Make sure all new spark plug setting are set right. I bought a set and the car still would not run right so we found two plugs had been dropped and had to be reset. After resetting the car ran good.
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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
If this has the coil over the spark plug try replacing the coil. If it still has wires replace the cap, rotor and wires. Do a compression test and check for a mechanical problem like a burnt valve.
There are so many things that can cause a missfire. Just a thought. IF you switch both the plug and coil with a different cylinder it should show the missfire on that cylinder. You might want to check the compression on cylinder number 4.
You may also want to check the continuity of the conectin to the number 4 coil pack.
Check the plugs that were replaced. They may have been cheap plugs. If number four plug is fouled you may have ring problems.
The p0172 is due to an O2 sensor in the exhaust seeing too much oxygen, the po300 is a missfire present and p0304 is cylinder #4 missfire, check plug and wire to #4 and repair, this should also take care of the p0172, if a cylinder is missing it is just pump air into the exhaust thus causing the code p0172.
code P0304 cylinder #4 missfire the test is somewhat long, you did the right thing with the plugs and wires, that is were we would have started also but now that, that did not work it is time to go to work,,,here is the test for the code.....good luck
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.
-Last number corresponds to which cylinder is misfiring.
Could be a faulty spark plug or wire. Try changing the spark plug from the 4 Cylinder to another and see what happens; If the different cylinder misfires, then it is the spark plug. If not, it could be the wires on cylinder 4.
p0304 means the computer has detected that cylinder 4 is misfiring. the most common cause of a misfire is a faulty spark plug or plug wire. depending on how long its been since a tune-up, they could just be worn out. you can look at where the plug wire snaps onto ignition coil to see if the coil tower is corroded, also another cause. other causes of misfire in one cylinder could be a faulty fuel injector or low compression on that cylinder. but ignition is the most common
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