Car is misfiring

My local Mazda dealership mechanics couldn't figure this problem out. I've been experiencing misfires on the #3 cylinder for a couple years now. While the car was still under warranty, they would just replace spark plugs and coils, then the car would be fine for a time. I think the last year it was under warranty, I had it in 4 times for the exact same issue. They eventually swapped the #3 coil and plug with one of the other 3 in the car and the misfires continued on #3. Then they replaced the air intake, but it still happened again. The check engine light came on and #3 cylinder misfi
Experienced mechanics share their insights in answering this question :
It sounds to me like you have a wire connector issue with the ignition coil pins. The male and female sides fit too loose and only make partial contact. After driving a while a small amount of corrosion forms in the connection and causes the misfire. As soon as you disconnect and reconnect it the connection was made again so it would work for a while. The coil may have failed due to excessive resistance from the corrosion in the connector, and this is most likely what has happened now. I suggest you have the vehicle scanned again. If the failure was #3, then replace the coil and connector. You should also try and put stabilant 22 in all the coil connectors before reconnecting them. The stabilant 22 will stop any corrosion and help keep a full connection. A certified mechanic from YourMechanic can inspect your misfiring issue at your home or office.

How to Identify and Fix Common car Problems ?

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Common reasons for this to happen:

Faulty spark plugs or wires. Faulty ignition coil. Broken piston rings.

A malfunctioning ignition coil will cause your vehicle to misfire when you accelerate. In extreme cases, a misfire could cause your vehicle to shut down while you are driving. The misfire is a result of one of the cylinders fires incorrectly or not at all.
Sporty, speedy and easy on the eyes, your Mazda6 has all the makings of a masterful, yet functional, little sports car. See that its spark plugs get plenty of power by replacing that old, worn-out ignition coil with a new, custom Mazda6 ignition coil from AutoZone.
The most common causes of misfires are worn, improperly installed, and mishandled spark plugs, malfunctioning ignition coils, carbon tracking, faulty spark plug wires and vacuum leaks.
If left untreated, a cylinder misfire can lead to significant engine damage. Worse, if you experience a bad misfire while driving, it could result in an accident. This is why it`s important to treat engine misfires as soon as you detect them.
Once the engine is cranked, you should look for blue sparks along the spark plug gap. If you can see blue sparks, this proves your ignition coil is working correctly. If you don`t see blue sparks or you see orange sparks, this is a sign that there`s a problem with your ignition coil.
If the combustion cycle isn`t running smoothly, the engine won`t be as powerful and you`ll notice the difference in performance. If you notice that you`re stalling more frequently, or that the engine is sluggish when you press the gas pedal, it`s a good idea to get the ignition coil checked out.
The ignition coil on your car is supposed to last around 100,000 miles or more. There are a number of factors that can lead to this part become damaged prematurely. Most of the newer cars on the market have a hard plastic cover that is designed to protect the coil from damage.
The best part is, our Mazda 6 Ignition Coil products start from as little as $36.24.
While it is possible to drive with a faulty ignition coil in many cases, doing so for extended periods of time is never advised. An engine in this state will run at less than peak efficiency, often leading to intermittent stalling or starting difficulties.
Code P0351 is defined as “Ignition Coil `A` Primary/Secondary Circuit Malfunction.” It`s an OBD-II diagnostic trouble code (DTC) that indicates a fault with ignition coil `A` (a problem with the coil on cylinder #1 or its circuit).
To test for voltage output, connect a spark tester to the high-tension output terminal of the ignition coil. Then, crank the engine and observe the spark tester. If the spark is strong and consistent, the ignition coil is functioning correctly. However, if there`s no spark or a weak spark, the ignition coil is faulty.
Yes. While the damage may seem small initially, the longer you drive with a bad oxygen sensor, the worse the damage will become. Eventually, you may experience rough idling, poor acceleration, engine misfires, an illuminated check engine light, and failed emission tests.
Repairing a misfiring engine can be simple or complicated, depending on the reason it is misfiring. The most common causes of engine misfires are: worn spark plugs, weak fuel injector, vacuum leak, worn valve seals, carbon tracking, and no voltage at the coil.
The engine misfires. Once a timing chain is stretched and has lost its integrity, the chain may skip a gear and lose the necessary coordination leading to an engine misfire. Repeated misfires could indicate a timing chain issue and should be investigated.
What kills ignition coils is location; being mounted in one of the hottest, most vibration prone and dirtiest parts of the engine. Modern ignition coils are typically located between two camshafts on the valve cover and exposed to dirt and oil.
If an ignition coil is not working properly, your engine will likely misfire. A misfiring engine results in a jerking or sputtering feel when you are moving at normal speeds. When you stop, a misfire from a bad ignition coil may cause your vehicle to run roughly, vibrate or shake.
Vibrations can damage ignition coil windings and insulation causing shorts or breaks in the secondary windings. The overheating of ignition coils can hinder their ability to conduct electricity. Wear and tear is a common reason for ignition coils failing.
How Long Do Ignition Coils Last? Ignition coils generally last 80,000 to 100,000 miles. However, as with most vehicle components, certain conditions like the ones below may cause them to fail sooner.
In addition to being more reliable, coil packs are generally credited with providing more horsepower and torque than a common distributor. Because a coil pack generally creates a much more efficient spark, it also known to provide a slight fuel efficiency improvement over vehicles that use standard distributor caps.
If you have a faulty coil, it`s going to cost you between $200 and $300 on average to replace it, not to mention the frustration and downtime you`ll experience. Learn more about what an ignition coil is, what it does, ignition coil replacement cost, and how you can tell when it`s bad.
For some V6 engines (6 cylinder), the intake manifold has to be taken out to access the bad spark plug, taking the labor costs as high as $260-$320 for the vehicle. In total, spark plugs replacement can cost you anywhere from $100-$250 on the low end and $250-$500 on the high end (usually for a V6 engine).
The ignition coil on car is supposed to last around 100,000 miles or more. You will have reduced gas mileage when coil begins to go bad and becomes less able to transfer power. Your car requires more fuel to run, this means you will spend more money on gas than normal.
In this type of system, a four-cylinder engine has two coils, a six cylinder has three coils, and a V-8 has four coils. The coils are often mounted together in a coil pack, Figure 10-10.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

I put the wrong key in my car and a few weeks later my car just shut down and it will not start I believe it’s the computer but…
ANSWER : Hi there. What had happened is the wrong key set the security to the vehicle. This is to prevent the vehicle from starting with the wrong keys. Try removing the battery cables (+) and (-) for 13 minutes. During that time, put the original key in the ignition and turn it on. Activate everything in the car even though there is no power. Then remove the key and hook up the battery cables. The computer should have reset and reset the security. If the security is still being tripped, then I recommend seeking out a professional, such as one from Your Mechanic, to help you

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Replaced alternator on car 2 times each time shows it’s charging 14v let car run for a little bit then test drive and car voltage
ANSWER : There are reports that the replacement alternators will not communicate with the engine computer and will not charge correctly. I recommend using only the manufacturer approved replacement part. It can be new or remanufactured but approved for use in the vehicle. Some lower cost alternators on the aftermarket will have charging problems since they will not communicate with the ECM on the vehicle and will stop charging.

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Oil leaking from under car and "remote control car" sound when car is first started for a few minutes until it warm up.
ANSWER : Hello,
There are a number of things that could make an engine noisy when starting up. Depending on the specific type of sound you are referring to, this will determine how to properly diagnose. If there is a bit of a hissing sound, this may be a sign of a vacuum leak. If this is more of a shrieking sound, this may be a sign of a worn out or out of adjustment serpentine belt. If there is a bit of a howling or growling sound, this may be a sign of a worn out or low on fluid power steering pump. A rattling or pinging sound may be caused by an ignition problem. An engine can ping (or knock) due to an improper combustion process. A "spark knock" is the result of combustion occurring too early. Early combustion can occur from carbon buildup inside the combustion chamber, a lean air/fuel mixture, and advanced ignition timing (spark plug firing too soon). A clattering type sound may be a result of improper lubrication in the valve train which could be a more serious problem and should be addressed as soon as possible. I would suggest having an expert from YourMechanic come to your location to diagnose and inspect your vehicle to ensure everything is in proper working order.

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Battery and oil light come on when trying to start car, take keys out try again car starts no problem and lights go away
ANSWER : Of course, don’t switch gears without being fully stopped, unless your Owner’s Manual or the manufacturer has alternative advice. However, the gear shift issue has no relation to the no-start problem you are describing. Inasmuch as you only have 6,000 miles on the car, the "constant on and off" that you believe has occurred is meaningless in comparison to the expected total vehicle service life. That is, assume what you perceive as "constant on and off", during merely 6,000 miles, might be equivalent to using the car "normally" for three years. A new car should be trouble free for at least 5 years, unless there is a defect, so your "constant on and off" is not a causal factor for any fault on the vehicle. What you might have is a defect in the ignition switch, or perhaps the immobilizer system, but if the problem is not in the switch itself, clearly there is an electrical problem.

If your vehicle is under warranty, by law the dealer MUST repair the issue you are describing within a prescribed time frame and number of "attempts", otherwise the dealer will run afoul of Federal and state Lemon Laws that give you very specific rights, and recourse (contact an Attorney; we are Mechanics, NOT attorneys). Consequently, if the vehicle is still under warranty, to save yourself money do be sure to seek a resolution from the dealer. If the vehicle is not under warranty, obviously a certified Mechanic from YourMechanic could identify the electrical fault and resolve this for you. If you want to go that route, please simply request a no start diagnostic -electrical system and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Power steering loss, no belts are turning but the car is running fine. I also have a soft pedal. Whats wrong with my car?
ANSWER : I have only seen this situation once in my 30+ years and it turned out to be a broken crankshaft pulley. Belts are driven by the engine. The crankshaft pulley spins the belts, which in turn spin the air conditioner compressor, power steering and water pumps, and the alternator. The vehicle should be towed to your local repair shop and not driven. Without the water pump spinning to circulate the coolant, the engine will quickly overheat and result in more extensive damage.

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Should I buy this car for $1700
ANSWER : Prior to buying any car, drive the car around and listen for any noises. Then do an inspection on the vehicle to make sure that it is safe to drive. All cars will need maintenance, but if the car was kept up, then the maintenance should be to a minimum.

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My car will not start Intermittently. I purchased a new battery 2 weeks ago and yesterday the car wouldn’t start. Got a jump and
ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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Car crash and SRS light
ANSWER : Hey there. It is likely that your front impact sensor was damaged during the frontal collision but not with enough force to deploy the air bags. There is a threshold for how hard a vehicle must be hit in order to deploy the airbags that is set by the manufacturer that may not have been met. When the SRS light is illuminated, this means that the air bags will not deploy in the event of an accident, even if it is hit hard enough. I would recommend having the frontal collision sensor inspected and replaced if necessary by the dealer or a professional who is proficient in air bag repair.

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