what is the timing?

Thank you so much. I was a heavy line mechanic for over 55 years and when these things became computerized? and all that? you lift the hood anymore and cannot even find the engine? I gave up. I figured it was the "Timing" but then there are so many different sensors etc anymore and without any tools to check it you have to be at the mercy of someone else! and that hurts when you are a seasoned mechanic. Thank you for your reply though I really do appreciate it.