The issue has just come up in the past week.. It is a light shaking/vibration when I come to a stop. Exaggerated it would seem as though the truck was misfiring and wanting to stall, but it is only a very minor shake and vibration with the same symptoms of what would cause my Yukon to break down if it were to get worse. It is only minor now but I don't want it to progress, but I may actually need it to progress so that diagnosing it would be easier. It has also caused my check engine light to come on 0420 and 0430 Low efficiency in the left and right catalityc converters. I have been told that Cat's dont go bad on their own and it's the engine that make these suckers plug up so I am eliminating possible culprits.
I have been advised by the guys at a Chevy dealership that doing there engine flush kind of like a SeaFoam treatment for $130 and would take an hour to clean out the engine's intake and combustion and cat system. I forget what is was called but they said it is about 70% effective in fixing issues such as mine.
But what if it is the coil that is causing the misfire and all subsequent cat problems and vibration.. Is there a way to test a coil?
I cannot pull a plug wire while the engine is running because the vibration is so minor that I wouldn't notice which one could be the problem..
Also I have 220k on the engine but it has benn well maintained and never been 4-wheeling. Although I do tow a 26' Center Console fishing boat but I always use 4x4 low coming up the ramp for 2 reasons. One to minimize stress on the rearend and also to get the front end some use now and then..
---------- Post added at 10:13 PM ---------- Previous post was at 10:10 PM ----------
Also, I bought the truck with 170k miles on it and I have no Idea if the 02 sensor has ever been changed? Would that also be a possible candidate for this issue?
