Engine misfire?

DTC P0300: Random Misfire and Any Combination of the Following:

DTC P0301: No. 1 Cylinder Misfire

DTC P0302: No. 2 Cylinder Misfire

DTC P0303: No. 3 Cylinder Misfire

DTC P0304: No. 4 Cylinder Misfire

DTC P0305: No. 5 Cylinder Misfire

DTC P0306: No. 6 Cylinder Misfire

Special Tools Required

Pressure gauge adapter 07NAJ-P07010A
A/T low pressure gauge w/panel 07406-0070300
A/T pressure hose 07406-0020201
A/T pressure hose, 2,210 mm 07MAJ-PY4011A
A/T pressure adapter 07MAJ-PY40120
Oil pressure hose 07ZAJ-S5A0200

NOTE:

If the misfire is frequent enough to trigger detection of increased emissions during two consecutive driving cycles, the MIL will come on, and DTC P0300 (and some combination of P0301 through P0306) will be stored.
If the misfire is frequent enough to damage the catalyst, the MIL will blink whenever the misfire occurs, and DTC P0300 (and some combination of P0301 through P0306) will be stored. When the misfire stops, the MIL will remain on.
Troubleshoot the following DTCs first, if any of them were stored along with the random misfire DTC(s):

P0107, P0108, P1128, P1129: Manifold absolute pressure (MAP) sensor
P0171, P0172: Fuel system
P0335, P0339, P0385, P0389: Crankshaft position (CKP) sensor A/B
P0506, P0507: Idle control system
P0340, P0344: Camshaft position (CMP) sensor
P0401, P0404, P0406, P2413: Exhaust Gas Recirculation (EGR) system

Note this freeze data:

Engine speed
Vehicle speed
Throttle position
CLV

Clear the DTC with the HDS.
Start the engine with no load (in neutral), then let it idle.
Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?

YES - Go to step 9.

NO - If the screen indicates PASSED, go to step 5. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, wait for several minutes, then recheck.

Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.

Does CYL1 MISFIRE. CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?

YES - Go to step 9.

NO - Go to step 6.

Test-drive the vehicle for several minutes in the range of the recorded freeze data.
Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?

YES - Go to step 9.

NO - If the screen indicates PASSED, go to step 8. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 6 and recheck.

Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.

Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE. And/or CYL6 MISFIRE show misfire counts?

YES - Go to step 9.

NO - Intermittent failure, system is OK at this time.

Turn the ignition switch OFF.
Check the fuel quality.

Is the quality good?

YES - Go to step 11.

NO - Drain the tank, and fill it with a known-good fuel, then go to step 20.

Inspect the spark plugs. If the spark plugs are fouled or worn, replace them.
Test-drive the vehicle for several minutes in the range of the recorded freeze data.
Check the CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE in the DATA LIST for 10 minutes with the HDS.

Does CYL1 MISFIRE, CYL2 MISFIRE, CYL3 MISFIRE, CYL4 MISFIRE, CYL5 MISFIRE, and/or CYL6 MISFIRE show misfire counts?

YES - Go to step 14.

NO - Go to step 20.

Check the fuel pressure.

Is the fuel pressure OK?

YES - Go to step 15.

N0 -

If the pressure is too high, replace the fuel pressure regulator, then go to step 20.
If the pressure is too low, check the fuel pump, the fuel feed pipe, and the fuel filter. If they are OK, replace the fuel pressure regulator, then go to step 20.

Turn the ignition switch OFF.

Remove the VTEC oil pressure switch (A), and install the special tools as shown, then install the VTEC oil pressure switch (A) in the pressure gauge adapter (B).

NOTE: Install the switch in the reverse order of removal with a new O-ring.

Reconnect the VTEC oil pressure switch 2P connector.
Start the engine. Hold the engine at 3,000 rpm with no load (in Park or neutral) until the radiator fan comes on.
Check the oil pressure at engine speeds of 1,000 and 2,000 rpm. Keep the measuring time as short as possible (less than 1 minute ) because the engine is running with no load.

Is the oil pressure below 49 kPa (0.5 kgf/sq. Cm, 7 psi)?

YES - Check for air in the fuel line, then go to step 20.

NO - Inspect the VTEC system, then go to step 20.

Turn the ignition switch ON (II).
Reset the ECM/PCM with the HDS.
Clear the CKP pattern with the HDS. See: Powertrain Management Computers and Control Systems Engine Control Module Testing and Inspection Programming and Relearning
Do the ECM/PCM idle learn procedure. See: Powertrain Management Computers and Control Systems Engine Control Module Testing and Inspection Programming and Relearning
Do the CKP pattern learn procedure. See: Powertrain Management Computers and Control Systems Engine Control Module Testing and Inspection Programming and Relearning
Test-drive the vehicle for several minutes in the range of the recorded freeze data.
Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P0301, P0302, P0303, P0304, P0305, or P0306 are indicated, check for poor connections or loose terminals at the ignition coil, the injector, and the PCM, then go to troubleshooting DTC P0301, P0302, P0303, P0304, P0305 or P0306. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - Go to step 27.

Monitor the OBD STATUS for DTC P0301, P0302, P0303, P0304, P0305, or P0306 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - Troubleshooting is complete.

NO - If the screen indicates FAILED, go to step 1 and recheck. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 25 and recheck.

Check fuel trims. If running on the rich side then do a valve adjustment when the engine is cold. You will find most of the exhaust valves are going to be tight. Good luck and let us know how it goes.

Misfiring could be due to various factors and the cost would depend on the amount of parts to be replaced. The most common parts that require attention would be the spark plugs.

You can continue to drive the vehicle but if it is misfiring badly, the catalytic converter might glow red hot while driving. If that occurs, it is not advisable to continue driving as it could damage the catalytic converter over extended periods.

Welcome to 2CarPros. It's not really good to drive with the misfires, especially if the CEL is flashing. The reason for this is that the misfires will cause unburned fuel to enter the catalytic converters and this can easily damage them to the point they have to be replaced.
Because this was a sudden thing I doubt it is spark plug failure as they seldom fail as a group. However if they have not been changed in a while it would be a good first thing to check. Next would be to check the power feed to the coils, look at the wiring harness that the coil wires go into and look for damage or rubbing. All of the coils are fed from one fuse but because the engine still runs the fuse is good. Another thing to try, if the CEL isn't flashing would be to clear the codes and see if they suddenly come back. It is very possible that they were caused by a cascade effect where one cylinder dropped out but it causes a "false code" on the cylinders around it in the firing order. If you get back the same cylinder codes ((the P0300 is because you have three cylinders (1, 4 and 6) reporting a misfire)) Then I would likely change the plugs and see if the codes are still present. If the scan tool you used can view live data it might also give a clue as to the problem, but only if it shows the misfire counts.

STEVE W. Is one of our best! Please let us know what you find. We are interested to see what it is.

When you did the tune up did you use OEM parts? cheap tune up parts can cause these issues. Here is a guid to help you do the job right.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

Please let us know what you find.

Good to hear, please use 2CarPros anytime we are here to help.

Cheers

Is this the v-6 with v-tec? If so I had a very similar problem on a customers car. His car would drive ok until you would try to accelerate hard then at about 3500 rpms it was like you were hitting a rev limiter. You have a similar car and codes. Can you tell me more about how the car runs and drives under normal and hard driving. His car turned out to be the v-tec soenoid.

Hi David,

Well as you probably know the 300 -306 codes are all misfire codes. The 1399 code I am not to familar with but have found a few places that indicate EGR Valve.
So try removing the vacuum line from it and see what happens or if you can remove it and clean it out.

And when was your last Tune Up?

Also will need more info on your vehicle.

For the vehicle year I need the Month and Year,
The Sub Model - EX, DX, LX
The Engine Size In Liters
Is it a Hybrid or not.

.

Good morning

Did you check the compression in the engine?

https://www.2carpros.com/articles/how-to-test-engine-compression

Wondering if the timing belt may be worn out.

https://www.2carpros.com/articles/how-a-timing-belt-works

Are there any other codes besides the misfire codes?

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Roy

Hi techwizard852,

Thank you for the donation.

For misfiring to be recorded, it might at times takes some driving before it is recorded and illuminates on the Check Engine Light.

The problem would not cause the vehicle to breakdown though it would affect the performance and fuel consumption.

As repair had been carried out, you would need to do some driving to confirm if it had been resolved. As vehicle is still under warranty, if the problem reoccurs, you can always get back to them.