···
Log in / Register

What Are the Symptoms of Faulty Spark Plugs in Sedans?

4 Answers
MacPiper
07/29/25 9:57am
Spark plug failure manifests in the following ways: Difficulty starting the car, both during cold and warm starts, often requiring multiple attempts. Engine shaking, noticeable while driving. Reduced power output, feeling significantly weaker than usual. Increased fuel consumption. Engine stalling. Failed exhaust emissions. Common causes and diagnosis of spark plug failure: Several factors can prevent spark plugs from functioning properly: Incorrect spark plug gap adjustment. A gap too small limits the spark's contact area with the air-fuel mixture and suppresses flame kernel growth, resulting in weak sparks and ignition difficulties. A gap too large may exceed the ignition system's voltage capacity, preventing sparking. Cracked spark plug skirt. High-voltage current leaks through cracks, preventing sparking at the electrodes. Electrode carbon buildup, causing current leakage from the center electrode instead of jumping to the side electrode. Excessive carbon deposits can short-circuit the plug, damage the insulator, and ruin the spark plug. Electrode damage. Prolonged electrical erosion or chemical corrosion from combustion gases can break or detach electrodes, preventing sparking. Low insulation resistance. This reduces the voltage across the spark gap, weakening or eliminating the spark. High-voltage wire short circuits. Leakage between the ignition coil and distributor prevents all cylinders from starting; leakage between the distributor and spark plug affects only one cylinder. Burnt contact points. This prevents all spark plugs from firing, making the engine unable to start or run. Faulty spark plugs should be replaced promptly. Replacement steps: Open the hood, remove the engine's plastic cover, and detach the high-voltage wires, marking each cylinder's position to avoid confusion. Remove the spark plugs using a spark plug socket, cleaning any external debris like leaves or dust. Insert new spark plugs by hand first, then tighten with the socket. Reattach the high-voltage wires in the correct firing order and replace the cover. Replacement interval: Typically 40,000-60,000 km under normal maintenance, but varies by brand and engine. Refer to the owner's manual for specifics.
Was this review help?
11
4
Share
MacCora
08/13/25 12:09pm
When my car's spark plugs have issues, the symptoms are quite obvious. Starting the engine becomes particularly difficult, and it often fails to ignite after several attempts, which is downright frustrating. While driving, the engine shakes noticeably, especially when waiting at a red light—the steering wheel vibrates so much it makes my hands go numb. Fuel consumption has suddenly skyrocketed; previously, a full tank could last 500 kilometers, but now it's gone after just 400 kilometers—my wallet is crying. The power has weakened too; even climbing a small slope feels strenuous, and the throttle response is sluggish even when floored. Sometimes, there are strange popping sounds from the engine, and the exhaust smells odd, likely due to incomplete combustion. All these issues are caused by aging and carbon buildup on the spark plugs. Not replacing them promptly can damage the engine, leading to even costlier repairs. I recommend checking them every 30,000 to 40,000 kilometers and replacing them—new ones will immediately make the car run smoother and more fuel-efficient.
Was this review help?
1
4
Share
Expand All
EloiseDella
10/07/25 2:01am
Driving with faulty spark plugs is really unpleasant. I usually drive smoothly, but when the spark plugs are bad, the engine shakes and stumbles at low speeds, like it's drunk. Starting the car always takes a few cranks before it fires up, which can be frustrating when you're in a hurry. Acceleration feels weak, and when overtaking, pressing the gas pedal results in a delayed response. Fuel consumption also becomes ridiculously high. Once, after a long trip, I noticed the fuel gauge dropping rapidly and realized something was wrong. At the repair shop, they found that carbon buildup on the spark plugs was causing insufficient ignition, leaving unburned fuel mixture. After replacing them, the car immediately regained its vigor. Remember, regular spark plug maintenance can save you from costly repairs.
Was this review help?
11
1
Share
Expand All
OAliyah
11/20/25 3:24am
It's common for spark plugs to fail after prolonged use of the car. The most annoying issue is difficulty starting the engine, with prolonged cranking but no ignition. During driving, the engine shakes noticeably, especially at idle, causing the car to bump and become unstable. Fuel consumption suddenly increases, power output weakens, and acceleration feels sluggish. The exhaust may emit an unusual odor due to incomplete combustion and poor emissions. It's recommended to replace the spark plugs promptly to prevent damage to other components.
Was this review help?
3
3
Share
Expand All
More Forum Discussions

Where is the central point for left turns in Subject 3?

The central point for left turns in Subject 3 is marked with corresponding signs on the road. Not turning left near the central point of the intersection means that when a motor vehicle makes a left turn at an intersection controlled by traffic signals without turning near the left side of the central point, it constitutes a traffic violation, violating Article 51 of the "Regulations for the Implementation of the Road Traffic Safety Law of the People's Republic of China". Below is an introduction to Subject 3: 1. Definition of Subject 3: Subject 3 includes the road driving skills test and the safe and civilized driving knowledge test, which are part of the motor vehicle driver's license assessment. It is the abbreviation for the road driving skills and safe and civilized driving knowledge test in the motor vehicle driver's examination. The content of the road driving skills test varies for different types of vehicles. 2. Test content of Subject 3: (1) The road driving skills test generally includes: preparation before driving, simulated light test, starting, driving straight, gear shifting operations, changing lanes, parking by the roadside, going straight through intersections, left turns at intersections, right turns at intersections, crossing pedestrian crossings, passing school zones, passing bus stops, meeting vehicles, overtaking, making U-turns, and driving at night. (2) The safe and civilized driving knowledge test generally includes: requirements for safe and civilized driving operations, safe driving knowledge under adverse weather and complex road conditions, emergency handling methods for situations like tire blowouts, and knowledge of post-accident handling procedures.
10
5
Share

What are the dimensions of the Clever?

Its length is 3140mm, width is 1648mm, height is 1521mm (1531mm with shark fin antenna), and the wheelbase is only 2000mm, which is significantly smaller than the already discontinued Roewe E50. The Roewe Clever features a compact body with large headlights, and its side design is quite simple. The Clever's body dimensions are small, positioning it as a microcar. Additional info: The Clever's wheels use basic black steel rims paired with 175/60R13 Cheng Shin CS868 series tires, which enhance the strength of the tread, shoulder, and sidewall.
6
4
Share

How to Reset the Engine Malfunction Light?

The methods to reset the engine malfunction light are: 1. Visit a 4S shop or auto repair shop to use a fault code reader for troubleshooting; 2. Disconnect the negative terminal of the battery to clear the fault codes. The reasons for the engine malfunction light illuminating include: 1. Poor gasoline quality leading to incomplete combustion of the air-fuel mixture in the cylinders, resulting in carbon deposits; 2. Excessive mileage causing weakened spark plug performance; 3. Aging vehicle components; 4. Damaged, poorly connected, or interrupted signals from sensors such as coolant temperature, crankshaft position, air flow, intake temperature, and oxygen sensors. Solutions for the engine malfunction light include: 1. Promptly inspect the engine's condition; 2. Check the status of sensors, air flow sensors, and spark plugs; 3. Check for engine knocking; 4. Inspect the ignition coils for faults; 5. Clean carbon deposits from the engine.
3
2
Share

Why are used Roewe RX5 so cheap?

Roewe RX5 used cars are inexpensive for the following reasons: Resale value: The main reason is that Roewe RX5 has a low resale value, so when sold as a used car, the price is relatively low. Factors contributing to the low resale value include the small market share of the vehicle and relatively high maintenance costs. Before reaching scrap standards: If a car has not yet reached the national scrap standards or can still be used during its economic lifespan, it can be traded as a used car. Choosing to buy a used car is also a wise decision. With the continuous development of the automotive industry, the performance of cars is constantly improving, and vehicle emissions can be gradually reduced. By implementing vehicle emission standards, atmospheric pollutants emitted by cars can be directly reduced at the source.
10
0
Share

What voice command to open in Nissan cars?

Nissan's latest smartphone integration system supports Apple iOS CarPlay functionality. After connecting via a data cable, you can use the steering wheel buttons to activate the voice command Siri for hands-free calling and quick navigation planning. It also supports most mainstream Android smartphones on the market, enabling connection via Wi-Fi + Bluetooth. Stay connected to information both inside and outside the vehicle without holding your phone. Here's the relevant introduction: Function of in-car voice assistant: During daily driving, it's inevitable to perform some simple operations such as turning on the air conditioning or activating navigation. With the rapid development of in-car voice assistants, these simple operations can now be handled by the voice assistant, significantly reducing distraction time while driving and improving driving safety.
11
3
Share

What are the reasons for the Highlander's Bluetooth connection failure?

Highlander's Bluetooth connection failure may be caused by the following reasons: Mobile device issues: It is recommended to clear the information of the paired device, then click to scan for devices, locate the device to be connected, and proceed with the connection. There will be a verification process during this time; simply follow the prompts. Issues with the Bluetooth device being connected by the phone: For Bluetooth devices such as headphones, it is advised to check if the battery is sufficient and restart the device before trying again. If it still doesn't work, you can perform a factory reset. The method to reset varies by device, so refer to the manual or consult customer service. Location issues: There may be interference from other Bluetooth devices nearby. It is recommended to try connecting in a different location.
8
4
Share
Cookie
Cookie Settings
© 2025 Servanan International Pte. Ltd.