I'm trying to help out a friend with a 2001 Camry LE. The check engine light is on, and she was told the timing was the problem after running diagnostics. They wanted $500 for a tune up. I thought that was a bit absurd. Engine runs rough. What do I need to do to correct the timing problem, and how? Adjusting the timing on my 69 Camaro is easy, but I'm not familiar with "modern" engines.