Common causes of ignition wire failure that are eliminated by using Magnecor ignition wires are:

* Carbon conductors wearing out and burning back in original equipment and aftermarket wires;
* Spiral conductors burning back from pin-type terminations in European and Japanese original equipment and aftermarket wires;
* Spiral conductors burning back from core-crimp (also know as “dual crimp”) terminals not properly terminated;
* Resistor-connectors burning out in German original equipment and aftermarket wires;
* Insulation jacket breakdown under braided metal sleeves fitted to so-called “built-in capacitor” wires.

Additional common causes of ignition wire failure that include Magnecor ignition wires are:

No proper engagement of the spark plug, distributor, and coil terminals —the most common installation problem. This problem is not always immediately noticeable when using Magnecor Race Wires, because the high capacity conductors do not reduce spark energy like carbon conductors. In most cases, if an engine miss does become noticeable, and the ignition wires are determined to be the cause, the problem can be simply solved by ensuring connectors are properly engaged. Often, by looking into the spark plug end, a black substance will appear on a normally shiny terminal if it has not been engaging the spark plug top properly for some time. Fitting instructions are always included in Magnecor ignition wire set packages, together with additional instructions for engines with a history of ignition wire failures due to the difficulty of installation and other causes including moisture accumulating in deep spark plug holes.

Any ignition wire can be damaged if care is not taken when removing it from a spark plug or distributor/coil. The most common damage to an ignition wire occurs when the ignition cable is wrenched out of a spark plug terminal locked onto a spark plug top. Generally, it’s in the best interest of every ignition wire manufacturer to make every effort to ensure the terminals are crimped onto the cable as tightly as possible. Magnecor wires even come with a variety of terminals that are designed for specific applications to help overcome the problem of terminals locking onto spark plug tops, but all too often, someone still  manages to wrench the cable from a terminal locked onto a spark plug top.

Keep in mind, the longer the spark plug wires have been attached to the spark plugs, the more careful you will have to be when removing them, as more effort will be needed.

Experienced auto technicians rarely damage spark plug wires during the removal process, but the DIY’ers regularly damage wires because of inexperience and lack of know-how, particularly if they have never removed wires from spark plugs before. The first thing to remember is that unless it’s an emergency, NEVER REMOVE IGNITION WIRES UNTIL THE ENGINE IS COLD, as hot spark plug tops will expand and lock into the terminals inside the wires’ spark plug connectors. Always try to pull a wire’s spark plug connector straight off the spark plug, and not at an angle, as the connector’s metal terminal can bite into, and lock onto the spark plug top, particularly if the spark plug has a soft metal top. Do not rock rubber boot and terminal combinations to free the terminal from the spark plug top, as the mouth of the metal terminal inside the boot can be spread if enough force is used, and thereafter, the terminal will be loose on the spark plug top. On engines with extended spark plug connectors to reach spark plugs down deep holes, always remove the wire’s cable from retaining/separator clips before pulling on the spark plug connector, as failing to do so can cause the connector to be angled over when being pulled from the spark plug. The same care should be taken when removing distributor/coil connectors, as most are made of brass and can be eventually be broken by rocking back and forth to remove the boot from the distributor or coil. NEVER PULL ON THE WIRE’S CABLE.

Combustion gases leaking past spark plug gaskets and spark plug porcelain seals (and cracks) can cause wire boots and connectors to pop of spark plugs. Also, the opposite can occur if, over time, a small amount of corrosive combustion gas continues to leak from around the very top of a spark plug porcelain to cause a galvanic action, which binds the wire’s metal terminal to the spark plug top, and if enough force is used, the cable can be wrenched out of the terminal in an endeavor to remove the spark plug boot/connector. Small size spark plugs are prone to this problem in turbocharged and supercharged engines.

IMPORTANT: It is good practice to let any engine cool before spark plug boot/connectors are pulled off the spark plugs, as often, when engine is hot, certain spark plug tops will expand more than the stainless steel terminals inside the boot/connectors. Whenever a spark plug top expands (and locks) inside a terminal, any attempt to forcefully remove the wire connector from the spark plug will usually result in the cable being wrenched out of the terminal, with the terminal remaining locked to the spark plug top. Unfortunately, silicone rubber will never be as strong as stainless steel.

Extended multi-part plastic spark plug connectors used mostly on Japanese engine ignition wires can be terminally damaged by arcing over the plastic extension tube of any connector whenever moisture accumulates in the spark plug hole. This style of connectors can also be pulled apart if pulled to one side and brute force is used to remove them. A surprising number of owners and installers attempt to remove extended connectors from the spark plugs without first unclipping the wires from retainer/dividers, a practice which inevitably causes connectors to be pulled up at an angle. Some spark plugs have oversized soft metal tops that work well with the loose-fitting light gauge terminals used on some Japanese original equipment wires, but care needs to be taken when removing Magnecor Race Wires with heavy duty stainless steel terminals (needed for high-output race ignitions) that can be locked onto soft spark plug tops if connectors are not pulled straight up, and deep scouring of the spark plug top occurs. Also, some extended connectors contain an original style terminal which can be unlocked inside the plastic tube if a connector is twisted (for removal) in an attempt to free a terminal locked onto a spark plug top.
Again, always wait until engine cools before removing spark plug connectors.

Excessive oil from leaking valve cover draining into spark plug holes and filling up to the bottom seals of extended multi-part plastic spark plug connectors can cause the bottom seals to un-glue themselves from the plastic extension tubes when the connectors are removed. The only real cure for this problem is to replace the leaking valve cover gaskets. Generally, if there is no crazed arcing tracks over the plastic extension tubes, the oil-soaked connectors can be re-used if you are able to re-glue (with RTV silicone adhesive) the detached seals to the end of the plastic extension tubes after the seals and tubes have been thoroughly cleaned with grease removing cleaner (do not soak them in a solvent), and as much as possible of the old RTV is removed. You can also send for new seals if the detached seals are too swollen. Alternatively, you can send the wires to Magnecor for new seals to be re-glued onto the extension tubes —please leave it to us to clean off the oil. Evidence of leaking oil is usually obvious on the spark plug connectors.

Too much silicone dielectric grease placed inside extended multi-part plastic spark plug connectors can cause them to pop off spark plugs or disconnect from the spark plug top without popping off the spark plug. This problem can also occur if too much grease is stuffed into flexible rubber boot connectors. Only occasionally will a flexible rubber boot connector completely pop off the spark plug, but if the terminal inside is swamped in dielectric (insulating) grease, it won’t properly engage the spark plug top, and misfiring will occur.

All too often, when wires are sent to us for evaluation (particularly on engines notorious for moisture accumulation in spark plug holes) we see far too much grease stuffed into the spark plug connectors. Always keep in mind that grease cannot be compressed, and there’s no room in a spark plug connector for too much grease and the spark plug as well. Only a film of grease should be applied at the mouth of a multi-part plastic connectors’ bottom seal or at the base of the spark plug’s insulator to help prevent moisture seepage. Unfortunately, the heat from the spark plug porcelain will eventually cause the grease to seep out of the seals, so it needs to be applied on a regular basis it your vehicle is driven in the rain for long periods of time or you live in an area (such as near the sea) where condensation accumulates all over the engine without it raining. It is important that only silicone dielectric grease is used for this purpose, as other greases can become conductive. Realistically, it’s better not to use silicone grease at all in spark plug connectors unless you know there is a moisture problem with your engine.

If your engine develops a misfire after you have put grease into the spark plug connectors, remove the connectors and look into each connector’s mouth. If any metal terminal inside a connector has grease in it, remove it as best you can with a cotton Q-Tip swab if you don’t want to replace the wire. It is better not to attempt to wash it out with a solvent unless you know for sure that the solvent won’t harm the connector materials.

Fitting spark plug boots too close to 1,500 degrees F (815 degrees C) plus headers (exhaust manifolds, extractors) and turbocharger plumbing is another problem encountered on modified production engines. Some header aftermarket designs make it impossible to fit spark plug wires without the spark plug boot touching the header. Currently, the best silicone rubber spark plug boots are limited to 600 degrees F (316 degrees C), and ceramic boots don’t really help because they need to use rubber seals to prevent arcing. Various fiberglass covers can help, but in extreme situations where there is little or no airflow, the fiberglass can almost reach the temperature of the heat source, and for this reason, tight fitting fiberglass sleeves over the cable jacket are virtually useless for heat protection.

Recently, spark plug boots onto which a mildly reflective metallic coating is applied have been promoted as being able to withstand up to 1,000 degrees F (538 degrees C), and although this figure is an exaggeration, these boots will certainly tolerate more heat. The downside is the boot’s coating is conductive, and during our evaluation of whether or not to use these boots on our wires, we discovered there will be times when the spark energy finds it easier to induce itself into the boot’s coating (and ground out to the spark plug base) than to fire a spark plug with a wide gap (electrode gap deliberately widened or worn away) —causing the engine to misfire.

Our customers have reported that loose-fitting highly reflective coated fiberglass sleeves slid over spark plug boots can help in some cases. Thick loose fitting fire sleeve fitted over the spark plug wires are very effective on race engines, but generally it’s bulk makes it impractical for use on a street engine (and unsightly on a well presented street car engine). By far the best solution for heat related problems with all engine wiring is to shield, wrap or coat the heat source itself, and to introduce more airflow around where the spark plug wires are located.

Most parts used to make Magnecor Race Wires are available as spare parts. Excessive-heat damaged boots can be replaced at our factory or ordered as separate items. Wherever possible, Magnecor Race Wire sets for certain engines will include modifications to original design of the spark plug wires to help overcome the problems caused by poor original wire and/or engine design.

Battery acid can can attack ignition wires if it’s allowed to remain on wires, boots and/or connectors. If, for any reason battery acid finds it way onto the ignition wires (usually as a result of a collision or battery removal), the wires should be immediately washed down with water combined with baking soda (to kill the acid). Also, battery acid will attack skin and clothing.

Over the years, we have never ceased to be amazed how many people blame problems caused by spark plugs on the ignition wires. Ignition wires are nothing other than conductors of spark energy, and if the spark plug gaps are eroded or set too large, or a spark plug itself is defective for a variety of reasons, the energy conducted will be wasted. No spark plug lasts forever, and rarely, does any spark plug last as long as advertised, particularly if you want your engine to perform satisfactorily. Sometimes, spark plug problems can be disguised and postponed with stock wires, which provide suppression by reducing spark energy to the plugs, and sometimes spark plug problems can be made worse by Magnecor KV85 and R-100 wires designed to provide suppression without reducing spark energy from the coil (more so, with high-output ignitions). Unfortunately, all engines lose power if any or all spark plugs are not performing satisfactorily, no matter what ignition system or ignition wires are used.