DH manual misfire P0300/P0302/P0308 - PCM update?

[Zbychersky]

Hi,

Last time received couple of times check engine during full acceleration on 4th gear (it happend before and after tune so I don’t think it’s down to the tune).

===OBD2_PCM DTC P0300-P===
Code: P0300 - Random Misfire Detected

Status (-50):
 - Pending - malfunction is expected to be confirmed

Module: On Board Diagnostic II (PCM)

Diagnostic Trouble Code details

Random Misfire Detected

This DTC may be caused by :

Ignition System

Fuel System

Low Fuel Warning

Blocked kinked or crushed fuel lines

Fuel contaminated

Evaporative emission control system malfunction

EGR system fault.

Base engine fault

Check for any other codes that may cause a misfire.

===END OBD2_PCM DTC P0300-P===

===OBD2_PCM DTC P0302-P===
Code: P0302 - Cylinder 2 Misfire Detected.

Status (-50):
 - Pending - malfunction is expected to be confirmed

Module: On Board Diagnostic II (PCM)

Diagnostic Trouble Code details

Cylinder 2 Misfire Detected.

Ignition System

Fuel System

This DTC may be caused by :

Blocked kinked or crushed fuel lines

Fuel contaminated

Evaporative emission control system malfunction

EGR system fault.

Base engine fault

Check for any other codes that may cause a misfire.

===END OBD2_PCM DTC P0302-P===

===PCM DTC P0300:00-64===
Code: P0300 - Random/Multiple Cylinder Misfire Detected

Status (-64):
 - DTC Maturing - Intermittent at Time of Request
 - Malfunction Indicator Lamp is Off for this DTC
 - Test not complete

Module: Powertrain Control Module

 Freeze Frame  #1:

 Freeze Frame  #2:
-EVENT_TIME: 75168150 s (Sun Jun 21 19:04:11 2026) - Event time
-TOTAL_DISTANCE: 19544 km - Total Distance
-FUELSYS: OL - Drive  - Fuel System Status (Open/Closed Loop)
-LOAD: 98.43 % - Calculated Load Value
-ECT: 89 °C - Engine coolant temperature
-ECT: 89 °C - Engine coolant temperature
-SHRTFT1: 0.00 % - Short term fuel trim 1
-LONGFT1: -0.78 % - Long term fuel trim 1
-SHRTFT2: 0.00 % - Short term fuel trim 2
-LONGFT2: 3.91 % - Long term fuel trim 2
-MAP: 95.0 kPa - Manifold absolute pressure sensor
-RPM: 7081 1/min - Engine Revolutions Per Minute
-VSS: 202.0 km/h - Vehicle Speed
-VSS: 202.0 km/h - Vehicle Speed
-SPARKADV: 22.50 ° - Spark Advance
-IAT: 26 °C - Intake Air Temperature
-RUNTM: 1170 s - Time Since Engine Start
-RUNTM: 1170 s - Engine Run Time
-FRP: 18980.0 kPa - Fuel Rail Pressure
-EVAP_PCT: 95.69 % - Commanded Evaporative Purge
-FLI: 47.06 % - Fuel Level
-BARO: 99.0 kPa - Barometric pressure
-BARO: 99.0 kPa - Barometric pressure
-VPWR: 14.02 V - Control Module Voltage
-VPWR: 14.02 V - Control Module Voltage
-TP_REL: 83.14 % - Relative Throttle Position
-TAC_PCT: 92.16 % - Commanded Throttle Actuator Control
===END PCM DTC P0300:00-64===

===PCM DTC P0302:00-64===
Code: P0302 - Cylinder 2 Misfire Detected

Status (-64):
 - DTC Maturing - Intermittent at Time of Request
 - Malfunction Indicator Lamp is Off for this DTC
 - Test not complete

Module: Powertrain Control Module

 Freeze Frame  #1:

 Freeze Frame  #2:
-EVENT_TIME: 75168150 s (Sun Jun 21 19:04:11 2026) - Event time
-TOTAL_DISTANCE: 19544 km - Total Distance
-FUELSYS: OL - Drive  - Fuel System Status (Open/Closed Loop)
-LOAD: 98.43 % - Calculated Load Value
-ECT: 89 °C - Engine coolant temperature
-ECT: 89 °C - Engine coolant temperature
-SHRTFT1: 0.00 % - Short term fuel trim 1
-LONGFT1: -0.78 % - Long term fuel trim 1
-SHRTFT2: 0.00 % - Short term fuel trim 2
-LONGFT2: 3.91 % - Long term fuel trim 2
-MAP: 95.0 kPa - Manifold absolute pressure sensor
-RPM: 7081 1/min - Engine Revolutions Per Minute
-VSS: 202.0 km/h - Vehicle Speed
-VSS: 202.0 km/h - Vehicle Speed
-SPARKADV: 22.50 ° - Spark Advance
-IAT: 26 °C - Intake Air Temperature
-RUNTM: 1170 s - Time Since Engine Start
-RUNTM: 1170 s - Engine Run Time
-FRP: 18980.0 kPa - Fuel Rail Pressure
-EVAP_PCT: 95.69 % - Commanded Evaporative Purge
-FLI: 47.06 % - Fuel Level
-BARO: 99.0 kPa - Barometric pressure
-BARO: 99.0 kPa - Barometric pressure
-VPWR: 14.02 V - Control Module Voltage
-VPWR: 14.02 V - Control Module Voltage
-TP_REL: 83.14 % - Relative Throttle Position
-TAC_PCT: 92.16 % - Commanded Throttle Actuator Control
===END PCM DTC P0302:00-64===

===PCM DTC P0308:00-64===
Code: P0308 - Cylinder 8 Misfire Detected

Status (-64):
 - DTC Maturing - Intermittent at Time of Request
 - Malfunction Indicator Lamp is Off for this DTC
 - Test not complete

Module: Powertrain Control Module

 Freeze Frame  #1:

 Freeze Frame  #2:
-EVENT_TIME: 75168150 s (Sun Jun 21 19:04:11 2026) - Event time
-TOTAL_DISTANCE: 19544 km - Total Distance
-FUELSYS: OL - Drive  - Fuel System Status (Open/Closed Loop)
-LOAD: 98.43 % - Calculated Load Value
-ECT: 89 °C - Engine coolant temperature
-ECT: 89 °C - Engine coolant temperature
-SHRTFT1: 0.00 % - Short term fuel trim 1
-LONGFT1: -0.78 % - Long term fuel trim 1
-SHRTFT2: 0.00 % - Short term fuel trim 2
-LONGFT2: 3.91 % - Long term fuel trim 2
-MAP: 95.0 kPa - Manifold absolute pressure sensor
-RPM: 7081 1/min - Engine Revolutions Per Minute
-VSS: 202.0 km/h - Vehicle Speed
-VSS: 202.0 km/h - Vehicle Speed
-SPARKADV: 22.50 ° - Spark Advance
-IAT: 26 °C - Intake Air Temperature
-RUNTM: 1170 s - Time Since Engine Start
-RUNTM: 1170 s - Engine Run Time
-FRP: 18980.0 kPa - Fuel Rail Pressure
-EVAP_PCT: 95.69 % - Commanded Evaporative Purge
-FLI: 47.06 % - Fuel Level
-BARO: 99.0 kPa - Barometric pressure
-BARO: 99.0 kPa - Barometric pressure
-VPWR: 14.02 V - Control Module Voltage
-VPWR: 14.02 V - Control Module Voltage
-TP_REL: 83.14 % - Relative Throttle Position
-TAC_PCT: 92.16 % - Commanded Throttle Actuator Control
===END PCM DTC P0308:00-64===

I found this technical service bulletin SSM 53215, so I carried out the ‘Forscan Misfire Monitor Profile Correction Learn’ procedure. I haven’t had a chance to check yet whether it helped, but I’m wondering if there’s a PCM update related to this issue? As far as I know, the tuner hasn’t altered the knock detection strategy.

Here’s some information about my PCM:

• PCM Part Number: PR3A-12A650-SC
• Calibration Level: PR3A-12A650-SC
• Strategy: RR3A-14C204-AVH
• Hardware: PR3A-12B684-MC

Could someone please check if there have been any updates relating to misfire monitoring?

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[Yamazuki]

Just returned home from roughly a 2000 mile trip out to Colorado and back. Had misfire codes pop up on several occasions while in Colorado. However it was usually a P0304 code with the last occurrence being both P0303 and P0304. I find that I can pretty consistently trigger the engine light to flash if I use a low gear and hold RPM's steady (not accelerating or decelerating) in the 3000 to 5000 range.
Dealer will be getting a call tomorrow.