An Ohm meter, which is part of a multimeter, can only check a spark plug for a short circuit or a breakdown of insulation resistance. A good spark plug should show an open circuit between the center electrode and the tip. Any resistance at all would mean the plug is bad.
Use a “safety” screwdriver, one with a rubber or plastic handle cover. Put the screwdriver in the unattached end of the plug wire, and hold the rest of the screwdriver near a metal surface. Get someone to attempt to start the engine and you should see a strong blue spark jump from the plug to the engine.
Loss of spark is caused by anything that prevents coil voltage from jumping the electrode gap at the end of the spark plug. This includes worn, fouled or damaged spark plugs, bad plug wires or a cracked distributor cap.
When the ignition coil pack becomes worn or damaged the car’s computer system will engage the “Check Engine” warning light. When the ignition coil pack fails it doesn’t send the necessary volts to spark plugs which in turn ignites fuel and air mixture in the combustion chamber.
An engine’s condition can be judged by the appearance of the spark plug’s firing end. If the firing end of a spark plug is brown or light gray, the condition can be judged to be good and the spark plug is functioning optimally.
Each piston inside of your car’s engine has two compression rings and an oil control ring. If the rings are worn or stuck, oil will be able to enter the combustion chamber, resulting in wet oil and/or ash deposits on the tip of the spark plug.
Use a digital or analogue multimeter (or ohmmeter) to check if the resistance of each spark plug wire is within the manufacturers’ guidelines. … To do this, set the multimeter to the appropriate scale and measure the wire by placing the probes on each end of the wire lead, making sure they touch the metal contacts.
The meter should read 6,000 to 15,000 ohms. If it does not, the coil’s secondary winding is faulty. Remove meter’s probe from the center terminal and touch it to the terminal bolt on the opposite side of the coil from the probe touching the grounding terminal. The meter should read between approximately 0.4 and 2 ohms.
since a faulty ignition coil causes a misfire, it will also cause the related spark plugs to foul. always replace the spark plug or plugs that the bad coil was firing. this will restore the power and fuel economy.
Changing spark plugs takes about an hour (for a four-cylinder engine) and will save you at least a hundred bucks in labor if you do it yourself. In most cases it’s a simple job that will help to maintain peak performance and the highest possible gas mileage.
Once your vehicle receives new spark plugs, you’ll notice how much better your car feels while driving. … Increased Fuel Economy – Misfiring spark plugs can reduce fuel efficiency by as much as 30%. New plugs that are replaced at regular intervals maximize fuel economy, saving you money.
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