There is more to consider though. At its basic level, the spark plug wire exists solely to transmit electricity from the coil or distributor to the spark plug. The purpose of the resistance in the plug wires is there so that the (1) plug firing voltage is great enough to maintain a sufficent spark firing time and (2) the resistance suppresses interferance with electronic equipment and radios. S ... Wire 1: 4.8k Ohms Wire 2: 5.5k Ohms Wire 3: 5.5K Ohms Wire 4: 6.2K Ohms Now, wires 1-2 are the same length, as are 3 and 4. An Ohm meter, which is part of a multimeter, can only check a spark plug for a short circuit or a breakdown of insulation resistance. A Taylor ThunderVolt plug wire could easily test at around 40 ohms per foot, which means reduced-resistance and more energy applied to the spark plug. High-temperature-rated boots might be required if you have headers or other routing that puts the sensitive wires near a strong heat source—mainly the exhaust. The resistance of many wires is measured in ohms per foot. That pinging noise is the radio-frequency interference from an uninsulated plug wire. To perform a wire resistance test, connect an ohmmeter across each end of the wire. Those resistance numbers are fine. For stock applications, an OEM-spec wire might be best despite it having greater resistance than an aftermarket wire. Testing a spark plug wire's ohm resistance will display how much resistance there is to the current that passes through the wire. The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. Re: Spark Plug Wire Resistance reading I don't know personally, but zero"ish" for stranded wire and 5k ohms"ish" for resistance wire, obviously length dependent. Typically resistance should NOT be over 5,000 ohms per inch or 100.000 ohms total. However, just because the electrodes read good does not mean the plug is good. NGK plugs are 5k ohms, they made that easy to find. That is a tough balance to strike on modern computer-heavy cars, or even racers with sensitive data logging equipment. The best spend of your money is to buy a wire that protects against just enough interference to keep the rest of your car functioning properly—but no more. Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. Not only did insulation join the features list for plug wires, increasing use of electronics as the decades wore on required the development of EMI and RFI suppression. New Tempest (formerly Unison-Autolite) will measure 1000 OHMS. If the meter reading is anything other than what you saw in Step 4, the plug is bad. Any clue why the old wires are so much different. Headers are notorious for causing problems, so invest in some extra insulation to prevent your new wires from literally melting down. But once the plug’s resistance value exceeds 5000 ohms, the plug should be replaced. maximum resistance value of any aviation spark plug is 5,000 ohms. A wire with high resistance can be in the 5000 ohms per foot range for especially high-output ignition systems, whereas a low resistance performance wire could easily get double digit ohms per foot. The most common instance of radio frequency is the phenomenon that occurs when a home mechanic replaces the plug wires on a vintage car and afterwards the radio has a pinging noise whenever the driver turns on sweet tunes while the engine is running. Simply attach or hold a meter probe on each end of the cable and read the total resistance on the meter. Copyright 2020 Leaf Group Ltd. / Leaf Group Media. The key indicator is the suddenness of the drop..." I ohm-test … There wasn’t even insulation. ianwayne. It could have the tip missing or any of several other problems. One reason is becasue many OEM wires utilize carbon fibers as the conductive medium inside the insulated covering. Plug wires of larger diameter could simply have larger conductors inside the wires, but their size could also be due to other features. Touch the test leads together. Make sure it … Those are the four things a gasoline-fuel engine needs to run properly. Jump to Latest Follow 1 - 7 of 7 Posts. So the Ohm meter test can show if the plug has a short or resistance, but it can't prove that the plug is good in all respects. The true ignition coil primary resistance value is 0.6 ohms, (0.8 – 0.2 = 0.6). Keep in mind these are generic values and may vary between vehicle manufacturers and spark plug wire manufacturers. If you have any additional tips, be sure to leave them in the comments below. Like everything in life that is good, that insulation has side effects. Spark plug wire resistance Q. As an example, if you have 4-feet of Super Stock 5000 or Street Fire wire, you should have an ohm reading of 2,000 ohms. OEM spark plug wires can generally have a resistance of 10kOhm/ft to 15kOohm/ft. Look in the owner's manual to find the appropriate resistance for the wires. Note the reading. they look the same, heavy duty with the braided ground wires. Tools Needed: Digital multimeter Use the digital multimeter, set to Ohms Ω. Most domestic vehicles use spark plug wires with a fiber glass core covered in latex graphite, which provides between 10,000 and 12,000 ohms of resistance per foot of wire. Also, all the shielding inside a wire is not free. When one cylinder's spark plug has a resistance value of 4300, and another cylinder's plug having a resistance of 5400, would you think that it really matters? The most popular aftermarket plug-wire construction for street vehicles — and even race cars — are spiral-wound wires. the old plug wires measure 1000 ohms,, the new wires measure 4000 ohms. Then, pull the boot off of the spark plug and unscrew one of the wires at the end. Now the market is flooded with options when it comes to plug wires. That said, I'm not really trying to prove much of a point, I'm just sharing some information. Press the points of the meter leads firmly to the metal to ensure a good connection. If you have stranded wire and cut into it you will have stranded metallic wire. Try 'blipping' the throttle, pressing the throttle to raise … Spark plug wires can easily be visually inspected for tears, burns or black spots that may pinpoint a voltage leak. Larry : Wrong about what? Those larger wires typically have a lower resistance per foot—and this, not size, is the key thing to pay attention to. It’s not a difficult process; it just takes a bit of patience and attention to detail—like any other automotive project. My Profile My Preferences My Mates. Here is the first: 200 (ohm) 2K (2,000 ohm) 20K (20,000 ohm) 200K (200,000 ohm) 2M (2,000,000 ohm) 20M (20,000,000 ohm) 5.5 on a 20k or 200k scale is 5.5k ohms If you're reading something that is very low resistance, like a light bulb or a piece of wire, select the lowest (200 ohm). The lower the number, the lower the resistance, which means that more current will reach the spark plug. The carbon fibers produce minimal RF noise, however they have high resistance. Understanding your meter readings . Take a reading in kilohms (1 kilohm=1,000 ohms). Sign up for the latest automotive news and videos—in short, everything for people who love cars. The Society of Automotive Engineers suggests the maximum resistance should be 12,000 ohms-per-foot. A wire with high resistance can be in the 5000 ohms per foot range for especially high-output ignition systems, whereas a low resistance performance wire could easily get double digit ohms per foot. If we divide 2,000 by 2 — we get 1,000 ohms of resistance per foot. It could have the tip missing or any of several other problems. A typical bad plug will cause an immediate drop of 250 or more RPM, at the mag check. Spark plug resistance. According to the first link, from Popular Mechanics, spark plug wires are supposed to have 10,000 to 15,000 ohms per foot. A spark plug bomb tester can test a bad plug and lead you to conclude it is serviceable. The resistance of many wires is measured in ohms per foot. Usually its not increased resistance that causes you to buy spark plug wires, it's the degradation of the outer material, causing interference issues. Close inspection of the boots and terminals should also be checked. Reply Reply Author. A meter value with a “k” following the number will require a conversion to a whole number. NGK resistor covers feature a resistor element constructed of high quality ceramic material, designed long enough to prevent interior flashover, and yet maintain constant resistance, with only slight variation under over-load conditions. Your reading could include your body resistance and falsely indicate a bad plug. Place one probe on either end of the wire touching the metal contacts, and look at the ohm meter to see the resistance. For new plugs, we recommend 4000 ohms as the maximum acceptable value. The meter should read zero Ohms. Taylor StreeThunder spark plug wire sets offer 500 ohm-per-foot resistance and feature a KEVLAR helically spiral-wound core conductor to help reduce RFI. Ignition systems which use a magneto are often best served by the lowest resistance wire possible. On two wheels Motorcycle racing //TekniWiki; NGK Resistor Caps . These Granatelli Motor Sports spark plug wire sets combine a solid core, which exhibits nearly zero ohms of resistance, with a … Comparably, MSD’s Street Fire wires give users a spark-friendly 500 ohms/ft of resistance. Testing Plug Wires: If you have access to a factory service manual for your car, you may find a resistance rating for the spark plug wires, (such as 1000 - 4000 ohms per foot). What's New 3 12 24 72. The OHM Meter check is simple, readily available, and amazingly accurate in finding misfiring plugs. Lower resistance means more of the ignition coils energy is going towards bridging the gap or the spark plug. Search My Stuff. Move the test leads apart. The meter will read internal wire resistance in ohms. Higher readings indicate too much resistance, possibly because of rusting or faults in the wire. We’re here to help you make sense of the features and technology out there. A new Champion plug will have a value of 800 to 1200 OHMS. 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. A SPARK PLUG WIRE RESISTANCE TEST will check the spark plug conductor or coil wire conductor. I suppose they could be the wrong ones? I keep finding Champion resistor plugs at 80k ohms. Over the years the demands on these humble wires have increased, and thus the technology wrapped into them has also advanced. Any resistance at all would mean the plug is bad. Types Of Spark Plug Wires. I saw one little statement in an aviation forum that they use some sort of silicon carbide voltage dependent resistor and can't be … Look at the connectors, check for corrosion. You can also measure the resistance of each spark plug wire, but like coils, values may vary between wire brands. Yet again, not quite. Discussion. This test cannot be done with the spark plug wire attached. That hotter spark can create a … So if a little insulation is great, more must be better, right? Most resistor spark plugs use a monolithic resistor, generally made of graphite and glass materials, to filter the electrical voltage as it passes through the center electrode. While it sounds pretty simple, the reality is that even vintage engines are quite picky about how each of these four items is attained. Electromagnetic and radio-frequency interference can be a real pain in the butt. Touch one meter lead to the terminal of the spark plug and the other lead to engine ground. A good spark plug should show an open circuit between the center electrode and the tip. For the sake of argument though, maybe someone has a set of Bosch or NGK platinum plugs they could test? The automobile had been around for at least 50 years when my 1930 Ford Model A was built, and guess what, it’s plug wires are just straps of metal from the distributor to the plugs. Not hard to differentiate between the two. According to the second link, from David Kucharczyk, silicon wires … Fuel, air, compression, and spark. Replace any plug above 5000 OHMS. A good spark plug should show an open circuit between the center electrode and the tip. Original … After founding a small telecommunications engineering corporation and visiting 37 countries, Asmus studied broadcasting at Arizona State University and earned his Master of Fine Arts at Brooklyn College in New York. Installing new plug wires is a part of most basic tune-up to-do lists, and if your favorite cars wires haven’t been changed in a decade or so it might be time for you to start shopping. Found these 2 explanations in other forums about Spark Plug Wire Resistance and Ohms. Now, onto testing the wires. To help assure reliable and trouble free operations, Tempest recommends replacing spark plugs in service having a resistance value of more than 5000 ohms (5k ohms) or less than 500 (0.5k ohms). Spark plug resistance . If a spark plug falls off a workbench or … Find Spark Plug Wire Sets 0 ohms/ft. NGK Spark Plugs for formula one racing quality. any ideas?..oh won't the new wires with more resistance lower the voltage to the plug, which may result in a weaker spark? The spark needs of a stock 216-cubic-inch inline-six Chevrolet are drastically different than those of a supercharged big-block Ford. As the plug ages, values below 5000 ohms are acceptable. The higher voltage of a coil on plug or distributor system can create enough voltage that a slightly higher resistance wire will not greatly affect spark strength, but the relatively lower output of a magneto means using a lower resistance wire is more important to ensure a hot spark from the spark plug. Set your multimeter to the "Ohms" position. Either you will be at one extreme or the other. Lower resistance means more of the ignition coils energy is going towards bridging the gap or the spark plug. A winning spark Racing Spark Plugs. Champion seems to think tattoos are more important than their specifications or getting through their web site. The spark plug is fouled and shorted to ground or is open and the magneto, which is functioning normally, is unable to fire it. There is often the option to purchase pre-terminated wires, where the wires have been cut to the proper length for your application, but if you have something custom or want a cleaner appearance than factory, building your own spark plug wires might be the way to go. It is for this reason that most racing plugs are non-resistor types. Whether you are using an auto ranging meter or a manual adjustment meter for testing, the reading may appear similar to this; (example: .826 k). Do not touch the tips of the test leads or the vehicle ground. Connect test leads to the multimeter by plugging them into the jacks. The lower the resistance, the better quality conductor materials are used in making the spark plug wires. That electrical noise can wreak havoc on everything from AM radios to engine and transmission control computers. If all your spark plugs test as good with the Ohm meter, you should find a more thorough way to test them. An Ohm meter, which is part of a multimeter, can only check a spark plug for a short circuit or a breakdown of insulation resistance. Champion Resistor Spark Plug Resistance ? Bet if you measure the resistance of your spark plug wires you will find that they are much higher than the spark plugs are, plus the logner wires will have more resistance than the short ones do. This is because your "wires" aren't really wires at all but conductive plastic or fiber. This value was simply published by the marketing company to suit their marketing and advertising needs. The side effects are resistance and cost. The meter should read infinite. Once you have your wire chosen, you’ll need to connection the distributor cap (or coil, for coil on plug applications) and the spark plugs. A broken wire allows no electricity reading at all, which will cause the multimeter to register resistance as \"over limit.\" Remove the ignition wire from the spark plug. If it falls within the manufacturer's measurement range in your repair manual, the plug wire is not your problem. If you know how to use an ohm meter, you can measure the plug wires resistance from end to end and see if they are within specifications. When spark plugs are new, the resistance value is between 500 and 3000 ohms. 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Any resistance at all would mean the plug is bad. The EMI and RFI suppression keeps the electrical noise of the ignition charge moving within the wire to a minimum. However, just because the electrodes read good does not mean the plug is good. On the other hand, many import models like Nissan, Honda, and Toyota use spiral-wound stainless steel mag wires with approximately 500 ohms of resistance per foot of wire. Plug wires are often advertised by the diameter of the wire, making it easy to look at the options for plug wires and immediately think if 7mm is good, 8.8mm must be great. Spark plug wires are easily broken internally when being removed from the plug, as they can become attached to the spark plug. So the Ohm meter test can show if the plug has a short or resistance, … That hotter spark can create a more even burn of the fuel/air mixture in the cylinder, and thus, more power output from the engine. Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. Those simple conductors evolved to require insulation to shield the ever-increasing voltage from jumping to an unintended ground rather than through the spark plug. Replace the wires if you feel like it, but it's not necessary. Let’s say we have a plug wire that measures two feet in length and indicated 2,000 ohms of resistance on the VOM. Early spark plug wires were very simple—just metal that conducted. Spark Plug Wire Resistance and get Free Shipping on Orders Over $99 at Summit Racing! That’s what a spark plug wire is—a conductor.