A car engine misfire can have a significant impact on your driving experience and, more importantly, on the life of your vehicle. But what causes a car to misfire?
The term refers to the condition when one or more of the engine cylinders fails to ignite the passing air fuel mixture in a properly synchronized way with the other cylinders.
When a car causes to misfire, each affected cylinder is not delivering power as it should make the vehicle feel as if it is jerking or surging. This causes it to run unevenly and roughly. The causes of engine misfires can be numerous and multifaceted, as complex as any machine’s normal operation.
Diagnosing a misfire can be difficult, but it is absolutely crucial to attempt to identify it and to treat it, as a misfire can spell disaster for the life of the engine. In this article we will look at what causes a car to misfire and how to fix the issue.
Article Summary
What is Car Engine Misfire?
A car engine misfire is a problem with the engine that leads to some of the cylinders not combusting their air fuel mixture normally. This will cause what is called an engine miss or jolt or jitter, which can normally be felt. It normally does not feel good.
A cylinder misfiring does not usually complete the combustion or detonation process of the air fuel mixture. In other words, the spark or electrical current fails to do its job correctly on a cylinder’s stroke. While this will not destroy the engine, it can eventually cause it to fail.
The cylinder fails to contribute nearly 100% of its share of engine torque. Many things can cause an engine cylinder to misfire.
A car engine misfire will result in numerous problems, such as poor acceleration, poor fuel economy, a rough idle, tissue paper like power, and damage to the catalytic converter due to unburned hydrocarbon gases escaping the exhaust system.
The spark plugs or ignition coils, the valve train or camshafts, the fuel system or fuel injectors, or turbos can all fail or malfunction and cause a cylinder misfire.
Whatever the root cause, the number one law in engine misfires is: “If you hear it, if you feel it, then fix it”.
What Causes A Car To Misfire?
An engine misfire can be a frustrating problem, characterized by a noticeable loss of performance, a rough idle, or a jolting, shaking feeling while driving.
Various common causes could be attributed to an engine misfire, and figuring out what’s causing your vehicle to work improperly is an important step to take when troubleshooting this issue. Here’s what might be going on under the hood.
1. Faulty Spark Plugs
The function of spark plugs is vital and ensues by producing a spark in the combustion chamber of the engine that ignites the air fuel mixture and initiates the combustion process.
However, if this process is providing enough power to the engine, there’s the possibility that the spark plugs are worn out or fouled. Signs of such failure include reduced acceleration, high fuel consumption, and starting difficulty.
Replacement of spark plugs can be performed during regular maintenance service and on time to prevent misfires.
2. Ignition Coil Problems
The ignition coil generates the high voltage necessary to cause the rapid oxidation that ignites the fuel air combination.
When an ignition coil fails, it can produce lower voltage than usual, which might cause thin, weak sparks in the spark plugs of your engine.
This is likely to generate misfiring of the engine. So, if you have noticed a drop in engine power or your car has been idling roughly, a faulty ignition coil is one possibility.
3. Fuel Injector Issues
On the way there, they are fired inside the combustion chamber, where they mix with the right quantity of air and keep the engine alive.
If a fuel injector clogs or doesn’t work properly, the engine could end up with too much fuel or not enough, leading to ignition in the wrong place.
These are the symptoms of a fuel injector problem: decrease of mil, decreased running, rough running of the problem, and starting problems.
4. Air Intake Problems
The engine’s proper function depends upon the optimal air fuel ratio. Any imbalance in the system disrupts that ratio for example, a dirty or clogged air filter increases resistance to the air intake system, leading to misfires, poor engine performance, and higher emissions.
5. Vacuum Leaks
When a section of your engine’s vacuum system allows unmanaged air to enter the engine, it’s considered a vacuum leak.
Excess air can throw the stoichiometry of the burnt air fuel mixture out of balance, causing misfires and a rough idle. Vacuum leaks often present with an audible hissing sound and erratically wild engine RPM.
6. Fuel Pump Failures
The Fuel pump is the part that feeds fuel to the engine from the tank. If it stops working or gets weak, it can lead to low Fuel pressure, which in turn causes misfiring and power loss from the engine.
Symptoms of a failing fuel pump include stalling, difficulty starting the engine, and loss of power from accelerating.
7. Engine Timing Issues
The opening and closing of the engine’s valves must be timed to coincide with the pistons’ movements. Otherwise, the engine will misfire and run poorly. Timing problems generally relate to a broken timing belt or chain and require professional repair.
8. Sensor Failures
The engine has many sensors (oxygen sensor and mass airflow sensor, to mention a few) that send critical information to the ECU.
An ECU that receives faulty information from its sensors might adjust for incorrect parameters in the air fuel mixture, causing misfires.
This will result in a check engine light activating as well as a larger array of symptoms for the car, including changing engine performance.
9. Engine Compression Issues
Engine compression, a crucial part of the combustion process, is maintained in all cylinders to acceptable but minimal levels.
Signs of low compression include rough running, stalling, misfiring, a drop in power when driven, and possible oil burning on the exhaust pipe.
Low engine compression can be caused by worn or damaged piston rings, a warped cylinder wall, or a blown head gasket.
10. Faulty Wiring or Connectors
Breaks in the wiring or fraying, as well as loose electrical connections to components such as the coils or fuel injectors, will show up as misfires. Check both periodically for wear and damage.
How To Address A Misfire
Diagnostic Testing: A diagnostic tool such as an OBD-II scanner can run diagnostics and determine which cylinder is misfiring and why.
Check for Wear or Damage and Replace Parts: Check spark plugs, ignition coils, and other fuel system parts for wear and damage. Replace defective parts.
Check for Leaks: Check all the vacuum hoses and your intake manifold for leaks. Repair any leaks you find.
Refer to a Specialist: If you are unsure if you can resolve the issue yourself or if you can handle the repairs, you should consult specialist mechanics.
How To Fix A Car Misfire?
Fixing a car engine misfire involves a few key steps:
Run A Diagnostic Test
Use an OBD-II scanner to identify misfire codes. This can tell you which cylinder they relate to and help you focus your refinement efforts.
Inspect and Replace Spark Plugs
Inspect the spark plugs for wear or damage. Replace them if worn or damaged. Replace with the proper gap.
Check Ignition Coils
Check the ignition coils for operation. If any are faulty, replace them. They provide the spark to cause the fuel to combust.
Check Fuel System Components
Inspect the fuel system components, including injectors to see if they are plugged. Ensure that the fuel filter is not blocked. Clean or replace these parts as needed to restore fuel saturation.
Inspect Air Intake and Vacuum Hoses
Make sure the air intake and vacuum hoses do not have any cracks or leaks. This is vital because it can affect the air fuel mixture in your car.
Check Engine Timing
Timing! Your engine’s automatic ignition should occur when the piston is at the top. The timing can get out of whack and cause your car to run rough.
Find a professional to check and adjust your timing as needed. If this doesn’t solve the misfire, get the car checked out by a mechanic who can trace all the issues and put it back together.
How To Prevent A Car Engine Misfire
To prevent engine misfires, consider these measures:
Regular Maintenance: Your vehicle’s maintenance schedule delineates the base ignition coil, spark plug, and air and fuel system cleanliness requirements. This maintenance keeps the ignition and fuel system current.
Fuel System Care: Use well-refined fuel to keep fuel clean and flowing freely (after all, it’s called well-refined for a reason). Follow the manual’s recommendation for replacing the fuel filter (clogging can reduce compression and cause overheating) and clean the fuel injectors regularly.
Inspect For Leaks: Check for cracks and tears in the air intake and vacuum hoses regularly and replace damaged ones. Leaks in the vacuum system decrease the amount of fuel entering the air, throwing off the air fuel mixture and causing misfires.
Sensor Monitoring: Watch your engine sensors (e.g., the oxygen sensor or the mass airflow sensor). Address those right away. They control the air fuel mixture and are critical to effective engine function.
FAQs on What Causes A Car To Misfire
What Are the Signs of A Car Misfire?
Signs of a car with a misfiring engine include rough idling, hesitation during acceleration, a noticeable loss of power, reduced fuel economy, abnormal engine vibrations (shaking), and a check engine light in the dash.
What Causes A Car To Misfire?
There are several reasons why the car engine would misfire, such as a faulty spark plug, bad ignition coil, blockage of the fuel injector, air intake problems, vacuum leak, engine timing problems, or any sensor based issue.
How Can I Diagnose A Misfire in My Car?
It’s usually a good idea to begin investigating a misfire by checking for error codes with an OBD-II scan tool, followed by checking spark plugs and ignition coils and then testing the fuel system and air intake components. A trained automotive technician might use one or more of these methods but is also likely to pursue a more thorough diagnosis.
Can A Misfire Cause Long-term Damage To My Engine?
If left untreated, more permanent damage may occur, resulting in decreased fuel economy and increased emissions. The misfiring engine may also put increased strain on other engine components. Over time, these parts may also need to be repaired or replaced, sometimes at great cost.
How Can I Prevent Engine Misfires?
Keeping the engine running smoothly will reduce the risk of misfires. Simply replacing spark plugs, ignition coils, and air filters when needed and having a clean fuel system will minimize the risk of misfiring. The presence of a vacuum leak from the air intake or other issues should be addressed as soon as possible to prevent the potential of misfiring.
Conclusion
A misfire needs to be treated by identifying and fixing the underlying problem. If you tend to your engine regularly and carry out repairs at the appropriate time, misfires can be prevented, and you can keep your engine running smoothly every time it starts.
If your car continues to suffer from misfires repeatedly, you should consider consulting with a mechanic to determine and correct the cause of the problem.
