How can you tell a bad spark plug?

What happens when a spark plug goes bad?

Worn out spark plugs can increase your vehicle's fuel consumption because they won't effectively burn the fuel that goes into the engine, meaning you'll be shelling out more money on fill-ups.

How do you know if you need a new spark plug?

What does a failing spark plug sound like?

Sometimes, especially while accelerating, you will hear your engine making a distinct knocking sound. That sound is caused by your spark plugs not detonating properly and igniting all the fuel. The fuel and vapor that did not ignite eventually will catch fire and detonate.

What does a weak spark look like?

A good spark will be blue-white and will be plainly visible in daylight. If a good spark is present, the problem is probably not in the ignition system. Check the fuel system and/or stark timing. Weak sparks are orange or red and may be hard to see in daylight.

How to "Read" your Spark Plugs | Goss' Garage

What happens when one spark plug is not firing?

A single spark plug that fails to ignite the fuel-air mixture can cause a halt in the running of the engine. It can result in incomplete combustion and damage to the catalytic converter of the car. Faulty spark plugs can cause the car to exhibit starting troubles.

What should good spark plugs look like?

A normal spark plug will have brown or grayish-tan deposits on the side electrode. Everything is just fine with your spark plug; you can reinstall the spark plug.

What does a brown spark plug mean?

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.

What do black spark plugs mean?

Black spark plugs are a sign of a weak spark or too much fuel in the air-fuel mixture.

What does an oil fouled spark plug look like?

Oil fouling of a spark plug typically results in a shiny, black appearance. If enough oil is in the combustion chamber, the deposits can build up on the tip, porcelain or shell. If you can't determine if it is carbon or oil fouling, smell the plug; it will smell like engine oil.

What does a spark plug misfire feel like?

Misfires can happen when a vehicle is under load while accelerating. This causes slow or sluggish acceleration and your vehicle may have trouble getting up to speed. You might feel a jerking motion when pressing down on the throttle. The most common cause of an engine misfire when accelerating is worn-out spark plugs.

How do I know if my ignition coil is weak?

The only safe way to test for spark is to use a spark plug tester tool. If a coil problem is suspected, measure the coil's primary and secondary resistance with an ohmmeter. If either is out of specifications, the coil needs to be replaced.

What does a red colored spark plug mean?

However, don't be dismayed if ceramic insulator tips (center and ground electrodes on a plug) are pinkish-red in color. That pink coloration is created by deposits from additives in unleaded fuel when they're burned off during combustion.

What causes a weak spark at the spark plug?

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.

Can a weak spark cause a misfire?

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.

Will changing spark plugs fix misfiring?

If your engine is misfiring, you may be able to fix the problem easily by replacing your spark plugs. Spark plugs are relatively easy to remove from engines and inspect for damage, and at less than $25 a piece, they are relatively cheap to replace, too.

Can you drive with misfiring spark plugs?

An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn't safe and can damage your engine.

How can I tell if my engine is misfiring?

What happens if you have oil in your spark plugs?

Oil making its way into the spark plug wells will drastically affect the engines performance, leading to misfires, increased oil consumption and blue exhaust. In extreme cases, it can even lead to an engine fire. If the vehicle is exhibiting any of these symptoms, the spark plugs should be inspected immediately.

What does white spark plugs mean?

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.

Why are my spark plugs black and sooty?

Soft, black, sooty dry deposits on plug indicate carbon fouling. Carbon fouling is an indication of a rich air-fuel mixture, weak ignition, or improper heat range (too cold). Carbon deposits are conductive and can create a path for spark plug misfire.