My Engine Has No Spark at the Coil

Updated on December 18, 2019
Dan Ferrell profile image

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

Worn out spark plugs will fail to ignite and start your engine.
Worn out spark plugs will fail to ignite and start your engine. | Source

An engine with no spark produces a no-start condition. The problem may come from:

  • worn out plugs
  • fouled plugs
  • bad ignition coil
  • faulty distributor
  • bad rotor
  • bad ignition module

The following sections show you how to diagnose a distributor and a electronic ignition system with no spark.

Since both systems may change from one model to the next, it's recommended to have the vehicle repair manual for your particular model when diagnosing the system.

Index
1. Troubleshooting the Ignition System
2. Diagnosing a Distributor Ignition (DI) System
3. VIDEO: Using an Adjustable Ignition Spark Tester
4. Diagnosing an Electronic Ignition (EI) System
5. Diagnosing a No-Start Condition

1. Troubleshooting the Ignition System

When diagnosing a faulty ignition system, don’t forget about obvious problems. For example, you may be dealing with:

  • worn spark plugs
  • worn or bad spark plug wires
  • worn or bad distributor cap
  • worn or bad rotor

This may depend on your particular model. Consult your vehicle repair manual or owner’s manual for ignition system components maintenance intervals. Sometimes, servicing the system may solve the problem.

After servicing the system, even if the problem continues, at least you know you are working with components in good condition.

In general, you’ll be dealing with one of two types of ignition systems:

  • Old models with a distributor system
  • Modern engines with electronic ignition system (no distributor)

Within each of these two different systems, you’ll find many variations and configurations. So it’s a good idea to have the vehicle repair manual for your specific model when doing your diagnostic tests.

Regardless of your particular system, remember that in a no-spark problem, you are focusing on common components to all cylinders in the system. This may include an ignition coil, distributor cap, rotor, crankshaft and camshaft sensors, and modules, depending on your particular model and system configuration.

If you don’t have the repair manual yet, you can get a relatively inexpensive copy from Amazon. Haynes manuals come with many maintenance, troubleshooting and replacement components projects that you can do at home using mostly common tools.

Using a Spark Tester

Use the correct spark tester for your system. You’ll need either a low-voltage or high-voltage tester. If possible, get an adjustable spark tester that you can manually set to your ignition system voltage rating. Consult the repair manual for your ignition system specifications.

A faulty rotor or distributor cap can prevent spark ignition.
A faulty rotor or distributor cap can prevent spark ignition. | Source

2. Diagnosing a Distributor Ignition (DI) System

Some distributor ignition systems include electronic components used to control spark timing. Different configurations exist, so you may need to refer to the service manual for your particular vehicle model when diagnosing the system.

During your diagnostic, you may need to include all the components of the primary circuit, and the secondary circuit up to the distributor’s rotor.

Basic Testing Procedure:

  1. Apply the parking brakes.
  2. Set the transmission to Neutral (manual) or Park (automatic).
  3. Disconnect a spark plug wire from the spark plug. Pull the wire at the boot to prevent damage to the wire. You can use a set of wire removal pliers, if the boot is hard to reach.
  4. Connect a spark tester to the spark plug wire. You can use an adjustable spark tester you can manually set up for the appropriate voltage range for your particular system.
  5. Attach the spark tester to engine ground. You can use a non-painted bracket or bolt on the engine to secure the tester. Using a spark tester instead of a screwdriver is better, if you haven’t done this type of test before, to protect yourself from ignition system high voltages.
  6. Stand to one side of your car and ask an assistant to crank the engine only for a few seconds to avoid much fuel going to the catalytic converter and cause damage.
  7. While the engine cranks, you should see a bright, blue spark at the tip of the spark tester. If there’s a good spark, including the rest of the cylinders, the ignition system is working properly. If only one or a few cylinders have a weak or no spark, the problem is in the secondary side of the system. Check for worn or damaged spark plug wires, worn or faulty distributor cap. Consult your vehicle repair manual, if necessary.

The following video shows you how to test ignition spark using an adjustable tester.

When all cylinders register a weak or no spark and the wires are new or in good condition, there’s a problem in the system. Continue with the following steps.

3. Using an Adjustable Ignition Spark Tester

Test the ignition coil positive and negative side.
Test the ignition coil positive and negative side. | Source

Checking for spark at the ignition coil:

  1. Check for voltage output at the ignition coil. Disconnect the ignition coil wire from the distributor and install the spark tester to the wire and ground the tester to the engine.
  2. Crank the engine for a few seconds. If there’s spark, the problem is with the distributor cap or rotor. Consult your vehicle repair manual, if necessary. If there’s no spark or the spark is weak, check the resistance of the wire that connects the ignition coil to the distributor cap. Consult the wire resistance specifications in your repair manual. If resistance is within specifications, continue with the next steps; otherwise, replace the wire and test for spark again.
  3. Connect a test light or digital multimeter (DMM) between the negative side of the coil and ground. Refer to the next drawing or consult your vehicle repair manual, if necessary.

Two types of ignition coils are shown in this picture as a reference.
Two types of ignition coils are shown in this picture as a reference. | Source
  1. Turn the ignition switch to On or Run. If the testlight stays off or the DMM doesn’t register any voltage, either the coil’s primary winding has an open or the circuit between the ignition switch and the coil’s battery terminal has an open. Consult your repair manual.
  2. Leave the test light or DMM connected and crank the engine for a few seconds. If the test light flashes or the DMM registers voltage, the problem is a faulty ignition coil. If the test light doesn’t flash or the DMM doesn’t register voltage, continue to the next step.

Two types of coils are shown in this drawing as reference.
Two types of coils are shown in this drawing as reference. | Source
  1. Test for voltage from the ignition switch at the positive side of the coil. Refer to the above image. If there’s no voltage, check the wire between the ignition switch and the coil and, if necessary, the switch itself. If there’s voltage, the problem may be with the pickup unit. If the pickup is good, then the problem may be with the ignition control module.

Consult your vehicle repair manual to test the pickup unit and ignition control module, if necessary. Also, if your model has a CKP sensor, check the connection, connector and the sensor itself.

Worn spark plugs, and faulty ignition module and sensors can interfere with the ignition system in an Electronic Fuel Injection system.
Worn spark plugs, and faulty ignition module and sensors can interfere with the ignition system in an Electronic Fuel Injection system. | Source

4. Diagnosing an Electronic Ignition (EI) System

EI systems come under different configurations. You particular model may have components not found in other similar systems. The following is a general diagnostic procedure. You should consult the vehicle repair for your particular model.

Your EI system has a CKP and, depending on your particular model, there could be none, one, or two CMP sensors.

The CKP tracks crankshaft position and engine speed, while the CMP tracks cylinder identification and camshaft position in relation to crankshaft position. Both are an important part of the ignition system, so make sure to include them in your diagnostic procedures.

On some models, the computer sets a diagnostic trouble code (DTC) when a fault is detected in the ignition system, CKP or CMP sensor. So make sure to scan your car’s computer for potential codes, even if the check engine light is not on. A pending or hard code can point you to a system or sensor you need to test.

Before you start doing any tests, visually inspect all the ignition wires and connections, including those for the CKP and camshaft position (CMP) sensors. Make sure they all are clean and tight.

Basic testing procedure:

  1. Set the emergency brakes.
  2. Set the transmission to Neutral (manual) or Park (automatic).
  3. Disconnect a spark plug wire or coil-on-plug from a spark plug. When disconnecting, pull the wire at the boot to prevent damage to the wire. You can use a set of wire removal pliers, if the boot is hard to reach.
  4. Connect a spark tester to the spark plug wire or coil’s boot.
  5. Attach the spark tester to engine ground. You can use a non-painted bracket or bolt on the engine to secure the tester. Using a spark tester instead of a screwdriver is better, if you haven’t done this type of test before, to protect yourself from ignition system high voltages.
  6. Stand to one side of your car and ask an assistant to crank the engine only for a few seconds to avoid much fuel going to the catalytic converter and cause damage.
  7. While the engine cranks: If you see a bright, blue spark, the ignition system is working properly. If you don’t see any spark or the spark is too weak, check the crankshaft position sensor and camshaft position sensor(s) as necessary. Then continue with the next steps.
  8. Visually check the wiring between the car’s computer and the ignition module. Check for signs of damage. Then use a digital voltmeter to make sure the power and ground circuits to the computer are OK. Consult the diagram for your particular model to access and identify the wires.
  9. Check the battery terminal for the coil pack by connecting a DMM between the terminal and ground. Turn on the ignition switch. If you don’t get battery voltage at the terminal, check that part of the circuit using your repair manual. If the coil’s power feed has the correct voltage, check the circuit’s voltage drop for the circuit and components, searching for an electrical open or high resistance. This other post on automotive voltage drop testing can give you an idea of this test procedure. Also, consult your vehicle repair manual, if necessary.

Continue with your tests as described in your vehicle repair manual, if necessary.

Diagnosing a faulty ignition system is a straightforward procedure sometimes.
Diagnosing a faulty ignition system is a straightforward procedure sometimes. | Source

5. Diagnosing a No-Start Condition

In most cases, diagnosing a no-spark problem is a straightforward procedure. However, the problem might not be in the ignition system itself, but a sensor the computer depends on for ignition system operation. For example:

This depends on your particular model. Consult your repair manual.

However, if there’s spark and the engine cranks but doesn’t start, check for:

  • Battery voltage and condition
  • Fuel system pressure
  • Good engine grounds
  • Vacuum leaks
  • Broken timing belt or loose timing chain
  • Low compression

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Questions & Answers

    © 2019 Dan Ferrell

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        2 months ago

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