I got a 2003 SE Auto last year. At first, I felt a kind of vibration when stopped at traffic light. Went to dealer, I was told because of new car. After a few months, still the same problem. Went to dealer again, an experienced technician checked and said the timing degree is 2 degrees less than normal(15 degrees). He adjusted and I could feel much better at once. Yesterday, I got the car checked again, and there was 1 degree less. The technician adjusted it to 16 degrees and said the car would be more powerful. I don't know why and how. Is this a severe problem? Why did this happen again and again? Thanks a lot.

 

The ECM could be automatically adjusting for low octane fuel. What brand and grade of gasoline are you using? The spec is 15 degrees BTDC at idle. I am certain that bad knock could/would cause the ECM to retard the timing . . . It is also cool that your tech bumped your base timing up a degree or two, that is supposed to give you more power.