I've no idea the state of the valve closest to the turbo as I didn't check it. Am fitting them Wednesday, so will report back then. Cheers!
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Guess what.....
I've just had the exact same problem with my car.
Loud whoosh noise when boost comes in and 21in/hg at idle without any idling issues. It started as a quiet whoosh yesterday and by today it was quite loud with a large drop in boost pressure.
So when the rain stopped I dashed out to find the problem.
I removed the air filter box completely (by undoing the pipe from the MAF) and blew into the intake pipe sealing my face around it to create a little flow. I could hear the air escaping, so I felt along the intake rubber piping starting at the top of the turbo. And that is where the problem was.
The top turbo hose had split.
https://i.imgur.com/WtYxArFl.jpg
https://i.imgur.com/DBj6yzZl.jpg
Fortunately I had a bit of spare hose, so problem diagnosed and sorted within 10 minutes.
If you haven't pressure tested yet then it maybe worth trying. Doesn't have to be an elaborate pressure testing kit, just blowing into it will work. Chances are yours is probably something similar if it is a loud whooshing noise.
.....and SORTED!! Mine was a split throttle body hose, where the idle control branches off - massive split, not visible from the topside!!
One of the NRV's was shot, but the other was ok, though I obviously replaced both.
It now boosts to max 16psi (unbelieivable). Many thanks for all the help anyway!!
Stuart.
Nice one!
That's where another lad on here had one split, must be a weak point then.
Enjoy :D :D
it's all good, except I'm still getting the dreaded 0172 code which was something I didn't elaborate on for this thread. I'm suspecting it's possibly the infamous elbow on the inlet manifold adjacent to the P|S pump. It can't be much else as I've replaced the MAF, both 02 sensors, all the vac lines and hoses except the elbow (which itself was replaced in 2012 as part of a PCV system change). It will only throw the code usually when the engine is cold. If you then clear the code and disconnect the battery for 5 mins with engine up to temp the code won't reappear until the next time the engine is run from cold. When the code appears, it limits boost to around 10psi (before it was 6-7psi, before the split throttle body hose was replaced).
Spraying around the vac elbow with carb cleaner/silicone spray does not make any difference with the engine running and I'd have thought a split one would make the engine hunt or idle quicker when something is sprayed near it!??! I do have a slight exhaust leak on the turbo manifold where I fitted a 3" downpipe, but the code was appearing well before that was fitted anyway.
Well I finally sorted the 0172 after months of complacency and assumption (the Mother of all feck ups of course)...
I had the local indy fit two new Lambda Sensors a good few months back and it started throwing combined 0131 & 0172 codes. I had already fitted a new Bosch MAF previously so I didn't look at that for the possible 0172 cause. I also ASSUMED that the new o2 Sensors weren't at fault, so decided to start chasing ghosts. Smoke test and all new vac/turbo pipes later cured a whole host of other bugs(as per this thread), but the 131 & 172 persisted. So, I decided - finally - to change the front o2 sensor and went to my local GSF parts place to get one.
I had asked for a Bosch and they said it would be either that or NTK, so when I went to pick it up a day later, surprise, surprise, there's a Beru sensor awaiting me. Not too happy, I accepted it and went off to fit it. On taking the old one off (fitted just a few months previous) I found it similarly to be a Beru and was a bit miffed to say the least. I decided to fit the new Beru and no surprises, similarly it threw a 131 just 5 miles of driving.
Severely pissed off, I phoned my local Euro Parts dealer (stuff GSF) and ordered a Bosch and specifically said Bosch and nothing else. I fitted it today and after a 50 mile drive no codes and all is good - better mpg, better performance and all is happy!
In conclusion: Beru Sensors it turns out (after chasing a few old threads around various car forums) have a different impedance to Bosch ones and are not fit for purpose in a Bosch system. NTK ones imo/experience are hit and miss and can work, but are not as good as Bosch. Beru though, well avoid unless you drive something French (apparently ��)....
Glad you've got it sorted, now you can really enjoy your Volvo.