2006 Nissan Pathfinder P0300 Misfire Diagnosis: Bank 2 Only, No Spark on Bank 1
After driving approximately 30 minutes, my 2006 Nissan Pathfinder began experiencing intermittent studdering. It then ran normally for a few miles on the interstate before developing a persistent misfire with the SES light flashing. I replaced the battery three weeks ago and have since performed several diagnostics: spark plugs were changed, coil packs are confirmed operational through individual testing, fuel injectors show proper opening and closing, and oxygen sensors exhibit balanced readings. The engine appears to be running only on Bank 2. When any coil plug is removed from Bank 1, no change in performance occurs; however, when a plug is pulled from Bank 2, the engine immediately stalls. The only fault code detected is P0300 (Random/Multiple Cylinder Misfire). I am seeking advice on how to further diagnose this issue, especially given that Bank 1 shows no spark and Bank 2 causes complete loss of power upon ignition. Could this be a fuel delivery problem? A faulty ignition system in Bank 2? Or is there another underlying cause despite the confirmed coil functionality?
Perform a fuel pressure test and conduct a KOEO (Key On, Engine Off) observation to check for fuel pressure drop—any drop of X psi within 3–5 minutes indicates potential fuel delivery issues. As a precaution, inspect engine oil for signs of gasoline contamination. Check the spark plugs on Bank 1 to ensure they are firing properly—the symptoms suggest a possible lack of spark. How do you know the coil packs are fully operational? Spark testing should be performed directly at the plug end outside the engine. Always verify spark presence under real conditions. Did you use the correct spark plug type for your 2006 Nissan Pathfinder? What condition did the old plugs show—wet, dry, or black? Note: Bank 1 is reported as RS (Rear Side) bank.