I’m experiencing a strange issue with my car. Everything runs fine during normal driving, but if I go full throttle—say a quick pull from 35 to 100 mph—the engine starts idling very rough when I slow down, and the exhaust pops like crazy.



When I got home and checked under the hood, I immediately heard a loud vacuum leak. Turns out the PCV hose on the passenger side had popped off the assembly at the back. No big deal—I figured it had cracked like most Jaguar hoses. I ordered a new one ($90), installed it, and took the car for a test drive.



After another full-throttle run, the exact same thing happened. As long as I stay out of full throttle, everything is rock solid.



What could be causing this hose to pop off only under hard acceleration? Both new and annoyingly, the old hose clicks into place, locks securely, and resists being pulled off by hand. The male fitting is round and doesn’t seem to be damaged. I’ve searched the forums but haven’t found anyone mentioning this issue. Has anyone else dealt with this

 

Long shot?
Do you think maybe the engine is moving too much under full throttle? Like an engine and/or transmission mount allowing too much movement?
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I have thought of that but the hose and the engine would shift together. Since the hose / throttle body / PCV mount are all on the engine.

 

Good point! I had not thought of that.
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When you go full throttle the supercharger bypass valve closes and the PCV system is under boost which is blowing this hose off. Are you sure the hose is fully seating on the male end?