Q: p0305 Misfire in Cylinder 5

asked by on

I currently have an error code of P0305. I have already replaced the spark plugs and the one coil on cylinder 5, the misfire is still there. Many people have told that they can smell gas when the car is running. I replaced all in the intake gaskets in hope that there was some kind of leak. I have done a compression test and also have the freeze frame data and it will both be below.

Freeze Frame Fuel System 1 Status: Closed Loop Fuel System 2 Status: Closed Loop Calculated LOAD Value: 32.94% Engine Coolant Temp :174.20 F Short Term Fuel Trim - Bank 1: 14.84% Long Term Fuel Trim - Bank 1: 0.00% Short Term Fuel Trim - Bank 2: 3.13% Long Term Fuel Trim - Bank 2: 0.00% Engine RPM: 700.00 RPM Vehicle Speed Sensor: 0.00 MPH Absolute Throttle Position: 4.31%

Compression Test Piston 1: Dry 160 - Wet 170+ PSI Piston 2: Dry 153 - Wet 170+ PSI Piston 3: Dry 160 - Wet 170+ PSI Piston 4: Dry 155 - Wet 170+ PSI Piston 5: Dry 157 - Wet 170+ PSI Piston 6: Dry 155 - Wet 170+ PSI

My car has 100912 miles.
My car has an automatic transmission.

The fuel injector could be faulty and/or plugged and that would explain the high short term fuel trim on Bank 1 which contains cylinder No. 5. Another possibility is a vacuum leak around the intake to that one cylinder. If so, that can cause a random misfire. If the lobes on the camshaft are worn, that can cause a misfire and other inefficiencies as well. I would first check for a vacuum leak. If no leak, secondary firing patterns on the misfiring cylinder should be examined on an oscilloscope. The waveform will help narrow the potential causes to fuel versus ignition. Another possibility is the random misfire is due to intermittent faults in the injector and/or ignition components so although these components appear to be in spec during static testing, in fact they are not reliable and are later, in service, operating intermittently. Finally, the ignition and fuel driver circuits in the PCM for the misfiring cylinder could be faulty; that is the absolute last thing to test though unless you happen to have handy a known good PCM that you can substitute. If none of these possibilities pan out, you can request a misfiring diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

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. p0305 Misfire in Cylinder 5

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: I am missing parts of my car, it's the part between the front tire and the engine, it looked like a cover of some sort

This is called the inner fender plastic liner and protects from water and dirt from getting into the engine area. You may have to special order a new one from a dealer or if you contact our customer service they...

Q: Loud ticking/soft knocking in engine is worse after tune up

The inconsistent idle is probably due to an engine management/sensor issue which would include the IAC valve but quite a few other components are possible causes, too. Mechanical engine noises stem from wear and damage. You might get some insight...

Q: transmission wont push back on clutch slave cylinder

Hello, The slave cylinder is meant to be bench bled just as a master cylinder is. If this is not done it can cause air to remain in the slave cylinder. This will allow the slave cylinder to fully compress...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
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...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...