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2015 Ford F-150 P0300 Fault: Misfire in Cylinders 2 and 5 Despite Replaced Injectors, Intake Gaskets, and Crank Sensor

Model: 4.3 Fault Code: P0300 Posted: 2009-01-23 23:27

Vehicle: 2015 Ford F-150 Fault Code: P0300 (Random/Multiple Cylinder Misfire) Issue Summary: The vehicle exhibits a P0300 code indicating misfires in cylinders 2 and 5. All major components have been replaced including fuel injectors, intake gaskets, crankshaft position sensor, and the engine has undergone a full tune-up. Compression tests show normal readings, and the engine runs smoothly under load and during driving conditions. Symptoms: The MIL (Malfunction Indicator Lamp) flashes only when idling at or above 1900 RPM—commonly observed on downhill highways or when the vehicle is stationary with the throttle held at high RPM. No misfire is detected in other cylinders, yet the P0300 code persists. Fuel pressure checks have been performed and show no abnormalities. Despite these efforts, the engine continues to display intermittent misfires specifically in cylinders 2 and 5. Current Status: The vehicle runs smoothly under normal driving conditions but still shows a flashing MIL light under specific high-RPM idle scenarios. No clear cause has been identified after replacing all suspect components.

Related fault codes
P0300
Comments (5)
Anonymous 2009-01-24 07:17

The issue may stem from a worn distributor or an out-of-spec camshaft position sensor. On this engine, the distributor is non-adjustable. Using a scan tool to monitor the camshaft position angle (in degrees) can help determine if it's outside the acceptable range of ±4 degrees. If the reading exceeds this threshold, replacement of the distributor may be necessary.

Anonymous 2009-01-24 20:57

Thank you—I'll try checking the camshaft position with a scan tool and verify the distributor angle.

Anonymous 2009-01-26 22:45

Replaced the distributor, but no improvement. The camshaft position reading is now at 2 degrees. When holding the brake in drive at 2000 RPM, tires begin to smoke on pavement. The scan tool still shows misfires in cylinders 2 and 5. The MIL light remains active. Despite this, the engine runs smoothly under normal conditions. I'm unable to understand why this specific issue persists.

Anonymous 2009-01-27 05:50

Did you check the camshaft position before replacing the distributor? A reading of 2 degrees is acceptable as long as it remains stable during acceleration and throttle input. If the angle was already at 2 degrees prior to replacement, then no change would be needed. Additionally, ensure all listed components were properly replaced. Consider installing a vacuum gauge to monitor vacuum fluctuations during misfire events—any fluttering could indicate intake or valve train issues.

Anonymous 2009-01-29 22:53

Relearned the sensors, vacuum readings are stable, and all parts have been ruled out. The vehicle runs fine under normal conditions, but the MIL light still flashes intermittently when operating at high RPMs (1900+). This issue appears to have existed since the truck was purchased—indicating it may be a known persistent problem that previous owners were unable to resolve. Thank you for your insight and support.