Inspect the plugs. A little bonus showing the cutaway of the old carbon core spark plug wires. Spark plug wire replacement tip: To remove spark plug wires from the plug without damaging the boot or wire, use a spark plug boot puller tool instead of a pliers. X Scorch marks signal damage due to high heat from the engine compartment. Attach the spark tester to the distributor end of the coil wire. Please help us continue to provide you with our trusted how-to guides and videos for free by whitelisting wikiHow on your ad blocker. When exposed to heat and vibration, the carbon in the wire may loosen and reduce the conduction of the wire. A) Tech A B) Tech B C) Both Techs A and B ... Tech A says that you can test for defective ignition wires by using a spray bottle and water. How to Test for an Engine Misfire With a Spray Bottle of Water. Have someone else rev the engine while you continue to look at it. A normal spark plug will appear dry with a grayish color. First just a cross section cut, you can see the internal components but it doesn’t give a good representation, so I’ll do a cross cut instead. This unit runs inline with many spark plug wires and/or coils and gives you a window to see active spark. Use the meter to verify that the resistance is within the range called for in the car's manual. "I'm no mechanic, but I have tools and try to learn as much as I can. Next, remove one of the spark plugs' wires from the plug itself. Usually, these wires run from the distributor cap to each of the spark plugs individually. Editor's Pick: ACDelco. Approximately 5 ohms per foot. Bend the wires gently to visually check that no cracks appear. Leave the door partly open and the vehicle's exhaust pipe pointing outside. Step 3. Be sure to note which spark plug your engine requires–PartsVu recommends NGK. This article has been viewed 410,688 times. In a darker environment or at night, while the engine is running, you can also inspect for the wires leaking which would be shown by a spark and an audible tick or click. Can damaged spark plug wires cause a car to jerk at low speeds? Step 2: Remove the spark plug using a spark plug socket. About: Car enthusiast YouTuber creating helpful tutorial videos on both repairs and customizations. These will be a line of wires coming out of the cylinder head and attached at the other end to the distributor or ignition coils. Step 1: Disconnect the spark plug lead.Then, clean the area around the spark plug to avoid getting debris in the combustion chamber when you remove the plug. What would the resistance be on 2 feet in ohms? Make sure it matches the resistance in the manual. If carbon tracking is present, the spark plug and the wire should be replaced. How do I change spark plug wires on a Chevy 2.2 engine? Some manufacturers do this to cancel out magnetic fields. Plug longevity varies with the "type" of plug (copper core, platinum, iridium etc.). Touch the test probes together to determine the existing resistance in the test leads, then hold one test probe on one terminal, the other probe on the other terminal, this wire show’s 10,000 ohms, which by generic specs is good. Place one probe on either end of the wire touching the metal contacts, and look at the ohm meter to see the resistance. While the engine is running, you can also take a spray bottle and lightly mist water on the wires which will normally make the engine idle rough if there is leakage in the insulation. If it comes off easily, replace it. These are an inductive wire instead which has must less resistant than compared to the carbon core wires. Spark plugs are the smallest component of your car that has the biggest effect on how well your engine will run. Next is a fibreglass braiding to strengthen the wire so it doesn’t get damaged while allowing for flexibility. 1. This article was co-authored by Mike Parra. Step 1. Over time spark plug wires will wear out, causing various engine operation issues such as hard starting, misfires, rough idling, poor performance, poor fuel economy, and improper combustion burn. I would. Step 2 - Check for Looseness. You can actually see the black residue on my finger is carbon. Any electrical hiccup under the hood can cause one of … Even if the plug wires meet within their specifications, it doesn’t necessarily mean they are still in good condition as the insulation could be failing, terminals are corroded, or perhaps the conductor inside is broken and that would be show up if you were bending the wire while testing it creating and open circuit. The spark plug wire has a seemingly simple job: Carry the high-voltage electricity produced by the ignition coil to the terminal of the spark plug. Set the ohmmeter to the appropriate scale and measure the wire. % of people told us that this article helped them. If you did not see a spark, remove the coil wire from the distributor cap. You can measure the resistance of the spark plug wires with a digital multimeter to see if they are working properly. If the loss of contribution moves with the coil, the ignition coil is faulty. Setting the multimeter to the ohms sitting to measure resistance, on the 20k setting which will show us values in the 10,000 range. Thank you.". Examine the wiring of the plugs. My car is misfiring and the hold light is flashing in my 2005 Chevy Aveo. And finally the carbon impregnated fibreglass core, where the electricity flows. What can I do? This locking tab is the one that makes sure the connector does not become un-plugged from the ignition coil. To verify whether the coil is to blame, you’ll want to swap the coil to another cylinder and repeat the power balance test. This wire is about 2 feet long so we should be expecting about 1300 to 2500 ohms. Did you make this project? This article has been viewed 410,688 times. Yes, although that can be caused by a variety of problems. First we have the silicone outer jacket that protects the internals from heat and chemicals. ACDelco offers a variety of spark plug wire sets for a wide range of applications and vehicles. ", https://www.popularmechanics.com/cars/how-to/a82/1272351/, https://www.yourmechanic.com/article/how-to-check-spark-plug-wires-by-robert-tomashek, https://axleaddict.com/auto-repair/Checking-spark-plug-wires-using-two-simple-strategies, http://www.zr1specialist.com/HAT%20Web/facts%20and%20failures/spark%20plug%20carbon%20track.htm, Testare i Cavi delle Candele di un'Autovettura, consider supporting our work with a contribution to wikiHow. It’s not expensive and it ensures that that part of the car is good to go. Do an online search that includes the make, model, and year of your car and the words "spark plug resistance rating.". If you don't, you run the risk of shocking yourself. Damaged clips may allow the wires to slip and not hold their proper position. Spark plug wires with bad insulation affect engine performance, especially during damp weather on rainy days. right path. He is ASE (Automotive Service Excellence) certified, has an AA degree in Automotive Repair Technology, and has over 20 years of mechanic experience. Thanks to all authors for creating a page that has been read 410,688 times. We know ads can be annoying, but they’re what allow us to make all of wikiHow available for free. Do not assume that crossing spark plug wires is a bad sign. A fouled spark plug occurs when the plug isn’t burning fuel normally, leaving damage to the plug which can cause the engine not to start. We use cookies to make wikiHow great. We are looking at 940 ohms. Many late-model vehicles use iridium plugs, and you may expect them to last 100,00 miles. Your Engine Got Wet Where It Didn't Like It. Look in the owner's manual to find the appropriate resistance for the wires. This article was co-authored by Mike Parra. Research source. Caution: Never perform a power balance test by disconnecting the spark plug wires. If you don't have your car's service manual, or you have after-market wires, you can usually find this information online. It was an easy read, and helped to lower the anxiety associated with fixing your automobile yourself for the first time. Step 4. ; Step 3- Inspect the spark plug for very stubborn deposits, or for cracked porcelain or electrodes that have been burned away.If any of these conditions exists, replace the spark plug. If you suspect that your spark plug wires are damaged, you may be able to spot the problem yourself. Spark plug wires deliver high voltage to the spark plugs, which then ignite the air-fuel mixture in the engine’s cylinders. It carries the high voltage (30k to 50k volts) produced by the ignition coil to the spark plug. Test the wire from end to end with the leads of the meter. A spark plug wire is a basic but critical engine component. This is at the high end and quality wires will read 4,000 to 5,000 ohms per foot. For the domestic wire a good reading is no greater than 12,000 ohms per foot. Since you're replacing those old, worn-out spark plugs, it's a good idea to replace … References. Step 2. The simple way I always check spark plug wires is to take a screwdriver with a good plastic handle and put an aligator clip lead on it with the other end of the wire grounded. Overheated – insulator of the spark plug is pure white, and top of the spark plug is degraded. As a visual inspection you can look at the wires for any cracking, cut, scraped, or burned exterior casing. Bend and check the wires for brittleness and cracks. Run a damp rag from end to end and feel for any break. Reply For copper core wires, the resistance will be 1 to 6500 ohms, inductive wires the resistance will be 2200 to 8000 ohms per 1 meter or 650 to 2500 ohms per foot and carbon wires, the resistance is 10000 to 23000 ohms per 1 meter or 3000 to 7000 ohms per foot. If you really can’t stand to see another ad again, then please consider supporting our work with a contribution to wikiHow. Step 2- Remove the spark plug using a spark plug socket. Testing Spark Plug Wires. Remove one spark plug wire from its plug. The insulation (rubber coating outside the wire) may break and cause arcing. With the engine running, spray the spark plug wires with water. Remove the spark plug wire. Spark plug wires. But, you also have to know how to put spark plug wires in the correct order. Do I need to change the wires when I change the plugs? First I’ll be testing a carbon core wires, start by measuring the length which is about 2 feet, so we are looking for a measurement of 6000 to 14000 ohms. Anti-freeze or engine oil leaking into the spark plug tube and drowning the spark plug and spark plug boot. The ignition coil's connector's locking tab has broken (see the photo in the image viewer, the arrow points to it). Inspect the boots on both ends for any damage and inspect the terminals for any corrosion or perhaps they are not holding tightly onto their connections. Stay up to date with my latest tutorials, don't forget to FOLLOW my profile and be sure to check out my YOUTUBE page as well for all your DIY needs. Inspecting the Spark Plug Wires with the Engine Off, {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/c\/c6\/Test-Spark-Plug-Wires-Step-4-Version-3.jpg\/v4-460px-Test-Spark-Plug-Wires-Step-4-Version-3.jpg","bigUrl":"\/images\/thumb\/c\/c6\/Test-Spark-Plug-Wires-Step-4-Version-3.jpg\/aid1405831-v4-728px-Test-Spark-Plug-Wires-Step-4-Version-3.jpg","smallWidth":460,"smallHeight":259,"bigWidth":"728","bigHeight":"410","licensing":"