I check the air pump and no noise coming from there. How do I test the camshaft sensor sensor? By replacing it? I went to an indy shop and explained what happened. The guy said that the camshaft adjuster is the culprit. I mentioned the chain tensioner and he was 99% sure is the camshaft adjuster. It seems to be a job as big as replacing the chain. He said 5 hours or so of work. What do you guys think? what's your experience with this adjuster?