I've been having this issue for a while. Basically I keep having 10-20 misfires on cylinders 3,4,5 (Northstar V8). The other cylinders have 0 or 1 misfires. They seem to happen at high load. I've tried combinations of new OEM spark plugs and coils, but nothing really changed.
I was also looking at my Long Term Fuel Trims and at idle, They hover between +9% and +11%. When I'm driving at highway speeds or have the pedal pushed down, the long term trims go down to 0 and +5%
I then changed the MAF sensor with a Delphi brand. My throttle response did improve, but I still have the misfires.
Is it the fuel injectors? I looked for vacuum leaks in the obvious spots, but found nothing.
I was also looking at my Long Term Fuel Trims and at idle, They hover between +9% and +11%. When I'm driving at highway speeds or have the pedal pushed down, the long term trims go down to 0 and +5%
I then changed the MAF sensor with a Delphi brand. My throttle response did improve, but I still have the misfires.
Is it the fuel injectors? I looked for vacuum leaks in the obvious spots, but found nothing.