What's New 3 12 24 72. Fuel, air, compression, and spark. Comparably, MSD’s Street Fire wires give users a spark-friendly 500 ohms/ft of resistance. The Society of Automotive Engineers suggests the maximum resistance should be 12,000 ohms-per-foot. Remove the ignition wire from the spark plug. Then, pull the boot off of the spark plug and unscrew one of the wires at the end. Spark plug resistance. One reason is becasue many OEM wires utilize carbon fibers as the conductive medium inside the insulated covering. The resistance of many wires is measured in ohms per foot. 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? That’s what a spark plug wire is—a conductor. Plug wires of larger diameter could simply have larger conductors inside the wires, but their size could also be due to other features. 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). 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 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. 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. any ideas?..oh won't the new wires with more resistance lower the voltage to the plug, which may result in a weaker spark? 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). Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. A typical bad plug will cause an immediate drop of 250 or more RPM, at the mag check. 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. We’re here to help you make sense of the features and technology out there. 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. If all your spark plugs test as good with the Ohm meter, you should find a more thorough way to test them. 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). Your reading could include your body resistance and falsely indicate a bad plug. So if a little insulation is great, more must be better, right? That said, I'm not really trying to prove much of a point, I'm just sharing some information. I keep finding Champion resistor plugs at 80k ohms. Look at the connectors, check for corrosion. Yet again, not quite. Connect test leads to the multimeter by plugging them into the jacks. 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. Spark plug resistance . Richard Asmus was a writer and producer of television commercials in Phoenix, Arizona, and now is retired in Peru. Find Spark Plug Wire Sets 0 ohms/ft. Typically resistance should NOT be over 5,000 ohms per inch or 100.000 ohms total. 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. Discussion. That electrical noise can wreak havoc on everything from AM radios to engine and transmission control computers. Those resistance numbers are fine. A good spark plug should show an open circuit between the center electrode and the tip. 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. 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. That hotter spark can create a … Take a reading in kilohms (1 kilohm=1,000 ohms). 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. The lower the number, the lower the resistance, which means that more current will reach the spark plug. Search My Stuff. According to the second link, from David Kucharczyk, silicon wires … If a spark plug falls off a workbench or … This is because your "wires" aren't really wires at all but conductive plastic or fiber. The spark needs of a stock 216-cubic-inch inline-six Chevrolet are drastically different than those of a supercharged big-block Ford. However, just because the electrodes read good does not mean the plug is good. The key indicator is the suddenness of the drop..." I ohm-test … Electromagnetic and radio-frequency interference can be a real pain in the butt. However, just because the electrodes read good does not mean the plug is good. Spark plug wires can easily be visually inspected for tears, burns or black spots that may pinpoint a voltage leak. This test cannot be done with the spark plug wire attached. A spark plug bomb tester can test a bad plug and lead you to conclude it is serviceable. 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. 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. Types Of Spark Plug Wires. Any clue why the old wires are so much different. Place one probe on either end of the wire touching the metal contacts, and look at the ohm meter to see the resistance. The OHM Meter check is simple, readily available, and amazingly accurate in finding misfiring plugs. Touch the test leads together. Move the test leads apart. This value was simply published by the marketing company to suit their marketing and advertising needs. A meter value with a “k” following the number will require a conversion to a whole number. 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. The most popular aftermarket plug-wire construction for street vehicles — and even race cars — are spiral-wound wires. 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. 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. 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. Larry : Wrong about what? Original … Make sure it … 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. 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. The EMI and RFI suppression keeps the electrical noise of the ignition charge moving within the wire to a minimum. As the plug ages, values below 5000 ohms are acceptable. I suppose they could be the wrong ones? Look in the owner's manual to find the appropriate resistance for the wires. If the meter reading is anything other than what you saw in Step 4, the plug is bad. Reply Reply Author. 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. 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. The spark plug is fouled and shorted to ground or is open and the magneto, which is functioning normally, is unable to fire it. Over the years the demands on these humble wires have increased, and thus the technology wrapped into them has also advanced. they look the same, heavy duty with the braided ground wires. 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. That is a tough balance to strike on modern computer-heavy cars, or even racers with sensitive data logging equipment. At its basic level, the spark plug wire exists solely to transmit electricity from the coil or distributor to the spark plug. Champion seems to think tattoos are more important than their specifications or getting through their web site. A broken wire allows no electricity reading at all, which will cause the multimeter to register resistance as \"over limit.\" Spark plug wires are easily broken internally when being removed from the plug, as they can become attached to the spark plug. But once the plug’s resistance value exceeds 5000 ohms, the plug should be replaced. The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. OEM spark plug wires can generally have a resistance of 10kOhm/ft to 15kOohm/ft. It could have the tip missing or any of several other problems. Note the reading. Understanding your meter readings . Jump to Latest Follow 1 - 7 of 7 Posts. Early spark plug wires were very simple—just metal that conducted. 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. When spark plugs are new, the resistance value is between 500 and 3000 ohms. Do not touch the tips of the test leads or the vehicle ground. Today, let’s dive into spark plug wires and the developments in technology that these simple conductors have experienced over the years. The lower the resistance, the better quality conductor materials are used in making the spark plug wires. Tools Needed: Digital multimeter Use the digital multimeter, set to Ohms Ω. For new plugs, we recommend 4000 ohms as the maximum acceptable value. There wasn’t even insulation. The resistance of many wires is measured in ohms per foot. New Tempest (formerly Unison-Autolite) will measure 1000 OHMS. Headers are notorious for causing problems, so invest in some extra insulation to prevent your new wires from literally melting down. These Granatelli Motor Sports spark plug wire sets combine a solid core, which exhibits nearly zero ohms of resistance, with a … 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. 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. While it sounds pretty simple, the reality is that even vintage engines are quite picky about how each of these four items is attained. Found these 2 explanations in other forums about Spark Plug Wire Resistance and Ohms. I saw one little statement in an aviation forum that they use some sort of silicon carbide voltage dependent resistor and can't be … You can also measure the resistance of each spark plug wire, but like coils, values may vary between wire brands. 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