So my Nissan emits a loud (way louder than normal) “vroom” when I start it up and then idles back. Also, sometimes the tach needle jumps high and then falls, sometimes almost seems like the car might turn off. I have a knock sensor code on and nothing else. I was due for state inspection and the guy told me that my exhaust was warped and said that it was too loud and I will fail the inspection (I think he meant on the noise level as he did not do any diagnostics, I am in Mass so we have a computer check) and quoted a price of $500 to fix the exhaust claiming that my car was made under “California std” and had multiple parts to my cc and exhaust. Is exhaust the real problem? Should I fix it?
Take it to another garage. May just need an exhaust gasket.