How To – Changing Spark Plug Wires

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    Maintaining your car is not always difficult or expensive but repairing problems once they happen can cause headaches and eat into your spending money. For this reason you should perform routine maintenance as your manufacturer suggests and while doing so you may want to change other worn parts that are easily accessible.

    Many new vehicles do not use standard spark plugs anymore but if your car is more then a few years old it is important to replace these wires when you perform a tuneup.

    How often should you change your spark plug wires? Every 60,000 miles is not out of the question and at that point you probably want to replace some other ignition parts including your Cap, Rotor, Spark Plugs and while you are at it you should inspect the other wear items on your car such as your Accessory / Fan Belts, Air and Fuel Filters.

    The way some people drive today 60,000 miles might come every year but for the rest of us you can expect to perform this work every 3 years.

    REMEMBER ALWAYS FOLLOW YOUR VEHICLES SPECIFIC MAINTENANCE SCHEDULE.
    If you don’t know it then contact your dealer.

    Buying Your Parts

    Spark Plug wires are the way high voltage electricity is passed to your engines spark plugs in each of your cylinders. This means if you have a 4 Cylinder engine you will need 4 spark plug wires and depending on your cars design a coil to distributor wire. If you have a 6cyl you will need six wires if you have an 8cyl then you need 8 wires.

    When you go to purchase your wire set all the necessary wires will come in a box ready to install.

    You will need to know the make, model and engine size of your vehicle to order your parts. This information is located in your Owners Manual or possibly on drivers side door tags. If you have changed your engine or have questions about finding the correct information you can visit your local dealer and have a service manager take a quick look and tell you or you can visit your parts distributor and they will inform you.

    Once you have the correct information you can begin shopping for parts. When possible you want to use OEM Original Equipment Parts or better parts. There are a handful of large manufacturers of Auto Parts and you will quickly know their names while you shop at different parts distributors for the best price.

    OEM Spark plug wires or sometimes called (original fit wires) will match your engine in size very closely to the ones that the manufacturer installed. Because they are Molded and then tested in the factory they will also seal better then some performance parts depending on the installation so they are a good feature to look for.

    Universal or Build Your Own Wires for general use really suck… stay away from them unless you know you definitely need them. They require that you understand how to build the wire to fit the application. If you are building a high performance vehicle they may be your only resort.

    If you do not have a high performance vehicle, that you actually race, then you do not need high performance parts. These parts may have some qualities that are worth the extra money if you are racing your vehicle but if you are simply performing maintenance there is often no need to use higher priced parts that may not work well with your other standard engine items.

    Getting Started

    If this is your first time and maybe even if it isn’t you should start by numbering your spark plug wires with tape labels.

    Each spark plug in your engine has to fire in a specific firing order. It is extremely important that you do not cross / mixup the order of the wires.

    Your labels do not need to match the firing order they just need to correspond between the wire and the connection.

    Mark each wire on its boot where it enters the distributor and mark the distributor to coincide with the wire.

    You should also make a quick drawing of the routing of your wires. You can also take pictures but a drawing may help more since you won’t have to run to your computer to look at the pictures and run back outside and try to remember what you just saw.

    Pre-fitting the Wires

    Most wire sets will have wires that are all of a different length.

    Sometimes the difference in between wire lengths may be as small as an inch or two and on some vehicles the length of the wires may be the same but the boots / connectors on the wires where they pass near things like a hot exhaust manifold may be different.

    Before you remove any wires from the distributor or the spark plugs you should layout each wire and inspect it for length and close fit.

    Installing the Wires

    When you start replacing the wires you want to do it one at a time.

    Take one wire off of the coil and trace it back to the spark plug. Remove it from each of the wire seperators as you go.

    Now replace that wire with your new wire.

    When the connector on the wire attaches to the coil or to your spark plug you will feel and maybe hear a small snapping noise and feel it lock into place.

    If the wire seems loose you may need to adjust the connector by crimping it with a pair of pliers on the spark plug end or using a screwdriver to expand the connector on the coil side.

    The directions that come with your wires will explain this.

    IMPORTANT once the new wire is in place take the labels from the old wire and transfer them to the new wire before you go to the next wire. Yes overkill but do it… at least the first few times you attempt this job.

    Never think you can do more then one wire at a time even if you are having routing problems.

    If you find that you removed a wire that needs another wire taken off  so you can gain access then put the first wire back on the distributor or plug and remove that other wire individually.

    Yes this can be time consuming and seems like overkill but if you mixup your wires you will need to have a diagram available to reattach them in the correct order. If you don’t attach them in the correct order you could do damage to your engine or your engine will not start.

    Final Note

    Replacing your Spark Plug Wires is something you can do and it will save you about 50% on the cost of parts verses parts and labor you would spend with a mechanic.

    You should use that money you save by putting it towards another part that needs to be replaced.

    Shopping Online for parts is also a good deal but only after you know the exact part and model number of the item you need to purchase. If your Parts Distributor tells you that you need SuperWire Set #123890R then you need to make sure you order that EXACT part number online and don’t accept any other… #123890R #123890Z are not the same…….

    No matter where you buy your parts always understand the return policy.

    Automotive Electronic Parts may be sold as a no return item Or it may be sold as exchange for the same item only.

    The YouRepair Store sells Parts for your car at great Discounts

    Ignition Parts

    Spark Plugs & Wires

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