Repair And Fix it

Like most ponderings in automotive repair, the question of removing spark plug wires from a running engine isnt necessarily so much one of "could" as it is of "should." Technically, yes, you can yank the plug wires off of a running engine just as easily as you could one that isnt running, but it may not necessarily prove conducive to you or your cars good health.

You Could

Removing a plug wire from a running engine isnt likely to result in catastrophic engine failure, particularly if you put it back on shortly afterward. All spark plugs misfire from time to time, you just dont notice it because its intermittent, random and usually happens so quickly that the cylinders firing again before the engine has a chance to vibrate. So, intentionally creating a misfire by removing the plug wire for a few seconds or even a few minutes isnt likely to destroy anything on most engines.

Common Effects on the Engine

Most engines have a rubber ring on the front of the crankshaft called a harmonic balancer; on the outer edge of the balancer is a heavy, metal ring. When the explosions in the engines cylinders push down on the pistons, the forces they exert quickly accelerate the crankshaft. When that accelerations over, the crank tries to slow down, resulting in a constant cycle of acceleration and deceleration that manifests as vibration in the crankshaft. The metal ring on the balancer resists these sudden, but tiny, vibrations and keep the crank from tearing itself in two. Over a long enough period of time, a dead cylinder and the resultant heavy vibration will over-work the balancer, causing it to fail. Once that happens, you could be looking at serious damage to the engine.

Effects on the Converter

Your cars catalytic converter works something like a blast furnace to convert toxic gases produced by your engine into more inert forms that wont drown polar bears or grow fish with three eyes. The converter takes advantage of unburned fuel -- which is, itself, a pollutant -- coming from your engine and uses it to fuel the furnace in the converter matrix. More fuel means more heat. Killing the spark in one cylinder will drastically increase the amount of fuel pouring into your exhaust, which will, at some point, cause the converter to overheat and fail. The engines control computer will compensate for this to some extent, but you can count on extra fuel going into the exhaust.

Lean-Out

Depending upon the computers control strategy, disconnecting a plug wire and leaving it that way could seriously fry something. When the oxygen sensor detects excess fuel in the exhaust, your cars computer may assume that this represents a net excess of fuel through all the cylinders. It will respond by decreasing the amount of fuel injected to all of the other cylinders in order to get the air/fuel ratio back in line. The resulting lean condition will increase combustion chamber temperature, causing overheating, detonation in the engine and, eventually, complete meltdown. Most computers do have programming provisions to account for a dead cylinder, and wont react this way; but some dont, and theres no way to be sure unless you know exactly how your fuel injection system thinks.

Safety Issues

Before pulling the plug wire off of a running engine, bear in mind that your are, in fact, grabbing a live wire with about 40,000 volts worth of electricity coursing through it. Normally, this electricity will pass through the plug wire and race to the spark plug, which acts as a ground. But when you remove that ground, the spark is going to find the next, most convenient ground. If you happen to be touching the body of the car when you pull the wire off, then you become that ground. While electricity normally wouldnt arc through the insulation, even if it is a bit old and damaged, removing the primary ground will make that spark pretty determined to get out whatever way it can. Its not likely to kill you unless you have heart or nervous system problems, since the amperage is very low -- but the sensation is rather, shall we say, "life affirming."

The 1992 Dodge Colt is a two-door hatchback. If you are having problems with your 92 Dodge Colt, there are a few things you can do before you have a mechanic take a look at it. The spark plug on the engine is what sparks it to life. If you have a bad spark plug, you will need to replace it in order for the engine to fire.

Instructions

1

Turn off the Dodge Colt and pop the hood.

2

Locate the spark plug housing on the back of the engine. The spark plug housing is labeled for easy access.

3

Pull the spark plug from the housing with your fingers.

4

Touch the spark plug to your Dodge Colt to look for a spark. If the spark is blue, you need to replace the spark plug.

5

Pull the spark plug from the housing and replace it with a new one. Put the spark plug housing back into the engine and then start the car.

Plug wires arent the most glorious part of any engine, but they are a bit more complicated than most give them credit for being. While wire length may not seem particularly critical, those wires carry an enormous amount of high-voltage power. Pay close attention to your plug wires, or they may end up sending a message that leaves you saying "Can you hear me now?"

Plug Wire Factors

Two things come into play when discussing spark plug wire length: the resistance of the wire in ohms, and the amount of radio frequency interference it produces. The ohm is a measure of a wires efficiency in passing electrical current. Smaller and less-efficient wires rate higher in ohms, meaning that theyll convert more electrical energy into heat in the plug wire instead of passing it to the plug. Resistance in the plug creates a discharge of positive radio waves, which ground out in a cars stereo system and create static through the speakers.

Ohms and Wires

Different grades of wires produce various levels of ohms per foot. An average stock spark plug wire creates about 5,000 ohms of resistance per foot of length; high-performance wires will average between 100 and 400 ohms, and high-grade race wires may go as low as 2 to 10 ohms. If you apply Ohms Law of voltage loss (Voltage Loss = amperes flowing through wire X ohms of resistance) to a typical high-performance ignition system where the coil produces about 20,000 volts and sends about 0.010 amps to the wires, youll find that a stock wire will cause a drop of about 50 volts per foot, a performance wire will drop about 1 to 4 volts per foot and a race wire might drop as little as little as 0.02 volt per foot.

Voltage Output and Plug Length

Since resistance to flow increases by wire length in feet, multiplying the spark plug wires length in feet by its voltage loss per foot will tell you its impact on spark plug power. In the worst-case scenario, assume that a stock 5,000-ohm wire measures a whopping 4 feet long. Thats a 200-volt drop from ignition coil to plug wire -- a seemingly insignificant 1 percent drop. However, that 200-volt energy loss will go into creating heat in the wire, and ohms of resistance go up with heat. The end result is a cascade effect of failure; the current flow and heat gain will eventually reach an equilibrium, but not before producing a noticeable drop in current, damaging the wires conductive core and hindering its RFI-suppressive qualities.

RFI and Solutions

You can get away with using longer plug wires by using a lower-resistance wire, one thats either thicker or higher quality. However, higher current flows also produce more RFI, which means that youll also need to use a high-quality RFI-shielded wire to prevent interference through the radio system. Even if you never listen to anything but MP3s and CDs, remember that RFI interference is an extremely broadband signal. Under certain circumstances, this signal can reach into the frequency ranges commonly used for cell phones and other communications devices, effectively scrambling the signal. So, if your phone seems to constantly drop calls while in the car, you might want to take a look at those old, cheap or mile-long plug wires.

Knowing a spark plugs specifications is crucial to understanding how the engine operates. A spark can make an engine run well, or it can damage it with pre-ignition. If you do not use the plug with the correct rating, your car will not operate properly.

Why Plugs Need Ratings

Different spark plug lengths are compatible with cylinders of different sizes. Different engines also require plugs with different spark ratings. Depending on the engine, choosing the right plug ensures the fuel burns efficiently once the piston compresses it against the cylinder cap.

Sparks also indicate whether the engine is burning fuel properly. If the fuel is burning too lean, the spark plug tip will show a chalky white residue. If it is burning too rich, the plug will be black or oily.

Spark Specification Coding

Sparks are usually coded in four digits. The first letter is thread diameter code. This lets a user know the plug will fit right in the engine socket or not.

The second digit is a number for the heat rating (the lower the number, the hotter the plugs spark).

The third letter is a digit for the length of the plug (short or long). Smaller engines tend to use a shorter length that screws into the cylinder cap.

The fourth digit is for any special codes of manufacturing company differences and brand identifications.

Lastly, if a fifth digit exists, it represents the electrode gap measurement.

Using the Wrong Plug

While spark plugs are generally designed similarly enough that they can be used interchangeably, doing so is not a good idea. The wrong specification will mean the spark plug will run too hot or too cold and foul.

Running too hot is more serious; a hot spark plug will cause pre-ignition which makes the engine misfire and can melt a hole in a piston.

The ignition system of an internal combustion engine delivers an electrical spark from a coil through a wire between the coil and the center post of a distributor cap. The spark then travels through a rotor on top of the distributor shaft and back through individual posts in the outer ring of the distributor cap, through the spark plug wires and to the spark plugs. If an engine does not start, or is constantly missing on one or more cylinders, chances are good that the problem is with the electrical spark to the spark plug. The only way to find the problem is to check the electrical spark at the distributor and coil, working out toward the plugs.

Instructions

1

Push the spring-loaded hooks on each side of the distributor cap down and turn them counterclockwise 90-degrees with a screwdriver to loosen the distributor cap. Lift the distributor cap off. Pull the rotor off the end of the distributor shaft.

2

Attach a jumper switch to the vehicles starter. Bump the switch until one of the lobes on the distributor cam aligns with the nylon cam follower on the ignition points. At this point the points should be open rather than together. Inspect the ignition points to ensure that there is no corrosion that will prevent electricity from flowing through them. If there is any corrosion on the points, replace them.

3

Slide a feeler gauge between the two open contacts on the ignition points. Ensure that the thickness of the feeler gauge is equal to the factory-specified gap setting. If the gauge does not fit between the contact points, or the gauge is too loose, adjust the points by loosening the adjustment screw, adjusting the mounting plate toward or away from the distributor shaft until you achieve the proper point gap. Tighten the mounting screw.

4

Inspect the rotor for burning or corrosion anywhere on the brass, mounted on the plastic rotor. If you find any burning corrosion, clean the rotor with a file or replace the rotor if the pitting from the corrosion is too deep.

5

Inspect the distributor for the same type of burning or corrosion. Clean or replace the distributor cap as needed. Reinstall the rotor on top of the distributor shaft. Reinstall the distributor.

6

Unplug the spark plug wires from the spark plugs by twisting them with a plug wire pliers and pulling them off the top of the spark plugs. Turn the vehicles ignition switch to the "on" position. Remove the thick black wire between the coil and the distributor, known as the coil wire, from the end of the coil. Hold the coil wire close to the coil with the plug wire pliers while operating the starter with the jumper switch. A spark should jump from the coil to the coil wire. If there is no spark between the coil wire and the coil, replace the coil and retest.

7

Plug the coil wire back into the coil and disconnect it from the center post of the distributor. While holding the coil wire with one hand and operating the jumper switch with the other, ensure that there is a spark between the coil wire and the distributor cap. If there is no spark, replace the coil wire with a new one, then retest.

8

Plug the coil wire back into the distributor. Pull one of the spark plug wires out of the top of the distributor. Hold it with the plug wire pliers and test as before. Repeat for all of the spark plug wires. If there is no spark between the distributor cap and the wires, replace the distributor cap and rotor, then retest.

9

Replace all the spark plug wires on the spark plugs. Start the engine. Remove the spark plug wires one at a time from the spark plugs and listen to engine performance. If an engine is missing, there is no perceptible change in engine idle when the plug wires removed, there is no spark between the wire and plug and there is a spark between the plug wire and the distributor, replace the spark plug wire.

The spark plugs on the 2001 Toyota Tacoma motor are designed to supply the spark needed to the combustion chamber during the combustion process. The spark ignites the gas fumes and causes the combustion which in return causes the piston to move up and down. When the engine is running, the coil sends the electrical current to the spark plugs that causes the plugs to spark. Over time the spark plus will begin to corrode around the spark base causing the plugs to misfire. Once this happens, change the spark plugs out immediately for maximum engine performance.

Instructions

1

Open the hood and locate the row of spark plugs on the driver side and passenger side of the engine. The 2001 Toyota Tacoma comes with basic spark plug wires on the driver side of the engine and ignition coil plugs on the passenger side of the engine. Start replacing the spark plugs on the driver side of the engine.

2

Pull the first spark plug wire off of the driver side spark plug closest to the front of the vehicle. Insert the deep-well socket and the six-inch extension onto the spark plug. Lock the ratchet onto the extension and turn the ratchet counter clockwise to loosen the spark plug. Remove the ratchet and finish unscrewing the plug with your fingers. Pull the spark plug out of the hole and discard it.

3

Screw the new spark plug into the hole with your hand until it stops turning. Continue to tighten the spark plug another half-turn with the ratchet, extension and socket to properly tighten the plug. Push the spark plug wire over the new spark plug until it locks on to the end of the plug. Move to the other driver side spark plugs and repeat the same process for replacing the plugs one plug at a time.

4

Move to the passenger side of the engine and unscrew the top of the ignition coil wire from the first spark plug closest to the front of the vehicle with your hand. Pull the wire off of the spark plug and insert the spark plug socket, extension and ratchet onto the plug. Turn the ratchet counter clockwise to loosen the plug. Remove the ratchet from the plug and finish unscrewing the plug with your hand. Pull the plug out of the hole and discard it.

5

Screw the new spark plug into the hole until it stops turning. Finish tightening the plug by turning the plug another half-turn with the ratchet, extension and socket. Push the ignition coil wire back onto the top of the spark plug wire and screw the top of the coil wire onto the spark plug clockwise until the end of the coil wire is tightened to the top of the spark plug. Move to the other passenger side spark plugs and repeat the same process for replacing the spark plugs one plug at a time.

6

Inspect all of the plugs and plug wires to ensure that all of the plug wires are securely attached to each spark plug. Crank the vehicle for about thirty seconds to test the operation of the new spark plugs. The engine should be running smoothly with the new spark plugs in place.

If your vehicle isnt starting when the engine is turning over, you may not be getting spark to the spark plugs through the ignition coil. You can check this by performing a simple test. This task is relatively easy but you will need an assistant so that you can simultaneously perform some of the necessary functions detailed in the procedure. Figuring out the cause of the problem that you are experiencing with your vehicle is half the battle.

Instructions

1

Park your vehicle on a flat surface.

2

Open your hood to access your engine compartment.

3

Pull the nearest spark plug wire off the top of the spark plug to expose the end of the wire

4

Connect the exposed end of the wire to the top of an extra spark plug. Set the spark plug against one of the metal surfaces on the engine.

5

Ask your assistant to start the vehicle. If you see a spark come from the spark plug, then there is spark coming from the ignition coil because the wire is attached to the ignition coil.