04 mdx, 260,000 m
engine code says miss on all cylinders. Shop says it needs a valve adjustment. Never heard of valves causing code. Can valve adjustment cause engine code and would it be a miss on all cylinders?

 

More likely than not, you have a bad coil pack

 

260K miles it certainly can be valves, the exhaust tighten and the intake loosen over time. I recommend doing it every 105K miles