Quote:
Originally Posted by Clipdat
What about under throttle off vacuum deceleration? Also could it be perceivable then that there is a slight pulsing effect that draws a slight amount of exhaust gas back?
These are serious questions as I honestly don't know. It does however seem unlikely that the bits of the cat would make it all the way back up and into the engine.
It's hard to tell by looking at the photo, but the dislodged cat still seems to be mostly intact. So maybe those bits are from something else besides the failed cat?
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I've heard many explanations as to why the pieces get sucked into the engine over the years, but can't say for certain.
What I can say is that engine failure from a precat collapse is a thing that happens, and is usually the result of unburnt fuel going into the exhaust system from a rich tune. It's a common problem with the Nissan QR25, which I had in a 2003 Sentra Spec V. In this case, if not a manufacturer defect, it could have either been from the engine relearning and dumping too much fuel into the engine, or a tune on the car which was intended to make pops and crackle noises (done by dumping fuel into the exhaust). Also plenty of other possibilities that my limited experience can't identify, since none of us seem to be mechanics around here.
https://www.b15sentra.net/forums/sho...d.php?t=135241
https://www.bobistheoilguy.com/forum...39188&page=all
https://www.maseratilife.com/threads...21/#post-23243
https://www.caradvice.com.au/687702/...p-crackle-pop/