What causes a cylinder to have a misfire code?

When you have a misfire code for a particular cylinder, you can focus on one of three things: an ignition problem, a fuel injector problem or a compression problem. Every time a spark plug fires, the spark burns a few molecules of metal off the plug’s electrodes.

What is the code for a failed coil?

Neither code is a slam dunk diagnosis for a failed coil. Instead of throwing a set of anything, let’s concentrate on cylinder #5. SWAP positions of 2 coils.

What does the misfire code p0305 mean?

P0305 is a cylinder specific misfire code, which means that Cylinder 5 is misfiring and causing it. An important thing to understand when finding the location of Cylinder 5 is that it’s going to be the fifth cylinder in the firing order. It won’t be the fifth cylinder that you might see when looking at the engine.

How can I tell if my engine is misfired?

Misfires that turn on the check engine light and log a cylinder-specific fault code are the easiest to diagnose. A flashing check engine light and a P0301 to P0312 diagnostic trouble code (DTC) is a surefire indication that one or more cylinders are misfiring.

What happens when a cylinder 5 misfire is detected?

The engine will have a misfire causing a buck or jerk and a rough idle. The engine may lack some power during acceleration while the misfire is active. How does a mechanic diagnose the P0305 code? Removes cylinder 5 ignition coil or plug wire and checks for evidence of spark tracking on outside of coil or plug boot.

What is the trouble code for cylinder 5?

P0305 is a diagnostic trouble code (DTC) for “Cylinder 5 Misfire Detected”. This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic.

When do I get a misfire code on my engine?

Misfire codes do not always indicate there is an issue with the ignition system. A misfire code is set when the computer detects a situation where there is an unexpected change in crankshaft speed. With most engines, the crank sensor is the key component in determining a misfire.

Neither code is a slam dunk diagnosis for a failed coil. Instead of throwing a set of anything, let’s concentrate on cylinder #5. SWAP positions of 2 coils.

How to fix a misfiring cylinder in a car?

Step 6 – Once the misfiring cylinder has been located, remove the spark plug for inspection, before removing the spark plugs, mark the plug wires (if equipped) to identify their positions in the firing order, this will help for proper reassembly. Step 7 – When a cylinder (s) runs rich it will carbon foul the spark plug causing it to short circuit.

Why do I keep getting misfire codes on my cop?

Insufficient valve lash, a broken piston ring or a leaking cylinder head gasket can cause a partial loss of compression. Depending on where the vacuum leak is on the manifold, it can generate random or specific cylinder misfire codes. The most common failure in COP ignitions is carbon tracking or “flash over” on the spark plug insulator.

What should I do if my civic engine is misfiring?

Swapping plugs on a ’90s Civic’s inline four cylinder is easier than in a 1970 Corvette’s narrow engine bay stuffed with an LS5 454. You’ll just need a couple of basic tools to get started and our how-to guide. Even if the code reader shows only cylinder No. 1 is misfiring, replace all the spark plugs at the same time.

When does a broken valve spring cause a misfire?

If a camshaft lobe is halfway worn down, it will show up only when the engine is running and under load. Step 19 – In some conditions a broken valve spring can effect different aspects of engine performance for example: If just a small part of a coil breaks off, the spring can still close the valve but only at low RPM’s, causing a high RPM misfire.

What’s the correct firing sequence for multiple cylinders?

Repeat steps 7-14 on the remaining five cylinders using the firing sequence 1-2-3-4-5-6. Make sure the piston is at TDC in each cylinder of the exhaust valve spring retainer lock that is being removed. When all the exhaust valves have been rotated 90° and all the exhaust valve spring retainer locks have been replaced, proceed to the next step.

Can a single cylinder misfire cause Mil illumination?

In addition, MIL illumination may also have occurred due to DTC P0300 – Multiple Cylinder Misfire. Various single cylinder misfire DTCs may also be present. If the frequency of misfire is high, the powertrain control module (PCM) may place the engine in “limp-in” mode.

What kind of compression tester do I need for cylinder 1?

Install the compression tester spark plug adapter in cylinder #1 spark plug hole. With the air hose attached to the spark plug adapter, apply 620.5 to 689 kPa (90 to 100 psi) air pressure. This is to hold the valves into place while servicing the components.

What to do if your car engine has rough idle?

If you own an old car and are experiencing rough idling, it is a good idea to clean the carburetor and check the hoses for damage or dirt buildup. Rough idling is a serious issue and should not be ignored for a long time. If the problem persists and is not fixed, it can lead to engine failure as well.

Can a misfire be a missing spark from an ignition coil?

The reality is that a misfire can be more than a missing spark from an ignition coil. Misfires that are below the vehicles threshold often pass unnoticed, but a constant misfire is hard to be overlooked by you or the engine management system.

Can a failed ignition coil cause engine damage?

When carbon tracking is found, the coil and corresponding plug should be replaced. It is also possible that a failed ignition coil can cause damage to the engine computer, or ignition control module. Commonly an engine computer detects a misfire by measuring the changes in crankshaft speed.

Why are all cylinders misfiring after coil and plug replacement?

Compression test is needed. Also, you stated plugs were replaced — were the old plugs oil fouled at all? These engines could have piston and ring issues due to lack of maintenance (enough frequent maintenance, that is…), and the spark plugs can get fouled quickly.

What does a p0303 fire code tell you?

A P0303 code, for example, would tell you that the No. 3 cylinder is misfiring. To figure out which cylinder is No. 3, refer to a diagram of the engine’s firing order or look for markings on the intake manifold, spark plug wires or ignition coils (if the engine has a coil-on-plug ignition system).

What causes a spark plug to misfire on a car?

Eventually the ignition system reaches a point where it fails to produce enough voltage and the plug misfires. Bad spark plug wires are another common cause of misfires. After 50,000 miles or so, OEM carbon-core ignition wires develop too much internal resistance, which weakens the spark and increases the risk of misfire.

Are there any misfires on CYL 2, 4, 6?

Misfires on cyl 2,4,6 wth am i missing!?!? 2011 nitro heat with 4.0L had code P0300 in system. This is what i have done so far and still getting misfire counts on cyl 2,4,6 only. Performed compression test 225psi all cylinders but number 2 which was 220psi. Smoke test for intake leaks, small leak at the egr tube. replaced gasket and retested ok.

How to find out if you have a misfire code?

Misfires are one of the hardest things to track down and they’re almost impossible to diagnose over the internet. This gives people a great place to start. Yesterday I’ve replaced 4 plugs and 1 coil pack.

Where are the misfire codes on my pick up?

The check engine light (CEL) will be on. One or more misfire codes (P0300-P0304) will be stored in your pick up’s PCM memory (PCM = Powertrain Control Module = fuel injection computer). P0300 Random Cylinder Misfire. P0301 Cylinder #1 Misfire. P0302 Cylinder #2 Misfire. P0303 Cylinder #3 Misfire. P0304 Cylinder #4 Misfire.

How to diagnose misfire codes for Ford 4.6L?

P0308 Cylinder #8 Misfire. 1 1 Misfire. 2 P0302 Cylinder #2 Misfire. 3 P0303 Cylinder #3 Misfire. 4 P0304 Cylinder #4 Misfire. 5 P0305 Cylinder #5 Misfire. 6 P0306 Cylinder #6 Misfire. 7 P0307 Cylinder #7 Misfire. 8 P0308 Cylinder #8 Misfire.

What happens if you have two misfiring cylinders?

It’ll be missing fuel (gasoline), or spark, or air (compression). So, if just one of the four cylinders is ‘dead’, the engine’s idle and performance will be affected for the worse. If your Toyota has two misfiring cylinders, it’s not gonna’ start and run and if it does… it’s not gonna’ go anywhere. The check engine light (CEL) will be on.

What does it mean when cylinder 1 misfire?

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.

What does it mean when cylinder 1 has a trouble code?

Some systems may take several failure cycles before registering a trouble code again. 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.

What are the symptoms of a BMW cylinder 4 misfire?

The symptoms of cylinder 4 misfires include misfires, engine running poorly, lack of engine power, and decreased fuel mileage. What causes the P0304 code? · Hook up a scan tool to the DLC port to determine which codes are present.

How can you tell if a cylinder is misfiring?

The engine computer or PCM can detect a misfiring cylinder by monitoring the engine speed. Once misfire is detected, the PCM sets the trouble code and turns on the Check Engine light to alert the driver.

What can cause an OBD-2 engine to misfire?

On OBD-II cars, the OBD-II system will not only identify misfires, but also coil and injector problems. Consequently, if the (MIL) lamp is on and you find a code for a misfiring cylinder; and a second code indicating an injector fault for the same cylinder; bingo, the engine probably has a bad fuel injector.

Can a bad spark plug cause an engine to misfire?

If you have separated spark plugs, unplug each coil to see if you can find out if any cylinders are not responding. Replace if you find one faulty or have a trouble code stored for one ignition coil. 2. Bad Spark Plug The second most common cause of a misfire is bad spark plugs.

What could be causing a cylinder to misfire?

Another reason a cylinder may misfire is due to a loss of spark . This can be something that stops coil voltage from hopping the gap at the end of the spark plug, such as worn out or corroding parts. Damaged, worn, or bad spark plugs, or a weak ignition coil can cause a loss of spark, and therefore, a misfiring cylinder.

How to tell if my cylinders are misfiring?

Is it Safe to Drive With a Misfiring Cylinder? Loss of Power Accompanied by Abnormal Vibrations. One of the biggest signs your cylinder is misfiring is the loss of power along with odd vibrations. Loss of Engine Spark. Another reason a cylinder may misfire is due to a loss of spark. Imbalanced Air/Fuel Mixture. Intermittent Misfires.

How serious is a cylinder misfire?

Misfires reduce gas mileage and increase emissions, which can cause you to fail an emissions test. More seriously, cylinder misfires can cause damage to other engine parts, like the oxygen sensors or catalytic converter.

Is it safe when driving with a misfiring cylinder?

Driving with a misfiring cylinder is not safe under any condition. It can cause severe damage to your car’s engine and thus most of the people advise not to drive with this problem.

What causes a car to misfire after 50, 000 miles?

After 50,000 miles or so, OEM carbon-core ignition wires develop too much internal resistance, which weakens the spark and increases the risk of misfire. High-mileage plug wires also can develop cracks that leak current to ground or to other wires, shorting the spark before it can reach the plug.

What causes a fuel injector to misfire?

These ignition and fuel delivery systems include a damaged fuel injector solenoid, a broken ignition coil, or a dirty fuel injector. These cylinder misfire causes may not set off a diagnostic code but will need to be fixed to prevent the cylinder misfiring from getting any worse. Another common cylinder misfire cause is bad spark plug wires.

What causes a cylinder to catch on fire?

Another common cylinder misfire cause is bad spark plug wires. Just like any other part, the spark plug wires can break down over time and after consistent use. After nearly 50,000 miles, the spark plug wires might leak current, causing a short circuit before the spark can set off the ignition at the right time.

What would cause misfire on every cylinder?

Low fuel pressure will cause a lean mixture in your engine, which will result in misfires on all cylinders. If you have trouble codes for misfires on all cylinders, you will want to check your fuel pressure.

Would bad spark plugs cause misfire in cylinder?

This can be something that stops coil voltage from hopping the gap at the end of the spark plug. Damaged, worn, or bad spark plugs, or a weak ignition coil can cause a loss of spark, and therefore, a misfiring cylinder. If there is not enough gasoline in the air/fuel mixture , this can cause a misfire as well.

What is causing cylinder 3 to misfire?

P0303 indicates that cylinder number 3 is experiencing misfires. A misfire occurs when an insufficient amount of fuel is burning in a cylinder.

Is it possible to find a misfire in a Ford?

It’s possible to find a misfire in your Ford, even if there is no check engine light. All you need is an OBDII scanner with Mode 6 function. It is a common situation. You’re driving your F150, F250, E150 van, or Expedition, etc and you can feel the engine skipping here and there.

Is there a way to find a phantom misfire?

YES there is a way to find these misfires! Often called “phantom” misfires. It’s possible to find a misfire in your Ford, even if there is no check engine light. All you need is an OBDII scanner with Mode 6 function. It is a common situation.

Is it OK to drive an engine that is misfiring?

Instead from that, misfires can damage other sensors in the engine like the O2 sensors. So, I would never recommend driving an engine that is misfiring for any long distances. Short distances to your mechanic workshop without putting a load on the engine is fine, but do not ignore the misfires and keep driving.

What are the misfire codes on a Buick Enclave?

Did nothing. These were the codes it was throwing: 300 (random misfire), 102 Mass or Volume Air flow Circuit Low Input), 113 (Intake Air Temp Sensor 1 Circuit High Input), 202, 204, 206 (Injector Circuit/Open- cylinders 2, 4 ,6) and 449 (Evaporative Emission System Vent Control Circuit Intermittent).

What are the most common signs of engine misfires?

The most common situation to notice misfires is on high gears, low RPM, and the accelerator to the floor. Rough acceleration is a typical sign that your engine is misfiring.

What does p0301 Mazda cylinder 1 misfire condition mean?

P0301 MAZDA Tech Notes The P0301 code means that the cylinder 1 is misfiring or is randomly misfiring. Start by checking for intake leaks and if no leaks are found the next step is to replace the spark plugs on cylinder 1. If the problem persists more tests needs to be done to diagnose problem, see “Possible Causes” What does this mean?

What happens when a misfire occurs in a Mazda?

When a misfire occurs, engine speed will fluctuate. If the engine speed fluctuates enough to cause the Crankshaft Position ( CKP) sensor signal to vary, the Engine Control Module ( ECM) can determine that a misfire is occurring. Need more information on how to fix the P0301 MAZDA code?

What causes a Mazda cylinder to malfunction?

P0301 MAZDA Possible Causes Faulty spark plug 1 Clogged or faulty fuel injector 1 Faulty ignition coil 1 Fuel injector 1 harness is open or shorted Fuel injector 1 circuit poor electrical connection Ignition coil 1 harness is open or shorted Ignition coil 1 circuit poor electrical connection Insufficient cylinder 1 compression

Why does my spark plug keep misfireing?

The erosion gradually increases the gap between the electrodes, which, in turn, increases the firing voltage required to generate a spark. Eventually the ignition system reaches a point where it fails to produce enough voltage and the plug misfires. Bad spark plug wires are another common cause of misfires.

What causes a P0300 to misfire at idle?

Looks like the 2nd drive cycle is when it throws it’s codes. Let it idle for a minute, and it kicked back a P0300, random misfire. After saying a few choice words, I took a walk and picked up 6 new plugs and the socket, best case scenario, I’ll have some spare plugs and a coil pack for down the road.

How does the OBDII system work for a misfire?

The OBDII system can identify the cylinder (s) that are not contributing their normal dose of power and set a corresponding DTC. A P0303 DTC, for example, would indicate a misfire on cylinder number 3. If the ODBII system is unable to identify a specific cylinder a P0300 random cylinder misfire DTC will set.

Where are misfire codes stored in a Mercedes?

Luckily for you, the misfire codes are stored in the ECU and are very easy (and inexpensive) to retrieve. To diagnose an engine misfire on a Mercedes all you need is a generic OBD II code reader that can be bought in some cases for under 20 at your local auto parts store or on Amazon’s Best Selling OBD II scanners list.

How much does it cost to replace ignition coil on Mercedes E320?

Failed spark plug wires and/or ignition coils can cause intermittent misfires (rough running); the Check Engine Light may also illuminate. Diagnoses of the ignition system will be necessary to determine which components are at fault. The average cost for a Mercedes-Benz E320 Ignition Coil Replacement is between $152 -$167.

What causes a cylinder to misfire in a Mercedes?

In most cases, a cylinder misfire is caused either due to old spark plugs that need to be replaced. A failed ignition coil or a bad spark plug wires. If none of the above fixes your misfire problem carefully analyze the fault codes, it is possible that misfire may be indirectly caused by another problem in the engine.

Can a clogged catalytic converter cause a misfire?

A catalytic converter that is clogged and is restricting the exhaust gasses from leaving the engine can also trigger multiple cylinder misfire. If your catalytic converter is clogged you will notice a drastic drop in fuel efficiency and real struggle getting your Mercedes to accelerate. If the cat is completely clogged your car won’t even start.

What does a P0300 cylinder misfire code mean?

The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persists more tests needs to be done to diagnose problem, see “Possible Causes”

How much does it cost to diagnose a Mercedes-Benz misfire?

The cost of diagnosing the P0300 MERCEDES-BENZ code is 1.0 hour of labor. The auto repair’s diagnosis time and labor rates vary by location, vehicle’s make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour. When is the code detected? When a misfire occurs, engine speed will fluctuate.

Lean misfire causes that only affect one cylinder include a dirty fuel injector, an open or shorted fuel injector, or a problem in the fuel injector driver circuit (wiring or PCM). Compression problems that may cause a misfire include a burned exhaust valve, bent intake or exhaust valve, or leaky head gasket.

What to do if you have a misfiring cylinder in your car?

If you are still having trouble finding the misfiring cylinder, you can disconnect the power to the fuel injectors one at a time to see what effect it has on the engine. Locate the connector where it attaches to the back of the fuel injector.

How to fix a misfire index 12 injector?

Finally I installed all brand new Index 12 injectors, and when I got to 6 I noticed that it simply fell all the way into the channel without any pressure needed to seat it down. I could then wriggle it slightly as it was totally loose in there. Drove the car and it immediately shut off 6 on first hard pull!

What to do if your fuel injector misfire?

A cylinder misfire will trigger an error code for each cylinder that’s misfiring. If you know it’s an injector, try running a can of seafoam through the car to clean it out. You should only need to add it to the gas tank and through the intake via a vacuum line.

What is the diagnostic code for a misfire?

How to troubleshoot a GM Truck misfire?

This isn’t the only symptom that your GM van, pickup or SUV might experience… here are some more that you might see: P0300: Random Cylinder Misfire. P0301: Cylinder #1 Misfire. P0302: Cylinder #2 Misfire. P0303: Cylinder #3 Misfire. P0304: Cylinder #4 Misfire. P0305: Cylinder #5 Misfire. P0306: Cylinder #6 Misfire. P0307: Cylinder #7 Misfire.

What should I do if my check engine light says misfire?

If your “Check Engine” light diagnosis shows a generic cylinder misfire code, you should start with the most likely culprits first. Fortunately, these are also the cheapest and easiest. Spark plugs are as low as $2 each, and can be swapped in about an hour with varying difficulty.

What does the misfire code P0300 mean?

P0300 is a general and random misfire code, which means that the code is not going to tell you which cylinder is causing the misfire. Something is causing cylinders to misfire at random, which is a lot less cut and dry than a cylinder specific misfire code.

What is the fault code for torque pro?

We recommend Torque Pro. OBD II fault code P0300 is a generic code that is defined as “Random/Multiple Cylinder Misfire Detected”, and is set when the PCM (Powertrain Control Module) detects either randomly misfiring cylinders, or misfires on multiple cylinders.

What causes a P0300 to misfire on multiple cylinders?

Infrequent misfires are recorded but not tied to a particular cylinder, and on some platforms, this stores a P0300. Typically, any situation that isn’t tied to a particular cylinder but is causing misfires on several different cylinders is suspect. Fuel contamination would be one possibility.

What does it mean when a cylinder is misfired?

If your scan tool’s misfire history indicates multiple cylinder misfires, focus on the cylinder with the most misfire counts. The misfire counts on adjacent cylinders are often “sympathetic” misfires that will often disappear when the primary misfire is repaired.

What causes an intermittent compression misfire in a car?

Diagnosing an intermittent compression misfire can be tricky if the problem is caused by a marginal failure like a carboned-up intake valve seat or a broken valve spring. In either case, the misfire might occur only under specific operating conditions.

How often does a PCM detect a misfire?

The PCM measures how often a misfire happens within two different rpm windows to determine the frequency/severity of a misfire. It stores misfires within a 200 rpm window of time and also within a 1000 rpm window of time. Obviously, a misfire that happens multiple times with a 200 rpm window is the most serious.

What to do if you have a spark plug misfire?

I suggest first removing and checking the spark plug and swap in a new one or swap with cylinder next to it. This way the misfire moves to other cylinder then you know it was plug and replace it. If misfire still on number one then check for spark and injector pulse and replace injector or coil as needed.

What is the error code for cylinder 3 three misfire?

Error Code P0303: Cylinder 3 Three Misfire Detected. Error Code P0303 is described as Misfire Detected, Cylinder number 3. This means the vehicle’s computer has detected a misfire in the engine’s cylinder, specifically the cylinder #3.

What does a misfire code on a check engine light mean?

Misfires that turn on the check engine light and log a cylinder-specific fault code are the easiest to diagnose. The OBD II system will identify the cylinder (s) that are not contributing their normal dose of power and set a code that corresponds to the firing order. A P0303 code, for example, would tell you that the No. 3 cylinder is misfiring.

What does the error code mean on a spark plug?

The error code refers to a specific cylinder misfire, which means it needs a more thorough diagnosis. For a cylinder misfire, you have to change faulty components, such as coils and spark plugs. This is to isolate the exact cause of the misfire.

What causes an ignition coil to misfire in a car?

The most common problem when it comes to misfires is the ignition coil. Some vehicles have a separate ignition coil on each spark plug, while some cars have one coil with a sparking cable to each spark plug. Older cars have a distributor and, in some cases, also an ignition coil.

Where can I find the misfire code for spark plugs?

Diagnostics > By Trouble Code > P0300 P0301 P0302 P0303… People ask me about misfire codes after they’ve replaced all the spark plug wires, coil, and plugs and they still have the code.

What to do if your fuel injector is not delivering fuel?

Start the engine. It should sound the same. Remove the spark plug. If the spark plug is dry, then the injector does not deliver fuel to that cylinder. If the spark plug is wet and smells like gasoline, then the injector on that cylinder is not your problem. Moving the suspect injector to another cylinder is one way of diagnosing the problem.

What makes a GM 4.8L misfire engine stall?

P0306: Cylinder #6 Misfire. P0307: Cylinder #7 Misfire. P0308: Cylinder #8 Misfire. Really bad gas mileage. Lack of Power when you accelerate your van, pickup or SUV. Engine may start, run for a few minutes and stall.

What are the symptoms of a Random Misfire?

Typically, a random misfire shows up because of an issue with the ignition or fuel system, the ignition timing, or engine compression. Symptoms That May Show Up Along With P0300 Include:

Why does my Volvo have a Random Misfire code?

Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 Volvo code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.

What does the Volvo P0300 misfire code mean?

If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 Volvo code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 Volvo doesn’t tell you specifically which cylinder (s) is/are mis-firing, nor why.

What makes a GM 4.8l engine misfire?

Now that we’re aware of the core essentials that each engine cylinder needs to run at a 100% power output.. in the next sections I’ll explore some of the specific components that fail and cause a misfire and misfire codes.

Can a bad cop coil cause a misfire?

Because anything from a BAD COP Coil to low engine compression can cause a misfire. Well, troubleshooting and solving a misfire doesn’t have to be hard. Armed with the knowledge of what can cause a misfire, rough idle condition and a specific testing strategy, you can easily find out what component is the one that has failed.

What does misfire code p0303 mean on VW TSI?

What you want to do is take the ignition coil from any other cylinder, say cylinder 3, and swap it with the coil in cylinder 2. If the misfire code moves the new cylinder (P0303), that means it’s a bad ignition coil. If the misfire stays on cylinder 2 (P0302) that means it is not the ignition coil.

What causes a 2.0T TSI engine to misfire?

Any one of these three components can lead to a misfire. However, on the 2.0T TSI engine, misfires are most commonly caused by a lack of spark. Without spark, the cylinder will not create any combustion, resulting in the cylinder not functioning or creating any power.

Navigation