See full version: Live Wire: How to Choose Spark Plug Wires for Your Vehicle
Spark plug wires can’t add horsepower (despite what some may claim), but they can adversely affect your vehicle’s performance. That’s why it’s important to select a good quality set of spark plug ignition wires to deliver juice to your spark plugs.
MSD 8.5mm Super Conductor wire sets use a special helically wound core that has just 50 ohms of resistance-per-foot but offers RFI suppression equal to a 1,500 ohm wire. That's the advantage of a spiral core.
Some wires are made to produce minimal resistance. Others are designed to suppress EMI. Spark plug wire manufacturers use different core materials and designs to strike the right balance to achieve their desired goal. here
Spark plug wires with bad insulation affect engine performance, especially during damp weather on rainy days. This test will check your wires' insulation for voltage leaks. here
Note: For the next two tests, work on one spark plug wire at a time. That is, disconnect one wire, proceed with the two tests, reconnect the wire, and then test the next wire. This way, you'll plug each wire back to its corresponding cylinder. If you don't, you'll upset the firing order of the ignition system, and the engine won't operate properly, if at all. [links]
Pay attention to any spark or electric arc jumping off the insulation toward the tip of the screwdriver. Even if you can't see the arc, you'll hear a cracking sound as the spark jumps to the screwdriver, so pay attention to any sounds as well. [links]
Still, failing or bad spark plug wires share their symptoms with many other engine components going bad. So you need to verify that you actually have one or more damaged or worn out ones. more
To check the wires, apply the next series of tests before deciding to spend money on a new set of wires. here
Spark plug wires can also be upgraded to high performance replacements if modifications are made to the ignition system.
Step 5: Visually check the spark plug wire for damage. Look for any signs of melting or cracking. more
Step 12: Start the engine. Verify that there are no running issues with your vehicle.
Step 11: Push the spark plug wire onto the coil or distributor cap. Again, you should feel it snap into place.
Step 8: Install the spark plug wire using the same routing that it was originally in. Make sure that the spark plug wire does not get too close to other electronics, or on anything hot such as the exhaust. [links]
On engines that are equipped with a distributor or a remote coil pack, spark plug wires are used to transfer the spark from the coil to the spark plug. The wire can be several inches or several feet in length. Spark plug wires are typically constructed with a silicone jacket that keeps them insulated and resistant to high temperatures, and have internal shielding which keeps them from producing any electrical interference.
Having a spark plug wire with bad insulation may not be as bad as a wire with a broken conductor. Still, this is enough for your ignition system to cause all kinds of engine performance problems, especially during damp weather. This test will help you check your wires for voltage leaks. [links]
Note: For the next two tests, work on one spark plug wire at a time. That is, disconnect one wire, proceed with the two tests, reconnect the wire, and then test the next wire. This way, you'll plug each wire back to its corresponding cylinder. If you don't, you'll upset the firing order of the ignition system, and the engine won't operate properly, if at all. [links]
Yet, miles of service and the harsh environment in which these wires operate has its toll. The internal conductor breaks or burns, failing to deliver the necessary voltage to them. The insulation deteriorates, leaking voltage to nearby wires or metal surfaces (ground), leaving the plugs with a weak spark or no spark at all. more
Testing spark plug wires helps you diagnose common engine problems, such as:
Checking spark plug wires for better engine performance. here
Spark plug wires deliver thousands of volts (up to 50,000 or more) to the spark plugs. To carry such large voltages, plug wires need to have some basic physical characteristics. For example, thick insulation to prevent high voltage from jumping off the wire before it reaches the spark plug, and a rubber boot at each end to protect metal connectors from moisture, corrosion, oil, and other contaminants.