Hi all, 15 Yukon SLT (94000 miles) here
So I had a misfire code P300 and engine light blinking late December 18. Done a tune up (replaced all sparks and wires) and everything was fine until a few days ago. Didn't feel any lose of power, vibrations and etc.
Got another misfire code, this time P0305 (cylinder #5) a few weeks back. Mechanic looked into it and couldn't reproduce. Had an engine carbon clean up. Again no lose of power, vibration poor fuel economy and so on.
Couple of days ago got another misfire P0305. Called the mechanics and he suggested a compression test. Not sure if needed as no other signs are apparent. He also start speaking (worst case) about taking the cylinder out to be inspected and replacing AFM lifters.
I've looked into mode 6 on my OBD scanner as saw that cylinders 1,3,5,7 all have misfires, though below the threshold so no codes or lights. Cylinder #5 had count of 78 misfires and the rest (1,3,7) around the 1-5 (thats after a 2hr drive)
What I found weird is that the AFM cylinders (2,4,6,8) had no misfires. Aren't those the ones with the lifters?
I've replaced the coil of cylinder 1 with 5 and got the same results (higher counts of misfires on 5) so don't think that is the problem.
Anyone encounter the same issue? How was it solve? Any suggestions for self diagnostics before its heading back to the a shop?
Thanks