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How do I correct misfiring on #4 cylinder,already change coil pack & plug have voltage across the plug of injector getting the same code P0304 ,the problem use to be intermittent,now permanent
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P0304 is engine misfire #4 cylinder Several things can cause a misfire #1 electrical which you have covered #2 Mechanical Test engine compression is should be around 150 cranking and 120 running . internal valve train components can cause bad compression and the valves then self. #3 fuel injector can be the cause suggest swapping with a know good cylinder and see if misfire follows injector.
The P0304 code means that the cylinder 4 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 4. If the problem persist more tests needs to be done to diagnose problem, see "Possible Causes"
- Faulty spark plug 4
- Clogged or faulty fuel injector 4
- Faulty ignition coil 4
- Fuel injector 4 harness is open or shorted
- Fuel injector 4 circuit poor electrical connection
- Ignition coil 4 harness is open or shorted
- Ignition coil 4 circuit poor electrical connection
- Insufficient cylinder 4 compression
- Incorrect fuel pressure
- Intake air leak
most likely change your spark plugs these should be done every 60,000 km
First thing I would like you to check is your firing order. While one misfire can make the engine hesitate and run awful it is not likely to preven all together starting.
Here is your firing order, double check
You said you changed the coil pace, wires and plugs not long ago and still get the code correct? Assuming the firing order is correct we will move on.
Swap fuel injectors from and cylinder with #4. Now reset the codes and see if the code remains a P0304 or weather it moves. If it moves to the cylinder you swapped the injector with the the injector is at fault. If not the the injector itself is not the problem.
A smell of rotten eggs out of the tail pipe can be the sign of a bad catalytic converter. a P0304 alone rarely means the converter could be at fault it could be as well as a faulty computer.
I might suggest to switch the wire from #4 with another cylinder just to make sure you did not get a faulty wire and I would pull the plug from #4 and make sure it is not fouled again.
After all of the things you tried and the injector sway I would suggest that you put a pressure gauge on that cylinder and see if you have decent pressure. You could have an undetected head gasket failure, worn valve. A leak down test may have to be performed if the pressure is low to find out where the leak is.
Possible causes:
Faulty spark plug
Clogged or faulty fuel injector
Faulty ignition coil
Fuel injector
Harness is open or shorted
Fuel injector circuit has poor electrical connection
Ignition coil harness is open or shorted
Ignition coil circuit poor electrical connection
Insufficient cylinder compression
Incorrect fuel pressure
Intake air leak
The P0304 code means that the cylinder 4 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 4.
P0304 Code - Cylinder #4 Misfire Detected A P0304 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #4.
Symptoms may include: * the engine may be harder to start * the engine may stumble / stumble, and/or hesitate * other symptoms may also be present
Causes: A code P0304 may mean that one or more of the following has happened: * Faulty spark plug or wire * Faulty coil (pack) * Faulty oxygen sensor(s) * Faulty fuel injector * Burned exhaust valve * Faulty catalytic converter(s) * Running out of fuel * Poor compression * Defective computer
Possible Solutions: If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.
If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.
The MAF sensor is not the problem, these are cylinder misfires on #1,3 and 4. replace the #4 coil pack, #1 AND 4 use the same coil, replace the spark plugs and the wires.
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