Engine misfire

Engine misfire and temp loss of power. Just started tonight. Spark plugs have over 100 thousand miles on them. It was also about a quart low of oil (no leaks that I can tell) and is overdue for an oil change. Could this be the plugs?
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
Hi Dave,
Engine misfires can be caused by many different problems and are generally caused by either a spark or fuel issue or in some cases, a combination of both. Spark related problems generally will result from things like ignition coils, crankshaft position sensor, spark plugs, spark plug wires or ignition modules not working properly. When the misfire results from a fuel related issue, this is commonly related to a lean fuel condition (lack of sufficient fuel supply to the motor). Fuel related misfires can be caused by many different things such as low fuel pressure, faulty or dirty fuel injectors, a faulty O2 sensor, a dirty or failing mass air-flow sensor, a faulty or dirty idle air control valve or a vacuum or intake leak. When the fuel supplied to the combustion chamber is insufficient, this results in an ignition (spark) that is igniting a less than balanced load of fuel and air. This results in a misfire or an explosion in the cylinder that is much less powerful than the other cylinders. This creates a loss of power that resonates throughout the motor additionally causing other problems with ignition and fuel timing. Due to the number of different things that may cause an engine misfire, the quickest and easiest way to diagnose this type of problem is to hook the vehicle up to a scanning tool which will download any potential fault codes that may have registered in the vehicle’s computer as a result of the poor running condition. I would recommend having an expert from YourMechanic come to your location to diagnose your misfiring problem.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Ford Taurus P0300 Causes

Multiple misfires can be caused by many reasons from a faulty ignition system, fuel system, or internal engine failure. The most common reason for this to happen is faulty or worn-out spark plug coil packs, especially if it`s been a while since you had a tune-up.

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.
Ford Taurus P0303 definition: Cylinder 3 misfire detected. Issue Severity: SEVERE – Stop driving immediately. Repair Urgency: Fix this code immediately (same-day if possible) to avoid ignition failure, catalytic converter damage, and dangerous conditions.
What Does Ford Taurus Code P0301 Mean? Ford Taurus P0301 definition: Cylinder 1 misfire detected. Issue Severity: SEVERE – Stop driving immediately. Repair Urgency: Fix this code immediately (same-day if possible) to avoid ignition failure, catalytic converter damage, and dangerous conditions.
A clogged or failed exhaust gas recirculation or crankcase ventilation valve or faulty oxygen sensor can send the wrong signals to the computer and cause misfires.
Misfires don`t simply go away – they need to be addressed immediately. Even if they don`t get worse, they certainly won`t get any better unless you take the car to a mechanic.
Several reasons could trigger a cylinder 3 misfire. Common causes include ignition system troubles, fuel delivery issues, or leaking valves. However, a faulty or worn-out spark plug or ignition plug coil pack is the most common cause of the misfire.
Dirty fuel injectors may cause your vehicle`s engine to misfire. This problem makes the motor feel as though it is sputtering — sending vibrations through the car. Such misfires can happen when a fuel injector problem mixes up the delicate balance between fuel and air entering the engine.
A weak pump that isn`t delivering adequate pressure can cause an engine to run lean, misfire and hesitate when accelerating. The volume of fuel is just as important as pressure. A good fuel pump is usually capable of pumping at least 750 ml (3/4 quart) of fuel in 30 seconds.
The P0301 code means that cylinder 1 has a misfire and isn`t burning fuel properly. Bearing in mind that you need air, fuel and spark for combustion, the cause of a P0301 code could come from a few different sources. In any event, a P0301 code is serious and shouldn`t be put off.
Dirty or Old Spark Plugs

If your engine is misfiring, you may be able to fix the problem easily by replacing your spark plugs. Spark plugs are relatively easy to remove from engines and inspect for damage, and at less than $25 a piece, they are relatively cheap to replace, too.

A misfire will cause the engine to momentarily stumble, or lose rpms, and then regain its normal engine speed. The misfire will usually reappear, either under specific operating conditions or randomly. A misfire may occur when your engine is idling, causing a rough or uneven idle.
The OBD II system detects misfires on most vehicles by monitoring variations in the speed of the crankshaft through the crankshaft position sensor. A single misfire will cause a subtle change in the speed of the crank.
If you start to experience engine misfires, stalling, or rough idling when the car is stopped, it can also be a warning sign of a failing TPS. You don`t want to wait to get this checked out! If the idling appears off, it means the computer is unable to identify the fully shut throttle.
Engine Misfires: A failing camshaft position sensor can cause your engine to misfire. Transmission Shifting Problems: The data sent to the engine control module can stop the transmission from shifting properly.
An engine misfire can be caused by bad spark plugs or imbalanced air/fuel mixture. Driving with a misfire isn`t safe and can damage your engine.
An engine misfire can be temporary or continuous and will sometimes generate a check-engine code.
Good quality fuel injectors rarely cause misfires whereas, poor quality or faulty injectors cause destructive misfires. The vehicle can experience various misfires when a faulty injector is a reason; it can lead to a loss in acceleration, power, and reduction in fuel efficiency.
The misfire can be caused by a worn spark plug, defective coil, faulty spark plug wire, faulty injector, plugged injector (each injector has its own miniature internal filter), mechanical valve fault and so forth. The most common issue is the spark plug is simply worn out or defective.
In most 3-cylinder engines the occurrence of vibration is higher at slower speeds due largely to the fewer number of power strokes (number of times the cylinders are fired). This tends to even out at higher speeds and at higher engine rpm levels.
While you can still drive a car with a misfire, it`s not a good idea. A misfire could be a sign of several different engine issues. If you continue to drive without resolving the issue that caused the misfire in the first place, it could potentially cause more extensive damage to your engine over time.
For example, the problem could be caused by a defective spark plug or wire, which is quite simple to fix in the great scheme of things. However, the error code could be caused by a damaged catalytic converter or computer system, which can be costly.
You might get a misfire code after spark plug replacement for an individual cylinder like a P0303. The code indicates a misfire in cylinder three. Sometimes the spark plug is dropped, and the ground electrode and the center electrode can make contact. Or the problem could be with the connection to the coil.
If your vehicle is revving inconsistently or your RPM gauge is up and down, this may be a sign your fuel injector needs a clean. A contaminated fuel injection system or worn fuel injector can often supply inconsistent amounts of fuel to the engine, resulting in poor performance. Misfiring.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Engine misfires and check engine light is always on
ANSWER : It’s always a good idea to pull over and turn off your vehicle when the check engine light is blinking. A blinking check engine light usually means there is a severe misfire in one or more of the cylinders. Most of the time, a misfire symptom is the result of a fouled spark plug. Honda now recommends changing spark plugs at 110,000 miles, however it is a known fact that spark plugs are considered a wear item and they do indeed wear out. There are a lot of factors that go into a spark plug wearing out or prematurely wearing out. One thing to consider is the type of gasoline being used in the vehicle. A top tier gas is recommended in most newer vehicles. This is because top tier gas contains additives which keep the engine free of deposits that may cause spark plugs to foul prematurely.

Honda is aware of this concern and has issued a technical service bulletin to help reduce and, in some cases, eliminate this concern. This technical service bulletin advises the technician to update the vehicle’s engine computer. This update improves fuel injector and variable camshaft timing during cold starts and eliminates excessive fuel from fouling out the spark plugs. I recommend you have a certified mechanic inspect your ignition system to determine the exact cause of this misfire so the proper repairs and preventative maintenance can be performed and get you back on the road again.

Read Full Q/A … : Engine misfire

Honda Pilot engine misfire when cold out and engine running warmer than usual?
ANSWER : Hi There,
It sounds like you may have a faulty coolant temperature sensor. This sensor relays the temperature of the coolant back to the ECM which uses this information to control many things such as when to turn the coolant fans on and off as well as how much to adjust the air to fuel ratio in the motor. Both of these functions are affected when this sensor is not working properly. If the senor is reading incorrectly, this may cause inaccurate temperatures to be read, thus causing inaccurate adjustments to be made to fuel and to the operation of the cooling fans (i.e. staying on too long or not coming on soon enough to help keep the motor cool). I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.

Read Full Q/A … : Engine misfire

Can front wheel drive car engine power rear wheel drive
ANSWER : Anything is possible with enough engineering. The changes you are looking at would take major structural changes and would definitely not be an easy job. You could possibly consult a manufacturing engineer to get more details on how this could actually be carried out and whether it would be feasible.

Read Full Q/A … : Engine misfire

Check engine light refuses to go off after engine replaced
ANSWER : Hello there, you have a long series of issues going on with your 2013 Hyundai Sonata. If you keep getting a repeating oil light on than there is likely a fault in that system.

Since this fault has lasted after the engine was replaced it could be a oil pressure sensor, wiring harness fault, ECU fault, oil pump, oil strainer clogged, or low oil pressure.

To diagnose this issue properly you need a complete vehicle inspection to start from square one and identify the root cause of all this.

Read Full Q/A … : Engine misfire

Engine malfunction light, reduced engine power, engine powered down
ANSWER : Hi there. There are a lot of things that can cause this on your 2012 BMW M5. I usually start by scanning the computer for codes to see what comes up. If there are not codes then I load test the alternator and the battery to see if they are failing. Low voltage in the electrical system will cause this. If that is fine, then it is usually caused by a failing throttle body. I have seen a lot of these fail due to the motors in them hanging up. If the problem is only happening intermittently, this can make the issue hard to duplicate, but you can still have tests done on the car. If you are going to have this fixed, consider YourMechanic, as a certified mechanic can come to your home or office to test the vehicle and diagnose the Engine Malfunction Light.

Read Full Q/A … : Engine misfire

I have a 2010 camry. I just recently replaced the engine with a 2014 camry engine. Now I have Four engine lights on. I replaced on
ANSWER : If you swapped the engine from a vehicle that is 4 years newer than the car is then you are going to have electrical and sensor incompatibilities that may not be able to be fixed by just a few sensor replacements. There were many changes in computer and emission related items between 2010 and 2014 engines. I would recommend having a mechanic like one from YourMechanic come to you and compare the two engines to isolate the possible differences and see if the problem can be fixed.

Read Full Q/A … : Engine misfire

How do you replace the rear & side engine mounts without lifting out the engine? & how do you lift the engine out?
ANSWER : Hi…thank you for your questions. If required in the application, a portable engine support bar is used to support an engine during mount replacement. The support bar has lifting capability as well so that the mount can be unloaded and removed. If a particular repair application requires a "crane" (complete engine removal for instance), such are portable these days in any event. With regard to the exhaust system repair, mechanics use ramps to gain access. Six ton portable jack stands will safely support a car two feet into the air which provides more than enough access to repair or replace any exhaust system component. If you desire replacement of the mounts, please refer to YourMechanic’s motor mount replacement service page. For exhaust leaks, please use the exhaust system inspection/repair page page. Once on each of those service pages, if you click on "Get a Quote" and enter your vehicle information (year, make, model) you can obtain cost info and schedule the service. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

Read Full Q/A … : Engine misfire

Code said cylinder 1 misfire, cylinder 2 misfire, o2 sensor misfire?
ANSWER : Without checking the ignition coils and spark plugs myself for proper spark output I would say the engine is misfiring and may be the coils and plugs. It is also common for the valve cover gasket to leak oil into the spark plug tubes shorting the coil and spark plug out so it cannot fire. The check engine light is flashing due to the misfire is active and additional catalyst damage can happen if you keep driving with the misfire and raw fuel dumping into the catalyst. I would recommend having a mobile mechanic like one from YourMechanic come and do a through diagnosis to see if the valve gasket is leaking into the spark plugs and caused damage to the coils and spark plugs. If it is leaking then the valve cover gasket should be replaced with the spark plugs and contaminated ignition coils replaced then computer codes an be cleared and the vehicle road tested for any other problems from driving the vehicle with the engine misfiring.

Read Full Q/A … : Engine misfire