I bought a used 2006 prius a couple years ago. The previous owner said the cat was stolen before, they had it replaced, and installed a cat shield. There is a consistent rattle during acceleration only when the gas engine kicks in. When idle or coasting there is no rattle. Im usually very light footed, but if i have to climb up a hill or speed up quickly, the rattle becomes much louder and more prevelant. Its always a consistent rattle, and during acceleration. The seller said the rattling is caused by the catalytic converter hitting the shield, and I took it to a mechanic who said it was fine. It passed smog check no problem. Online searches said there could be a bunch of reasons including breaks, clogged catalytic converter, engine gasket, spark plugs and etc.. Does anyone know where it's really from? Thank you.
I had a bad case of spark knock just about 6 weeks ago that sound of exhaust rattling is possible but it was bad spark knock sounded like a hand hammered wok factory on my engine or in it. Plugs made it go away. I think fake Denso were in it
