What happens if you drive with bad spark plugs?

Spark plugs are transmitters essential in conveying signals to the combustion chamber. Without a good spark plug, the engine might not start or if it does, the fuel will not burn as it is supposed to be.

Many people underestimate the importance of a ‘healthy’ spark plug. Some people even go as far as using their vehicles without considering the state of this important part.

Sure it is advisable to regularly check on the status of the spark plug, understanding the effect of driving with a bad spark plug is likewise as necessary. This way you will be able to appreciate and commit to maintaining your spark plug.

What happens when your spark plug is worn or malfunctions

Slowed acceleration

Slowed acceleration

A Problematic ignition system is known to cause issues with your acceleration. Computerized car systems can now analyze your car systems including the ignition system and determine where the issue is.

Sensors tell the systems when to send impulses to start the spark plug so a failure with you ignition could be blamed on failed sensors. However more often that naught, a bad spark plug is the issue.

When your spark plug is work out, it will not produce sparks hot enough to ignite the air and fuel combination properly. This reduced effectiveness makes the car slower and decreases its acceleration capabilities.

TIP: Don’t jump the gun and immediately replace your spark plug, rule out any other causes that may have the same poor acceleration effect such as failed sensors, bad fuel filters etc.

Difficulty starting your car

There are many reasons why your vehicle just won’t start. An ignition chamber failure is one of those reasons. As you know, for your engine to start, the fuel and air injected into the ignition chamber must be successfully ignited.

A bad spark plug might produce ineffective sparks or no sparks at all, making it difficult to start your car. Because of this malfunction, the engine will not turn over.

inefficient spark plugs

Engine misfires

Misfires can be very frustrating.  They are caused with incorrect ignition timing, vacuumleaks etc. Apart from being frustrating, misfires can reduce gas mileage and increase you emission. You might even fail your emissions inspection on account of misfires.

They also have a damaging effect on other engine parts. Sometimes, the ignition parts, the spark plug in specific are to blame. As your spark plug begins to wear, it does not perform at maximum capacity and gradually get worse from small intermittent misfires.

Will a misfire hurt your engine?

A worn spark plug is not the only cause of a misfiring engine. There might be other components causing your engine to misfire. If not looked at immediately, you could wind up with internal damage to other components. While driving with a misfiring engine is not immediately dangerous, however as the misfires continue to wear out your components, your vehicle may begin to lose power, which could be dangerous on a busy road.

Poor fuel economy

A functional spark plug can help burn fuel efficiently. When this happens, your fuel economy is optimal. However, when a spark plug is not properly fictional, you cannot burn your fuel properly, therefore you cannot achieve good fuel economy.

It could be that the gap between the plug electrodes is too large or not enough. You can easily remedy this by having your mechanic look at the spark plug and adjust the gap back to the required distance for optimal performance. One sign of poor fuel economy is an increase in fuel consumption

gas prices

TIP: A poorly functioning spark plug is not the only reason for poor fuel economy.

Rough idling

With a bad sparkplug, you might notice your engine sounds quite rough when idling. These rough sounds could even cause yourvehicle to vibrate. This is indicative of a spark plug issue where the cylinder misfires but only when idle.

Consequences of a bad spark plug

Spark plugs don’t just suddenly stop working, the wear and tear gradually decreases their performance until they no longer function or begin to malfunction. Either way, the more inefficient they become, the more you begin to notice the changes we’ve discussed above.

Eventually, you will end up with a reduced gas mileage, sluggish performance, and rough idle if you continue to use your worn spark plug. You are advised to have it checked when necessary for a tune up or a change. Otherwise, continued use of a worn spark plug could end up damaging other components of your vehicle or put you at risk.

Bonus tips on checking your spark plugs

Before you can start either your detailed analysis, you must first identify what a spark plug looks like to begin with. Try checking the internet for what a spark plug in good condition looks like, this way you have an image to reference and compare your plug to.

These checks are basically checking the tip and side electrode to confirm that they are in okay conditions. A blackened top and electrode is an indicator that combustion is not running as it should be and therefore the burning and cleaning processes are disrupted.

Next, you must check the wiring of the plug. With a multimeter, you can check the resistance to see if the wires are running properly. Anything between 10,000 to 15,000 ohms is in the clear. Afterwards, you can check the color of the sparks. Blue sparks are good but yellow sparks mean it may be time to change them.

TIP: While these methods are good for checking the status of your plugs, it is advisable to see your mechanic for a more thorough analysis.

Final word

The spark plug is a small part that plays and important part in proper running of your vehicle. Over time, as the deposits build up or the wear continues, the part begins to influence your vehicles performance. It is important to know the indicators of a bad spark plug and remedy the situation as soon as you can.

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