QA

How To Check Spark Plug Wires With A Multimeter

Can you test spark plug wires with multimeter?

Use a digital or analogue multimeter (or ohmmeter) to check if the resistance of each spark plug wire is within the manufacturers’ guidelines. To do this, set the multimeter to the appropriate scale and measure the wire by placing the probes on each end of the wire lead, making sure they touch the metal contacts.

How many ohms should a good spark plug wire have?

The Society of Automotive Engineers suggests the maximum resistance should be 12,000 ohms-per-foot.

How do you fix arcing spark plug wires?

The techniques to stop spark plug wires arcing Routine check-up of the engine and the wires as well. Replace all the spark plug wires with the new wires. Replace the arcing ignition coils. Determining the disconnected shift linkage and fix them.

What’s better 7mm or 8mm spark plug wires?

8mm spark plug wires are a heavier gage wire than the 7mm type. A more robust core provides a lower resistance path for the power, thereby allowing more power to reach the spark plugs. Additionally, the 8mm wires have a thicker outer coating that keeps the core safe from damage.

Does resistance matter in spark plug wires?

Resistance is the biggest buzzword when it comes to spark plug wires, but it usually comes at the cost of EMI and RFI suppression. And despite all the hoopla surrounding resistance, it will not typically make any difference in horsepower in an otherwise healthy and properly functioning motor.

How do you check spark plugs without removing them?

Test the spark plug ignition by disconnecting the spark plug wire from the spark plug. Hold the end of the spark plug wire close to a metal surface. If the spark plug is good, you will see a spark or you’ll hear a crackling noise. This means that voltage is getting through the wire to the spark plug.

What would cause a spark plug not to fire?

A spark plug won’t fire properly if its electrodes have been worn thin, if they are covered with combustion deposits or if they’re wet. If the plug has seen many hours of service, the electrodes may just be worn out, and replacing the plug will restore normal engine operation.

Can touching spark plug wires cause misfire?

As long as the spark plugs and wires are good not a problem for the wires to touch. They don’t fire at the same time and the distance between wires is always more than the spark plug gap.

How do you identify arcing?

If you hear any popping, buzzing or hissing sounds from electrical connections, those are signs of arcing. The best way to protect your property is to get an arc-fault interrupter (AFCI) installed; these devices are able to detect arcing faults and protect the system from their effects.

What would cause a coil to arc?

The single ignition coil, or coil pack on newer models, sends a high voltage spark to the plugs to ignite the combustion gases in the engine cylinder. Coil case leaks result in arcing, where the spark (voltage) escapes to an outside source and grounds against its surface.

How do you test a spark plug wire with a screwdriver?

Use a screwdriver to test the insulation of the wires. Tie the other end of the wire to the ground source Then drag the screwdriver tip down the length of each spark plug wire, around the coil, and the boots. If you see an arc from a wire to the screwdriver, you have defective wire.

Are bigger spark plug wires better?

That thicker wire core provides a lower operating resistance, allowing more spark energy at the spark plug. If the plug wire’s resistance is too high, the spark energy to the spark plug will decrease, causing poor performance and potential spark plug fouling.

What does the MM mean on spark plug wires?

A: The 8mm is sufficient for most street applications. Our ThunderVolt 50 10.4mm wire is especially recommended in high-boost/extreme-cylinder-pressure applications but will work fine on any engine. The thicker wire diameter provides a wider margin of safety to prevent voltage leaks.

What is the best core material for spark plug wires?

The majority of spark plugs feature a copper-core center electrode. Copper is an excellent conductor of electricity – better than any other type of material used in spark plugs – and also transfers heat faster.

How do I know if my spark plug is lean or rich?

Good running conditions: If everything is good, the spark plug should have a tan/light brown color. Rich running conditions: If your engine is running too rich, the spark plug will be black and sooty. Lean running conditions: If your engine is running too lean, the spark plug will be white.

What can damage spark plugs?

Causes of a carbon-fouled spark plug include a dirty air filter, excessive driving at low speeds, too rich of a fuel/air mixture, dirty fuel injectors or idling your vehicle for too long.

Why is my coil not getting power?

If this wire has no power, then your ignition coil is not receiving current. You should check the wiring from your ignition switch to the coil for breaks in the wire and repair them. If this wire has power, then the wiring from the ignition switch to the coil is working properly and you can move on.