Keep in mind these are generic values and may vary between vehicle manufacturers and spark plug wire manufacturers. Connect test leads to the multimeter by plugging them into the jacks. Higher readings indicate too much resistance, possibly because of rusting or faults in the wire. they look the same, heavy duty with the braided ground wires. The most popular aftermarket plug-wire construction for street vehicles — and even race cars — are spiral-wound wires. If you have any additional tips, be sure to leave them in the comments below. The spark needs of a stock 216-cubic-inch inline-six Chevrolet are drastically different than those of a supercharged big-block Ford. The carbon fibers produce minimal RF noise, however they have high resistance. 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). That pinging noise is the radio-frequency interference from an uninsulated plug wire. Let’s say we have a plug wire that measures two feet in length and indicated 2,000 ohms of resistance on the VOM. That is a tough balance to strike on modern computer-heavy cars, or even racers with sensitive data logging equipment. 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. Make sure it … The easiest way to test your spark plug wires is by using an ohm meter to measure resistance. To perform a wire resistance test, connect an ohmmeter across each end of the wire. Champion seems to think tattoos are more important than their specifications or getting through their web site. Also, all the shielding inside a wire is not free. NGK plugs are 5k ohms, they made that easy to find. 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). Ignition systems which use a magneto are often best served by the lowest resistance wire possible. 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. Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. If the meter reading is anything other than what you saw in Step 4, the plug is bad. There is more to consider though. 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 wires can easily be visually inspected for tears, burns or black spots that may pinpoint a voltage leak. If we divide 2,000 by 2 — we get 1,000 ohms of resistance per foot. Spark plug resistance. You can also measure the resistance of each spark plug wire, but like coils, values may vary between wire brands. This test cannot be done with the spark plug wire attached. 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. A typical bad plug will cause an immediate drop of 250 or more RPM, at the mag check. 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 Society of Automotive Engineers suggests the maximum resistance should be 12,000 ohms-per-foot. Do not touch the tips of the test leads or the vehicle ground. 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. Yet again, not quite. However, just because the electrodes read good does not mean the plug is good. What's New 3 12 24 72. 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. 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. A good spark plug should show an open circuit between the center electrode and the tip. A good spark plug should show an open circuit between the center electrode and the tip. 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. It’s not a difficult process; it just takes a bit of patience and attention to detail—like any other automotive project. If it falls within the manufacturer's measurement range in your repair manual, the plug wire is not your problem. This is because your "wires" aren't really wires at all but conductive plastic or fiber. Take a reading in kilohms (1 kilohm=1,000 ohms). There wasn’t even insulation. While it sounds pretty simple, the reality is that even vintage engines are quite picky about how each of these four items is attained. Look in the owner's manual to find the appropriate resistance for the wires. The OHM Meter check is simple, readily available, and amazingly accurate in finding misfiring plugs.