If the spark plug has a blackish build-up around it, you need to check the engine immediately. Symptoms indicate that the plug is weak or your fuel mixture is too rich, which results in slowing down and misfiring. It could also be created by a bad O2 sensor called the ECU.
A black plug indicates an over-rich mixture of fuel and air. The most likely cause is a clogged air filter. While it looks black and oily, the car engine will be ragged and burning oil, probably with blue smoke at times from the exhaust.
It might be a fuel injector issue or a sensor problem if there are oxygen sensors.
Why Are Spark Plugs Black? There Are Lots Of Possibilities
The dark setting of plugs is an indication of something wrong in the engine. Let’s see what those can be:
- Failure of compression (due to valves, rings, and piston)
- Fuel injector problems
- Rich Air-fuel mixture
- Carburetor problems
- Air intake problems
- Spark Plug itself is faulty
- Timing error
- Battery problems
- Weak spark due to bad wiring
Materials Required to clean black spark plugs:
- Small soft brush
- Spark plug gap tool
- Spark plug wrench
- knife to scrape
- Rubbing alcohol
How to Clean Black Spark Plugs?
Detergent can remove rust and soot if there’s any. Then with rubbing alcohol, flood the tip of the black plug and let it sit for one minute. Then scrub it with a small soft brass or plastic brush.
Spark plugs should be cleaned with a wire brush or spray-on cleaner made especially for this.
Add more cleansers as needed and clean as deeply as possible in and around the tip. With clean rugs, wipe the spark plugs dry after washing. You also apply a strong knife to scrape off the tough black stain.
Caution: NEVER use a shot blaster, sandpaper, or abrasives to clean a black or brown spark plug.
What Color Should Spark Plugs Be?
A gray or light tan is the normal color of the plug, but when a different hue is spotted, it’s a red flag, obviously.
Can Bad Spark Plugs Cause Black Smoke?
The situation should be taken seriously when the black smoke persists after the car has warmed up. If the problems arise, it indicates that the car’s fuel ratio is off and burning too much fuel than it should.
Replacing spark plugs is one of the most cost-effective car maintenance tasks. But the damage they can cause when worn is among the most costly. Because of this, it’s important to regularly service your spark plugs and understand how to interpret their condition.
Blackening on one side only is most likely caused by valve burn-out. Basically, clogging occurs from the bottom to the side electrode of the spark plug (not to the center electrode).
Greetings from James Milan. I am an Automotive enthusiast and car repairing expert for over 12 years. Blogging is one of my hobbies. According to my interest, I’ve started this blog to share my thoughts about the Automotive sectors and hope you’ll love it.