We’ve all done it at some point – you’re cruising along on I-95 when suddenly you realize you forgot to replace the spark plugs! Without thinking twice, you yank off the offending plugs (and hope they don’t start smoking!) and throw ’em under the seat until you reach home. But what if there was another way to do this? What if you could simply tap out the bad ones with no tools? It turns out that’s exactly possible…but only after we take care of a few things first.
The main thing you’ll want to know about getting a lost or broken spark plug out of its mounting location before trying anything else is how to tell which wire goes where. Each cylinder of most cars today have four wires coming out of each spark plug; these are usually color coded as follows:
Positive (+) leads
These are used to power the spark plug itself. They connect directly between the center electrode and the top terminal post of the spark plug. When working correctly, these should be cleanly stripped away once removed. If left behind, however, it can cause serious damage to your vehicle’s electrical system.
Negative (-) lead
This is also known as “ground” because it provides current flow back toward ground through the ignition coil. The negative lead connects directly to the bottom terminal post, below the positive lead. Again, these should be cleanly pulled free without being damaged. In fact, pulling too hard on either of these connections can actually short circuit your ignition system causing severe damage.
Spark control/Ignition control
In modern engines, two more very important wires run together within the head of the spark plug. These wires provide timing information and act as controls over when sparks occur. A good rule of thumb here is to pull gently on both ends of the wire so as not to accidentally strip the insulation off. Once the wires come loose, hold onto them and use tweezers to push them outwards while simultaneously pushing against the mounting screw heads on opposite sides of the mount. Be careful not to touch the actual wires themselves since doing so might result in burning yourself.
Capacitor Control Lead
Also known as “coil”, this third wire carries signals indicating whether the capacitor bank is charged or uncharged. Most people rarely notice this signal other than during periodic checkups such as oil changes or tune-ups. However, if the capacitors go dry, the spark plug must remain grounded. Pulling on this wire too much can create a dangerous situation where it shorts across the hot spark plug terminal posts, potentially damaging wiring underneath. Instead, use tweezers to carefully lift the plastic insulator covering the wires and twist them apart. Then use pliers to grab the bare copper wire and pull it out.
Once the above steps have worked their magic, it is now safe to remove the remaining parts of the old spark plug. First, pick up a new set of replacement spark plugs just like the originals. Next, begin prying the old screws out with a thin blade knife or even a small screwdriver. After everything comes loose, inspect the threads inside the holes for signs of wear and tear. If you find cracks, chips, or gouges, you’ll probably need to replace the entire shaft rather than repair it alone. Remember to always work slowly and cautiously when handling live electricity — never attempt to stick your fingers into any exposed terminals or screw heads.
Now that you know why you shouldn’t mess around with your own auto maintenance, let’s review the safety tips needed for dealing with a stuck spark plug. Before attempting to fix a problem yourself, make sure to turn off the key and disconnect the battery cable. Also, keep children and pets far away from the area where you plan to remove the old spark plug and dispose of any shavings properly. Finally, remember to follow the manufacturer’s guidelines for installing new spark plugs. For example, Chevy Spark owners should ensure that their spark plugs are installed straight instead of angled. Angled plugs tend to allow gases trapped beneath the tip of the electrodes to accumulate near the gap. As a result, excessive pressure builds up between the electrodes, eventually leading to premature breakdowns.
It doesn’t matter if you’re changing spark plugs or fixing a leaky radiator hose, gloves are essential whenever working with electric motors or electronics. To prevent burns or shocks, wear rubber-soled shoes, long sleeves and pants made of non-conductive material, eye protection, and earplugs. Never leave any kind of open container full of gasoline unattended. And never smoke or eat while operating machinery.