignition. The red ones are for the battery. Strip down the battery wires an inch down from insulation and twist them together.
Then connect ignition on/off the wire to the battery wire and you’ll see that the lights came on and the electrical parts started working. Now, to start the engine, strip the starter wire down half-inch and touch it to the connected battery wires. Now the engine must startup. So, try to rev up the engine for a while.
The drill and screwdriver
This trick may also work but beware because it can damage the Ignition switch completely. It also will give you the knowledge of how to start a car with a broken ignition switch.
So, you have to locate the keyhole and get a metal drill and then drill into the keyhole in the same length of the key. This will destroy the internal pins of the ignition cylinder. Then get the screwdriver and put it into the keyhole as it is the key and turn the ignition and the car should startup.
Jumper cables
Open the hood of your car and locate the ignition coil and the battery. Then using a jumper cable, connect the positive terminal of the battery to the positive side of the coil. This will give power to the dashboard which is needed to start the engine.
Then locate the starter solenoid and connect the solenoid to the positive battery terminal. Then unplug the ignition switch wiring from the solenoid. Using a screwdriver, short the solenoid’s positive terminal to the post where the ignition switch connects.
This will activate the solenoid and the car should startup.
How do you test an ignition switch?
We know that An ineffective ignition switch can cause many errors. We’ve already known how to start without an ignition switch and how to bypass it. So, it is time to know whether my ignition switch is in good condition or not.
In this section, we’re going to diagnose the ignition switch faults and know how to test the ignition switch with a multimeter or with a test light.
As we knew before that the main function of the ignition switch is to provide electricity to the ECU and the ignition coil. So, it has two wires coming out of it. One goes to the ECU and the other to the ignition coil module. The first thing we’ve to detach the switch from its slot.
Using multimeter:
You’d better start testing by getting the switch to the OFF position. Connect the positive probe of the multimeter to the switch’s power feed wire and connect the negative probe to any unpainted metal in the car.
Now turn the key to the RUN position and set the multimeter to measure voltage. Read the voltage. If you get any result showing less than 90% of the battery voltage, you may have a fault in the ignition switch.
Using test light:
If you don’t have access to a multimeter, don’t worry. You can still test your ignition switch using a 12 V test light. Turn the key to the OFF position then disconnect the module’s cable connector. After that, disconnect starter motor solenoid’s S terminal, this will prevent the engine from cranking even when turning them into RUN position.
Turn the key to the RUN position. Connect the red wire to the test voltage. Then do the same at the ignition coil’s battery post. Then put the key to start position and connect the ignition switch white wire.
This should make the lamplight on. If there is no light, then there is a faulty in the switch.
How to fix a bad ignition switch?
In this section, we will go through the problems of the car ignition switch. We will learn more about ignition lock cylinder problems and how to fix it. Besides, we’ll learn how to avoid it from happening in the future.
Bad Ignition Starter Switch
One of the widely known problems related to the ignition switch is the steering wheel safety lockout. It’s not allowing the steering to turn when the key is in the OFF position. Cars equipped with power steering mechanical pump lose pressure and forces steering to lockup pin when you try to turn the engine wheel and your engine is off.
To release the steering wheel lock, you need to turn the steering wheel and turn the ignition key at the same time.
If the dirt and debris get their way inside the ignition switch, they can cause the key to stuck and not turning. In this case, the lock gets jammed and can’t release the steering wheel. The first try, in this case, is to use some rust remover product and apply it with a pressure nozzle through the keyhole.
If the problem is not fixed, then you have to try another method which is using a light hammer and try to make several light taps on the key. But you have to be gentle. Do not break the key in the switch.
So, if all these tries came to an end and nothing fixed, the ignition lock cylinder must be replaced. This happens because the internal parts of the switch wear with time.
Troubleshoot the Ignition Switch YouTube Video
Final Words
The ignition switch is the most used device in the car that should always be in good condition to always have a good start. Like any other switch or module in the car, it requires service. It is exposed to tear and wear with time.
So, apply the tips and tricks in this guide to self-diagnose faults and fix them. But if you got stuck in anything, don’t hesitate to seek professional help. This will save you from breaking anything or having a bigger problem.
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