GMC Acadia 2009 P0300 Misfire: Hesitation Between 80-100km/h at Less Than 2000 RPM
My 2009 GMC Acadia hesitates between 80 and 100 km/h on the highway, occurring only below 2000 RPM. The issue does not occur above this speed. The OBD-II diagnostic code displayed is P0300 (Random/Multiple Cylinder Misfire). I'm trying to determine whether this is caused by ignition, fuel delivery, or a mechanical problem. Any insights or troubleshooting steps would be greatly appreciated.
P0300 - Is it ignition, fuel, or mechanical? Yes, that's correct. Diagnostic testing is required to pinpoint the root cause. Check for any additional fault codes. Use an OBD2 scanner to review fuel trims, ECT (Engine Coolant Temperature), MAP (Manifold Absolute Pressure), and oxygen sensor readings. Also ensure the vehicle is stock — modifications could influence misfire behavior.