mechanic working on the car exhaust

Can a Bad Car Battery Cause a Misfire? [And How to Fix It!]

When you get in your car and start it, you may sometimes hear the engine struggling to turn over and start idling quite smoothly initially. Only for the exhaust to sound off every few meters whenever you are accelerating, your engine is backfiring while also struggling to start.

A bad battery will cause your engine to backfire, especially once a heavy load is applied, with the spark plugs not receiving enough amps to spark on time. The battery will need to provide the initial power when accelerating, making a healthy alternator useless when the battery has failed.

There is more to know about car batteries than simply connecting them; learning how to test them and when will take you a long way. We recommend that you learn how to properly know when the battery is bad and fix the car when things start going wrong.

How To Fix A Bad Battery Causing A Misfire?

The first part of knowing how to fix the car when a bad battery is causing a misfire will involve testing different components. A brand-new battery can become bad within a few days if the engine’s overall health is not what it should be.

You might have heard some people claiming they bought three new batteries without their car consistently working. Three things work together to get the car moving and to keep it going; each one can be the cause of both a misfire and a bad battery.

Test The Health And Voltage Of The Battery

Voltage is the first thing you should test, as even a battery that has a voltage too low to start the car may not trigger the battery warning light. Further, many batteries can start the engine but will only start failing when having to accelerate.

We recommend buying a battery tester on Amazon that will tell you how much voltage and amperage the battery has. You need to compare these numbers to the numbers on the battery itself; even an older battery should still deliver top-end voltages and amperages.

Test The Starter Motor And The Spark Plugs

If you have replaced the battery recently, but the misfires are still happening, you need to check the starter motor and the spark plugs on your car. Hopefully, the starter motor needs to be replaced, and some of the spark plugs are getting older and need to be replaced.

In the worst case, you may see that the spark is happening at the wrong moment on each spark plug, this will be a much trickier problem, and we recommend handing the car over to a mechanic. Fixing timing issues requires special tools and some training to fix properly.

Check The Voltage Coming In From The Alternator

The last thing you will need to test is the incoming voltage from the alternator; this is usually the car’s main component that causes bad batteries to propagate. As the power that should be used to recharge the battery is too low, it will fail and can even fail while you are driving.

Alternators can be tricky to fix; sometimes, all you need to do is replace the timing belt with one that works properly. However, there are other times you may need to get a new alternator, which can be tricky and should only be done by mechanics on modern, technologically advanced cars.

Replace The Broken Components

If it is not your car’s battery that is bad, then you will need to fix and replace the other broken components. Whether this is the starter motor, alternator, spark plugs, or alternator, it may even be a component that drains too much power while the car is powered on.

We always recommend replacing the battery after four years if it has been drained to completely flat. New car batteries can usually handle being completely drained, but as the batteries get older, being drained completely can severely damage them, causing permanent unrepairable damage.

Recharge The Battery

If you bought a new battery recently and you are sure that everything has been fixed, then you need to recharge the battery in one of two ways. You can jumpstart the vehicle and go for a drive for longer than an hour, or you can hook up a battery charger that gets power from a wall socket.

We recommend using a wall charger for the battery as this is the surest way to get the battery fully charged and ready. Further, you won’t have to risk the car dying while driving around; we recommend the Schumacher SC1281 on Amazon; it is affordable and also plug and leave.

Can A Weak Battery Cause A Car To Run Rough?

With almost all cars, the engine will start to misfire when the battery can no longer provide consistent power. While the engine may be fine when sitting and idling, it will inevitably start misfiring once you accelerate.

Many assume that once a car has started, the alternator will start providing all the power required to get the engine going. However, this is only true on significantly larger engines, as they have alternators that could usually power a small house without a problem.

In normal sedans, hatchbacks, and small SUVs, the battery provides almost all the power the engine needs. With the alternator just working to recharge the battery and almost nothing else, a bad battery will cause the engine to run particularly rough.

Can A Bad Battery Cause Weak Spark?

A bad battery will cause a weak spark on the spark plugs or even no spark to occur, even when the engine is fully running. While this is unlikely to happen on a new or freshly serviced engine, most engines that have been used will have the gap in their spark plugs grown, causing weaker sparks.

It should be noted that diesel engines do not have this problem, and once the engine has reached operating temperatures, the battery no longer keeps the engine going. This is because they use glow plugs that are kept warm by the engine’s internal combustion process.

Often you will find that bad batteries are a sign of larger problems in the car, with many owners erroneously not looking into the deeper issues. Having the other engine components checked whenever your battery fails will ensure a good overall experience.

Does A Bad Battery Affect The Spark Plugs?

Car spark plugs and wires on the table closeup, nobody, motor diagnostic. Car with opened hood on background, auto-service

Yes, the bad battery will affect the spark plugs in your car, with most spark plugs failing to spark or even sparking late. This happens because the battery cannot provide the required voltage for the spark, with late sparks. After all, the voltage builds up and is released at the wrong time.

Often, bad batteries will also cause backfires to start happening when you accelerate in your car, which makes it extremely uncomfortable to drive the car. Combined with misfires, you will be causing internal damage to the engine as gasses and liquids start to build up drastically.

We always recommend that people fix the problems as fast as possible, as driving for long periods with a bad battery will cause more damage down the line. Replacing a bad battery is significantly more affordable than replacing a piston because of buildup.

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