You must check the coil pack for continuity using an ohm meter. Make sure you have an idea of the coil pack’s approximate ohm values. To figure out what the mega ohms reading on the coil pack should be, look up your car’s engine on the Internet or buy a Chilton’s or Haynes handbook.
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A 12 volt coil should have how many ohms?
Make sure the positive terminal has 12V before checking the coil. Once you’re certain that’s the case, pull the wire out of the distributor’s center and hold it a few centimeters away from the center terminal. There should be a bright blue spark when the engine is started. If the yellow color appears weak and thin, the coil might be about to burst. As sometimes problems may only become apparent when the coil warms up, you might want to repeat this test as well as the one below in both hot and cold conditions.
Setting the voltmeter:
- utilizing a voltmeter Connect the black probe to your multimeter’s COM port.
- The VmA port should accept the red probe.
- Turn on your multimeter and select the resistance setting.
- The symbol represents the resistance in ohms.
- The majority of multimeters do not automatically range, therefore you must set the proper range for the resistance you intend to measure. Start with the highest setting if you’re unsure.
Attach the positive and negative probes of the meter to the negative and positive terminals on the coil after all wires have been removed from those terminals. A resistance value of at least 3-4.5 ohms is required. A defective coil will display a reading greater than 3-4.5.
After that, connect either the positive or negative terminal of the meter’s red or black lead to the coil’s center. A bit less than 9500-10000 Ohms is acceptable, but not more. The coil has to be changed if the reading is 10500 or above.
Rerun this test with the coil both cold and not operating, as coils occasionally malfunction only when they are heated.
How does a coil pack degrade?
The most common cause of ignition coil failure is faulty spark plugs or plug wires. Therefore, your ignition coils may experience premature failure if the fuel-to-oxygen ratio in your car is either rich or lean. The heat and vibration from the engine might also harm the ignition coils.
How durable are coil packs?
Coil packs typically last up to 5 years or 120,000 miles before needing to be replaced. Coil packs have a lengthy lifespan, but continual exposure to heat and friction can inevitably shorten their lifespan. Carbon buildup may also cause harm to the coil pack.
It usually doesn’t cost more than $300 to replace your car’s coil pack when the time comes.
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What should the coil’s voltage be?
If the coil contains a ballast resistor, the voltage that reaches it may be roughly 7 volts rather than 12 volts. Although most current cars have a resistor in the ignition system to help with starting, most electrical equipment operates on 12 volts. Instead of 12 volts, a ballast-resistor system’s coil is rated for 7-8 volts.
What voltage is a 12 volt coil capable of producing?
Even among those of us who are quite versed about cars, the ignition system occupies an almost magical space. a space filled by the Pogue Carburetor and the quasi-turbine engine’s intricate workings. Although we are aware of the fundamentals, much of what actually occurs “in there” is a product of our imaginations.
Essentially, an ignition coil is an electromagnet. It has an iron core that has a few hundred times of reasonably thick wire (primary winding) wrapped around it. Between the iron core and primary winding, there is a secondary winding of 200 feet of thinner wire coils. When electricity passes through the primary winding, a magnetic field is formed that contains this winding.
Current flows through the primary winding when the ignition is turned on and the breaker points are closed, producing a magnetic field. The magnetic field falls and the primary current flow ceases when the points open. As a result, the secondary winding receives current. By acting as a transformer, the coil raises the voltage. The 12 volts you put into the coil’s primary side will exit the secondary side as 30,000 volts if your car runs on a 12 volt battery.
A high-tension wire that resembles a brief spark plug cable that runs to the distributor tower transports the high voltage away from the coil. The coil could be connected directly to the spark plug in a one-cylinder engine, but in a multi-cylinder engine, a distributor is required to direct the high-voltage secondary current and burn each spark plug at a predetermined time. It is known as “ignition timing.”
The primary winding of a coil with primary and secondary terminals is attached to the terminal on the coil that is labelled “+ or “Bat if your automobile uses a negative ground. This terminal is the one that the battery’s voltage is applied to. The primary wire is then wound around the iron core before being connected at the opposite end to the terminal with the “-” or “Dis” markings. The breaker points inside the distributor get voltage from this terminal. The opposite is true of positive ground.
The majority of ignition coils are durable and dependable, but a weak coil can wreck havoc inside the car. Without providing high power to the spark plugs to ignite the air-fuel mixture, a car cannot be driven smoothly. Secondary winding flaws are to blame for the majority of coil failures. Between the two windings, there is sometimes a thin lacquer insulator that deteriorates. Sometimes the ground is no longer isolated from the windings. Heat and vibration are frequently at blame for these coil issues.
A abrupt failure could occur as a result of damaged connections or broken windings inside the coil. Coil issues, however, most frequently manifest as difficult starting, persistent high-speed misses, or a steady deterioration in ignition system performance.
The little scope on a Sun machine or an ohmmeter (the majority of coils will read around 8,000 ohms) can be used to test coils. The scope will display a “heartbeat pattern” for a typical coil, a “bumpy L” pattern for shorted windings, and a flat horizontal line for open windings.
By placing one probe of a cheap test lamp on the metal container and the other on the primary and high-tension terminals, any coil with a metal housing can have its windings checked for grounding. If the tester lights up or you notice sparks, the coil is broken and the windings are grounded out.
Many service manuals advise temporarily replacing a coil that is thought to be bad with one that is known to be good. If the original coil was defective, you will know if the ignition operates properly with the replacement coil. However, it’s usually advisable to obtain a replacement coil. Coil tower spark leaking or a broken tower can occasionally be repaired.
You can come across lock switch extension coils, an early anti-theft technology, when working on older vehicles. In order to prevent “hot wiring of the vehicle,” the low-voltage wire from the ignition switch/battery to the coil was coated in an armored cable. You might be able to locate a swap meet vendor with a coil servicing package for your car if you need factory-style repair of a lock switch extension coil. The instruction manual for them is comprehensive. The lock switch method is often modified by restorers by utilizing a standard coil and running the hot wire through the armored cable.
These types of repairs have easy access to support. Yesteryear () in Port Charlotte, Florida, specializes in these kinds of parts and could be able to help if your automobile has a Delco-Remy coil. You would be wise to seek in the back of hobby periodicals for businesses that specialize in the restoration of lock-switch coils and other ignition parts, advises Randy Rundle, author of Wired for Success.
Every time you work on your own car, there is some risk involved. Prior to doing any repairs or alterations, always get professional advice to prevent damage to you or your vehicle.
John “Gunner Gunnell, a former editor of Old Cars Weekly and Old Cars Price Guide, is the automotive books editor at Krause Publications in Iola, Wisconsin.