Q: P0304 Misfiring on Cylinder 4

asked by on

My truck has been misfiring on the number 4 cylinder. And I have changed the coil pack and plug which has voltage across the plug of the injector. I’m also getting this code P0304. It use to come on periodically, but now the code stays on permanently. Do you know how to fix this?

Hello. If the spark plug and the coil have been replaced, then a compression test needs to be done. It is common for the valve seat to fail and cause this. When it fails, it causes low compression which then causes the misfire. If the compression is fine, then it is possibly a fuel injector issue, but that is not common for this vehicle. If you want to have this fixed, consider YourMechanic, as a certified technician can come to your home or office to diagnose the misfiring problem and resolve the issue.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. P0304 Misfiring on Cylinder 4

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Engine revs without touching gas pedal.

Now the engine computer will raise the engine idle speed automatically to compensate for the additional load of the AC compressor and the electrical load of the blower motor when the AC/Heater controls are operated. This increase should not exceed...

Q: Vibration in car.

The most likely problem you are describing is the front brake rotors are warped. The rotors would need to be replaced with the brake pads at the same time. I would recommend the brakes and front end be checked first...

Q: P0300 and P0305. Pending: P0304, P0306, P0171, P0174, P2196, P2198

Hi there. The issue that maybe happening is the are fuel injectors that are not firing and there is a vacuum leak on the engine. Possible multiple sensors are not working causing the P2196 and P2198 codes to appear. For...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...