Technical Stilo multijet 115bhp wastegate question

[philomangan]

Hi guys, ex Fiat mechanic looking for help with this, Im trying to find out what pressure the wastegate starts to open on a stilo multijet 115bhp. My car started to feel a tiny bit slugish about a month ago and when I investegated a bit further I realised it was easy to open the wastegate by hand (not normal on petrol engined turbo cars) so I stuck a midivac on it to test it. Usually if you test a waste gate its set to a pre determined opening pressure by a spring acting on a diafram and was expecting a reading of about 0.8ish bar but as soon as I started to apply the vacume the wastegate started to open. Ive gone through the usuall EGR stuff, blocking it off and what not and that is clean and working perfect so it aint that. It got an air flow meter for a completely different problem about 6 months ago so Im quite confident it aint that. Now dont get me wrong it still makes boost but I feel it lacks the go it had when I got it at first. So if anyone could tell me the opening pressure or tell me if they had to replace the wastegate because of a simular problem would be much appriciated.

 

[john55]

You dont have a wastegate. You have a variable vane turbo. You either get power or none on vv turbos. there is no inbetween.

 

[philomangan]

Ok, so whats the wastegate type looking thing bolted on the side of my turbo then. I just ask because I have lots of expirence on subaru world rally cars the current cars I work on at the moment so I know my way around a turbo but have never worked on these vv turbos so i wouldnt even be able to tell you the difference between them or how the internals work.

 

[Davren]

It's the actuator for the variable vanes in the turbo.

Dave.

 

[adamcot]

Check out:

http://www.holset.co.uk/mainsite/files/2_5_1_5-VGT.php

 

[philomangan]

Thanks for that adamcot Ive got a little bit of a better understanding of whats going on in there now, and after having a look at my 1st post again I should have put the word actuator in after everywhere it says wastegate but it was late so Ive got an excuse. But im still really no further on, air pressure still acts on the actuator so firstly I need to know if its a vacume or pressure. Secondly what it operates at pressure wise. Thirdly what peak boost pressure my car runs then I could do a boost check with a boost gauge and maybe find out that there is nothing wrong at all with the turbo or actuator

 

[Argonought]

Don't pressurise it

All control is done via the VGT (overboost) valve which connects the actuator progressively to either the vacuum reservoir or the atmosphere.

Truly masses of info on this within the Forum.

 

[philomangan]

Dont worry havnt pressurised it was just asking the question if it works on pressure or vacume. So thats the first question sorted any more answers for me

 

[Argonought]

Common problem is leaks/splits within the tubing (either TO or FROM VGT valve).

I had a problem like that and it took me ages to trace it (actually a garage did in the end).

Vacuum gauge should help a lot if that's the problem :chin:

VGT valve could be faulty although mine is still good after 6.5 years

 

[philomangan]

Cheers man will give the hoses a vacume test and see if that nails it.