Exhaust fumes in cabin when A/C on recirculate

Raw car exhaust is pretty stinky. It's normal to be able to detect that smell around and in cars that don't have catalytic converters. Many people have forgotten (or are young enough to have never known) how stinky cars were in the 1970s and earlier.

Just because you can smell it doesn't mean you're getting poisoned- the nose is sensitive but it doesn't exactly give a precision readout.

So I'm not saying you don't have an exhaust leak... just that you don't need one to get bad smells in the cabin of a car with no cat.

 

Recirc still allows outside air. Just not as much as recirc off. If you get caught in traffic behind an old diesel you will smell it.

The Prius v wagon has a special button to temporarily close off the remaining recirc intake air.

Since you are apparently getting your own raw exhaust, I would fix it the right way with a Walker 16337 for a few hundred. I have seen it work for years as have others.

Napa 16337 Catalytic Converter? Check Engine Free? | PriusChat

 

A cat is not an air fresher that masks the hydrocarbons. It eliminates the hydrocarbons when warmed up by burning them.

It is also likely your engine is not burning the optimum air fuel mixture without a proper O2 sensor response downstream of the cat.

Everyone else is dramatically reducing the pollution - it's your time now.

 

The only difference between recirc and fresh in this instance is that the latter will much more effectively replace the cabin air with clean air. It comes in just in front of the windshield, and on top, so far from the exhaust system. Old cars, pre-emissions controls, didn't stink of exhaust, recirc or fresh, as long as they were in working order and moving. This doesn't sound like a mystery, it sounds like an exhaust leak. Maybe holes were poked through the cat when it was gutted, maybe it wasn't reinstalled properly, maybe that and there are holes in the floor, whatever. Since the cat is gutted just put a smoke generator in the tail pipe and see where the smoke comes out upstream, then fix it.

 

Out of morbid curiosity, why did you gut the catalytic converter in the first place? This is a Prius, so it isn't going to result in a significant improvement in performance, and as you found out, there can be issues when one messes with the exhaust system. It won't even "roll coal" like a modified diesel, just stink a lot and smoke a little, which if it is an anti-environmental message, is a really tepid one. The action itself is a Federal crime subject to penalty, but not one likely to be discovered in a state without mandatory inspections. If the car stinks inside presumably it stinks even worse behind it. That is likely to mightily piss off any driver unfortunate enough to be behind your car in a long slow line, and many times more so in a tunnel.

 

How many miles on the odometer?

 

How many miles a week is it driven? Valvoline Restore and Protect claims that it cleans varnish and other gunk off, but it may take four oil changes for that to become apparent. Sounds like snake oil but that is a reputable company, so maybe it is true. We don't drive many miles anymore, so even though I'm trying this oil I don't expect to see any improvement in oil consumption (it burns a little bit) for years. However, it might keep it from getting worse. If a car was driven say 15k miles a year with 5k interval oil changes improvement should be much faster, by their claim, in a year and four months.

Who knows, maybe after it fixes your car's oil consumption problem it will grow back the catalyst!

 

ASRDogman has tried it without success as have several youtube guys. One of those guys, DIY Dave, has tried about 30 products and methods on a Toyota with low tension rings and only saw temporary improvement with B12, but that did not last.

 

I suspect that even if VRP works well on most cars it might not be great on a Prius because it is probably optimized for engines that get up to temperature and then stay there for a long time. If I could locate the protocol which corresponds to "sequence iiih testing" it would help, since at this time I'm not sure what the conditions are for that test. My best guess, and it is just that, is that they start a motor and then run it nonstop, perhaps under slightly different loads at various times, until it reaches "100k miles" of use, and then they tear it down and inspect it. Except on long trips, which we only rarely take, our car does mostly short trips, and I suspect that it is below fully warmed up for a lot of that. That is probably pretty different than those test conditions.

Still, even if it cannot free rings that are already stuck (no restore) perhaps it can keep rings from getting worse (some protect).

 

That is 5k miles in 10 weeks, 4 oil changes in less than a year (approximately, with 5k mile oil changes). If VRP is ever going to work in a Prius, this may be the one.