Maybe but I doubt it.

It would be my #1 suspect.

 

Thanks everyone for your answers. The source of hissing turned out to be the PCV pipe. It's especially audible at idle. I blew this hose with a smoke generator towards the motor, there are no leaks. I noticed that it sucks on the oil filler cap at idle, there is a decent vacuum in the crankcase. I suspect that pcv is out of order.

 

nah, the pcv is just a right angled fitting with a check valve. You need to find where the smoke comes out when you pump the smoke in with the smoke tester. O-rings on any vacuum lines including on the oil filler cap can do it. Look for the smoke!!

 

The PCV system on the V6 is a bit different than most vehicles, and is open at idle. On most other vehicles, it's is closed at idle. I found the PCV valve clogged on my '02 V6 and it caused some issues. Details here, see post #21:

https://www.jaguarforums.com/forum/s...rly-v6-264531/

Is your PCV valve located at the back of the engine, or under the intake plenum? I think it functions the same regardless of position.

 

This is the point that no smoke leaks were noticed, everything is hermetically sealed.

 

Are you sure? As far as I know, at idle and high vacuum in the intake manifold, the valve should be opened minimally.
If I understood correctly from your topic, then the crankcase ventilation is designed in such a way that the air after the air filter is sucked through a large branch (pipes in the valve covers) into the crankcase, and then, together with crankcase gases, enters the intake manifold behind the throttle valve.

 

I am willing to stake your reputation on it.

I did a lot of headscratching on this very subject a few months ago. I played with a brand new PCV valve to confirm how the system works. I’m not a climate change researcher and was not trying to reach a predetermined conclusion.

And yes indeed, this PCV system works opposite of most other vehicles. The PCV valve in this case is basically just a check valve to prevent reverse flow, such as with a backfire. Under normal conditions, it is always open.

See post #25 at the previous link to see how I tested this theory.

In my case, it didn’t immediately fix everything (still had a bad coil at the time) but it definitely improved an erratic idle.

Buy a new valve and play with it yourself to see.

Your smoke test? It’s great for finding external leaks. But if your PCV valve is clogged, a smoke test won’t find that. My PCV valve was maybe 90% clogged. It would still let some smoke through when I tested if air could get through. Some did, but not enough for normal engine operation.

Definitely check out your PCV system and replace the valve if needed. Carefully check the lines, too. I found mine in poor condition. If cracked, unmetered air will be drawn into the induction system and possibly set some codes. Just be aware a clogged PCV valve may only be part of the equation and other faults may still be active.

 

it expects unmetered air from the crankcase at all times, valve is always open. this is the same way the v8 does it with but with an oil separator valve instead of mesh inside the valve cover

get the propane and watch how your fuel trims react. smoke test is not reliable

 

Slight correction, at least on the V6. It's metered air passing through the crankcase. Clean air, after the filter and MAF sensor, is drawn off just upstream of the throttle body. This clean metered air passes through the crankcase, collects dirty fumes, passes through the PCV valve, and is drawn back into the intake immediately after the throttle body.

Respectfully submitted

 

Agreed - a smoke test can show the presence of an air leak ... but can also fail to show leaks

Equally, it's fairly easy to miss a leak using such as propane - because you may fail to spray in the right place or may somehow not be looking at the trims just at the moment they change (it happens).

Whatever you do, don't assume you'll hear a leak, though. Occasionally you will but it's usually a BIG (from the car's viewpoint) leak.

 

The battery is new, I personally changed it half a year ago. Yes, all the pipes were in place. I blew more than once, both the entire system and individual components (pcv, vacuum booster)

 

Today the master found a broken stud on the exhaust manifold and traces of gas leakage. As one of the forum members wrote, could this be a problem? The question is how now to replace the gaskets and the broken stud there. I don't want to take out the motor(

 

You may be able to see its effect in the fuel trims - worth posting the numbers here anyway. Hot engine. Parked. At idle & then rev to about 2500. Don't try to get near 3000 or the rev limitter will cut in.

 

yes it was me. I had a leak at the exhaust round flange above the converter

 

[QUOTE=JagV8;2625210] Спасибо, проверю

 

Yes! An exhaust leak leads to high O2 readings. As the lambda sensors read the amount of oxygen in the exhaust to determine optimal mixture adjustment they will be getting confused and adjusting incorrectly. You cannot accurately tune a car with an exhaust leak.
Fix the exhaust leak and your problem may disappear.😃

 

If anyone is wondering what an oil separator looks like with pcv.

 

Did you fix your car?

 

Not yet. PCV, I still ordered a new one, I also ordered exhaust manifold gaskets, it remains only to find a way to remove them)