Technical Wastegate / overboost valve......jtd

[roy lovelock]

Hiya
ive been searching though and found loads on this but cant find specifics on the fault ive got (i could be blind).
probs so far and fixed-
right so far ive had egr valve replaced, then i had intercooler pipe split, all has been good since (well for 1 week that is).
oh yeah a break caliper.


new problem just need some professional insight to-
anyways new problem just arisen, i now rev the car to 2200 and i here a pssst noise (not the same as the whoosh noise on the intercooler pipe - this is more like a valve opening).
Im suspected the wastegate is opening for some reason, am i correct in thinking this is most likely down to the maf sensor? or do these valves fail. in not sure if they are pressure operated or electomagnets that open it, but if its the later then the valve is fine and its most likely the maf.

the car still pulls like a train and gets 53mpg, no smoke etc (yet), but when in the turbo range it does feel a bit lumpy with the power delivery but below the turbo its running fine.
thanks for your help, if it is the maf i will get a new one tomorrow i just need your views and experiance on the diesels as mine is still pretty new.
thanks again
roy

 

[Davren]

The Stilo JTD does not have a wastegate, it has a variable vane turbo. The adjustable vanes are controlled by a vacuum operated actuator mounted on the turbo.

The actuator is controlled by a boost valve that was originaly located below the air filter. There was a modification that relocated the valve higher (to the side of the battery box) to prevent water ingress into the valve and its connector.

Your "pssst" noise is likely be a leak in one or both of the small diameter plastic vacuum pipes that go to the valve.

If you use the search button on the red bar at the top of the page and search for "Turbo Boost Valve", you'll find numerous posts on this subject.

 

[john55]

Lumpy power delivery is often a sticking EGR valve

 

[roy lovelock]

Lumpy power delivery is often a sticking EGR valve

?? brand new egr on there and that is 100% fine.
anyways ive found the problem, under the n/s light there was a valve of some sort with a wire and a couple of tiny vacum pipes. i traced thes pipes though and found that the one going to the turbo (sorry dont know the name of these parts) had a nick in it where it had been rubbing against the filter box over the years. i taped it up as a get by then put a load of looming scotch tape (self welding type) on the pipe, infact its probo better protected now, the hiss has vanished and the power is back, the car has got its mojo back lol.
cheers
roy

 

[Argonought]

The actuator is controlled by a boost valve that was originaly located below the air filter. There was a modification that relocated the valve higher (to the side of the battery box) to prevent water ingress into the valve and its connector.

Your "pssst" noise is likely be a leak in one or both of the small diameter plastic vacuum pipes that go to the valve.

anyways ive found the problem, under the n/s light there was a valve of some sort with a wire and a couple of tiny vacum pipes. i traced thes pipes though and found that the one going to the turbo (sorry dont know the name of these parts) had a nick in it where it had been rubbing against the filter box over the years. i taped it up as a get by then put a load of looming scotch tape (self welding type) on the pipe, infact its probo better protected now, the hiss has vanished and the power is back, the car has got its mojo back lol.

Sounds like someone's diagnosis was spot on then

Don't forget about moving it though

 

[roy lovelock]

yep thanks guys, moving it?, mine seems pretty clean and dry, i have the under shield in place so that could be the difference i suppose.
i will have to go about doing that in the summer - no time atm, im even paying someone to do the cam belt which is unusual for me lol.
roy

 

[roy lovelock]

oh well its came back last night, i suppose there is another hole in those vacuum pipes, does anyone know the bore diameter on the pipe?, i havnt got time to remove it measure it then order - i have two year old twins to look after all day. so if anyone knows the size it would be a great help - im gona replace the lot with silicon vacuum pipe now.
thanks
roy