“Car runs worse after changing spark plugs” can happen if the new plugs are improperly gapped, installed, or not compatible with the vehicle. Additionally, issues like old ignition coils, dirty fuel injectors, or incorrect spark plug wiring can also cause performance problems after a spark plug replacement.
In your mind, what your car will closely feel like once you change its spark plugs contains smoother shifts, smoother “drive-by-wire” inputs, and better acceleration and throttle response. After all, spark plugs are specifically designed to play very important role in an engine’s performance. But what if, after changing the spark plugs, the engine performance deteriorated? Instead of smoother acceleration, you might experience rough idling, hesitation, or economical use of fuel.
This unknown phenomenon is the focus of this blog post. No matter whether you are a beginner or someone with some experience in DIY car ‘s maintenance, this guide will offer you the reasonable causes, addressed in the next section, along with the steps to rectifying the spark plug problem.
Contents
- 1 Why Car Runs Worse After Changing Spark Plugs
- 2 Function of Spark Plugs in Vehicles
- 3 Common Reasons Car Runs Worse After Changing Spark Plugs
- 4 Step by Step Guidelines on Troubeshooting for Newcomers
- 5 Frequently Asked Questions
- 6 Final thoughts
Why Car Runs Worse After Changing Spark Plugs
In the wake of changing spark plugs, the performance of your car will sink to new lows than anticipated thanks to a plethora of reasons that could be arising. this could be failing to or improperly connecting a wire connection and assuming there are no other faults otherwise in the ignition fuel or other components.
In the following section, we will explore the most common reasons that could be the root cause to these issues.
Function of Spark Plugs in Vehicles
Although quite small, spark plugs play a very important role in a car’s engine. Every time the engine fires, the spark plugs creates the necessary spark to ignite the fuel which, in turn, along with air multiplies, releases the energy to power the engine.
In the event that a spark plug fails to operate correctly, or within the parameters of the malfunctioning spark plug, the vehicle in which the spark plug is placed is likely to have the following problems:
- Rough idle
- Poor fuel efficiency
- Most engine hesitations or even stalling
- Total loss of power
In an ideal world, simply replacing the old plugs with new ones should solve all of the issues listed above. On the contrary, in a real world, with even an underperforming engine, most problems arise because of the very reasons which have already been established.
Common Reasons Car Runs Worse After Changing Spark Plugs
Even if the spark plugs are replaced, you should have no issues with the engine or the overall performance. Sadly, you put them in and you are bound to encounter problems. This section is aimed to help solve the most common problems that arise, in order to help your vehicle preform, instead of the opposite.
1. Gaps Are Not Set To Spark Plugs
Poor performance can be a result from a plethora of elements. In the context of the last chapter, we mentioned the Spark Plugs gap. It is important pysically understand what the gap is. The Spark Plug is made of two electrodes. The gap is the distance between the anode and the cathode. If this distance is too much or too little, it will disturb the flush.
Too much distance: If there is too much space, the energy available will not be enough to cause ignition.
Too little gap: If there is too little space, the energy will cause a ignition and will cause malfunction and problem of an repeated start.
Consequences of Incorrect Spark Plug Gap:
- Bad engine start
- Repeated start
- Loss of speed
- Shooting noise
Remedy: It is important While installing new Spark Plugs to use a feeler gauge to check the gap. The owner’s manual or the spark plug box will specify the gap. The gap needs to be set to what your car model recommends.
2. Incorrect Type of Spark Plug
Not all spark plugs are alike. Different vehicles need different types of spark plugs which vary in heat range, electrode materials such as copper, platinum, iridium, and thread length. Spark plugs that are mismatched, although they may fit, will not work to your vehicle’s best ability.
For example:
Heat range: Spark plugs of differing ranges, too hot or too cold, will cause issues. A spark plug that’s too hot will likely over heat, leading down the detonation or pre-ignition road. A cold plug leads to fouling and misfires.
Material type: While platinum and iridium spark plugs are tougher and more effective, copper plugs are inefficient and underwhelming.
Symptoms of Incorrect Spark Plug Type:
- Engines misfire
- Reduced gas mileage
- Vehicle shaking
- Check engine light
What to do: Use the specified spark plug type for your vehicle. If you want to know the most effective method, consult your owner’s manual or a trained technician for help. It’s vital that you do not confuse the spark plug materials and ranges of your engine.
3. Wrong Installation Steps
Even though installing spark plugs seems trivial, most people tend to mess it up, which is one of the main reasons behind performance issues after changing spark plugs. Any spark plugs can get damaged if the installation is carried out without the right torque, or are over-tightened or under-tightened.
Over-tightening: When spark plugs are over-tightened, the threads in the cylinder head or the spark plug can get head damaged, which creates the opportunity for connections to get poor and misfires to occur.
Under-tightening: If plugs are incorrectly fitted into the engine, plugs can similarly result in a loose, along with an engine functioning erratically and total spark failure.
Wrong Installation Steps also includes the destruction of any of the spark plugs wherein the electrode or the ceramic insulator are damaged, resulting in failure to operate spark plugs.
Symptoms of Improper Installation:
- Engine power loss
- Rough engine idle
- Misfires
What to do: Aside from the installation steps which specifically mention any installment without the right torque or using excessive force to the thread alignment, there are also steps which mention using a torque wrench to tighten the plugs to pre, along with post-installation steps.
4. Defective Ignition Coils or Wires
In case you swapped the spark plugs and the condition of your car worsened, then chances are the issue lies not at the plugs, but rather within the ignition systems like coils or wires. Ignition coils are the ones to deliver electrical stored currents to the spark plugs. If the coils are faulty, the spark plugs can either misfire, or not fire at all.
Signs of Defective Ignition Coils or Wires:
- Engine misfires
- Harsh engine idle
- Reduced power and acceleration
- Increased fuel consumption
What to do: Ignition coils and wires should be the first systems checked. If the wires are frayed or cracked, do not hesitate to replace them. The coils should also be checked and any that are deemed broken ought to be replaced in order to restore proper engine performance.
5. Problems with Fuel System
In some case, the issue at hand might actually be with the fuel systems instead of the spark plugs. For example, faulty fuel injectors or a blocked fuel filter can interrupt the fuel flow to the engine which can in turn lead to poor combustion and a rough running engine. These issues can surface when you change the spark plugs.
Signs and symptoms of fuel system issues:
- Stalling of the vehicle and engine ‘hesitation’
- Achieving speed and ‘accelerating’ becomes difficult
- Lowering the fuel efficiency while driving
- Failures of the engine and ‘engine misfiring’
What should be done is checking the fuel injectors and unclogging them if they are clogged. Replace the fuel filter if it is clogged. If you are unable to judge the fuel system condition, perhaps visiting a mechanic would help. A mechanic would help you with a fuel system check.
6. Uncovered Issues Being Exposed
In some cases, changing the spark plug doesn’t worsen the performance of the vehicle, but it may, in fact, uncover an existing issue. A vehicle may have an “okay” performance with old spark plugs if there is a damaged air intake, a vacuum rupture, or a clogged sensor, but, once spark plugs are changed, the issues become more observable.
Signs of Uncovered Problems:
- Engine is “misfiring,”
- Rough “idling” of the vehicle
- ‘Accelerating’ becomes difficult
- Loss of power
What must be done is an exhaustive diagnostic of the air intake system, sensors and vacuum pipelines of your vehicle. If you are not experienced in these areas, a mechanic should be able to diagnose and fix the issues.
Step by Step Guidelines on Troubeshooting for Newcomers
Following are the steps to troubleshoot if the cars function is deteriorating after changing the spark plugs:
Check the Spark Plug Positions: Use a feeler gauge to check that the gap is set correctly; you can refer the vehicles manual or even google doesn’t help you much. Even a gap little too much or a little too less can lead to huge issues with your car.
Type the Spark Plug Check: Installing the wrong type of the spark plug is easy. Look up the part in your car manual or do a simple online check based of the type of your car.
Check the Method of Plug Setup: The spark plugs and installations should not be crossed. Make sure all the plugs have actually been fitted and are not loose. Make the needed adjustments and check if any of the wires and plugs are damaged.
Check the Coils and Ignition Wires: Make sure that the ignition wires and coils are not worn out or have any cracks. for any broken wires just throw them and replace.
Inspects the System: The fuel injector and fuel filter can also be clogged. If clogged make sure you replace them with a new one and clean.
Check for any Codes in the System: Use the OBD2 to scan and check for any codes if found. Then resolve the issue as per the code.
Test driving and evaluating: After the modifications have been made, take the car for a test drive and see if the issue still exists. Hold back the yawns and take note of anything that sounds like misfires, engine hesitation, or anything that sounds like a rough nap.
Frequently Asked Questions
Here are some FAQs about car runs worse after changing spark plugs –
Q1: My car engine runs worse after changing the spark plugs, can I just reinstall old spark plugs?
A1: The old plugs might be reinstalled to restore the very same behavior, but that is a wrong approach to take. More often than not, the issue lies in the way the installation was done, or the spark plugs doesn’t match. Every effort should be made to pinpoint the issue.
Q2: How do I know if the spark plug gap is correct?
A2: The gap can be measured and checked using a feeler gauge. The original measurement should be compared to the documentation that comes with the car, as well as to the box the spark plugs came in.
Q3: What happens if I use a spark plug type that is wrong?
A3: The instant effect is engine misfires. Followed immediately by poor acceleration, rough idling, and anything that is in the ballpark of reduced car performance. It is critical to use the spark plug that fits the vehicle the most.
Q4: Are there other problems with my car that were uncovered while changing the spark plugs?
A4: Changing spark plugs can sometimes reveal other problems with the ignition system, fuel system, or sensors that were hidden, due to other worn out parts, which are much more cheaper, that were protecting the system.
Q5: With the spark plugs, should I change the ignition coils, too?
A5: Yes, changing the spark plugs should help the car perform better. If the car does not perform that means there are other problems. Identify where there are spark plugs which means ignition coils have enough space in the car.
Final thoughts
If the spark plugs were changed and the ignition system deteriorated, the ignition system is much more cheaper. Look for fast solutions. If replacing everything, maintain the order in which everything is taken out so it can be installed in the exact order.
The car can cope better in these days with the right knowledge and minor changes, and in turn can perform better with the fuel. With rest, do not take the front spark plugs out, perm. If the parts are not available, replace them with something. If no improvement is there, there is no harm in going to a mechanic.
