2013 Yukon Denali Hybrid. Driving the other day all of a sudden the engine started running rough and check engine light started flashing. I did not hear any noises at this time. I continued to drive. It did continue to go into Auto Stop as normal, but every time the engine would start it would soon show the check engine. The code is P0306 and comes back every time I clear it. Later I started hearing a clicking on acceleration and later at idle also. I pulled the plug on #6 cylinder and swapped it with #4. Still had miss. I then swapped plug wire and still had miss. I went a got a spark tester and sure enough it showed a miss when connected to #6. I borrowed a coil from a friend, but it was the flat type off a Tahoe and mine is round if that makes a difference. I plugged in the coil with much contortion-ism to get around hybrid box and wires and still had miss and some clicking or knock. I put spark tester back on the borrowed coil and it has an occasional fading of the spark. So the questions are is the flat coil any different than the round type of coil. Should I borrow another coil and try it before assuming a collapsed lifter? Why would a collapsed lifter prevent the spark from being consistent? Can the miss cause a noise in the intake and exhaust system that sounds like a lifter? Can I drive it like this until I can figure out the issue? I thought the Auto Stop wasn't suppose to come on when the check engine light comes on. Any other suggestions? How do I get the big bracket covering the #8 and #6 coils off?

 

Don;t drive it you will burn up the catalytic converter. do a compression test and check the spark plug

loose wires check the 12volt battery cable make sure the connections are clean and sung

the spark cable could be bad or high resistance

 

I swapped the plugs and wires. Why would loose battery cable only effect 1 cylinder? So the occasional unexploded fuel mixture will destroy the converter? So it does make noise in the exhaust with a missing cylinder? Maybe not stuck lifter?