The strength of the spark is revealed in the color. A red or yellow spark is weak and probably will not spark in the cylinder. A blue or white spark is strong and has enough voltage to fight across the spark plug gap even under pressure within the cylinder.
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.
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.
While most spark plugs for passenger vehicles should have somewhere in the 4,000-8,000 ohms neighborhood, your exact plug may call for different values.
If there's too much air in the cylinders at the time of the spark, and not enough fuel, the spark won't be able to ignite all the fuel at once. Yet again, leftover fuel vapor will flow into the exhaust and could combust there in a backfire.
A weak spark is the first sign that the ignition coil may be failing. During acceleration, the air and fuel that is forced into the cylinders extinguish whatever spark there is, which causes the car to stall.
Broken electrodes
A spark plug that is too long can cause extensive damage to your engine while a short spark plug can cause poor gas mileage and spark plug fouling.
Intermittent misfires are almost always caused by a weak spark or a lean fuel mixture. That piece of knowledge may not tell you what exactly is causing the misfire, but it should lead you toward a coil problem or an injector problem. Random misfires are another type of misfire that can be very difficult to diagnose.
A spark-ignition engine is an internal combustion engine, generally a petrol engine, where the combustion process of the air-fuel mixture is ignited by y a spark from a spark plug. A bright blue spark is best. A yellow/orange spark signifies weak ignition. The hottest spark is ultraviolet which we can't see.
In review, an oil-filled ignition coil requires about 3-5 amperes of current at 12 volts to produce 20-30 kV, while a modern e-core or coil-on-plug configuration might require as much as 10 amperes of current at 12 volts to produce 30-60 kV of high-intensity spark.
If your spark plug is white in color or appears blistered, that means something is making the plug run too hot. Check for problems in your engine's cooling, a lean fuel mixture or incorrect ignition timing.
Lean Air/Fuel Mixture
When a lean mixture combusts, it burns more slowly, meaning there will still be some air and fuel that isn't used up when the exhaust valves open -- leading to a backfire.
If too much fuel is added to the engine, it may not all burn up before the exhaust valves open -- letting unburned gasoline into the red-hot exhaust headers, where it can combust and lead to a backfire. Too much fuel could be getting into your engine due to damaged and leaking fuel injectors or bad engine sensors.
A misfire feels like your engine suddenly loses power. You might experience a hesitation when you try to accelerate the vehicle. If it feels like your vehicle is accelerating slower than usual or if it feels rough, the cause could be an engine misfire.
Ordinary copper and nickel spark plugs should be changed every 30,000 to 50,000 miles, unless otherwise suggested by the spark plug manufacturer. Platinum and iridium spark plugs tend to last longer than standard copper and nickel spark plugs. Expect to change them every 60,000 to 150,000 miles unless otherwise noted.
The overheating of ignition coils can hinder their ability to conduct electricity. Wear and tear is a common reason for ignition coils failing. It causes degrading of the insulation between the primary and secondary coil windings and the primary coil. The reduction in insulation can cause the coil to overheat.
It's important to remember that many times when a coil fails, it becomes weak. It still produces spark, and may still run the vehicle fine at times, but often under load, or acceleration, it can produce a misfire.
Three dates is a good rule of thumb.
This isn't a hard and fast rule, but let's say you spend two to three hours together on each date, with some emailing, texting, or phone time in between. That's a pretty fair amount of time together. If you're not feeling any sense of chemistry or attachment, it's OK to give up.
Installing Spark Plugs – Lawn & Garden Equipment
Tighten the spark plug finger-tight until the gasket reaches the cylinder head, then tighten about ½ – ⅔ turn more with a spark plug wrench. (Taper seat: About 1/16 turn more.)
"It's important to give someone a chance as you build the relationship, even if you don't feel that initial pang of chemistry," says Ury. "The right relationship might take some time to warm up, but it'll be worth the wait."