HSV XU6 blower loosing boost.. HELP!!

[-sbxu6-]

hey guys i own a super charged hsv xu6... its been very loyal to me till i moved to qld from vic and i seem to be having problems for some reason i cant pull full 10 psi boost, its topping at 3 - 4, unless its colled then all good, got a new belt, new bearings, the shafts are clutch less so cant be that, if it was the blades on the charger it would change it would just be set on the boost how ever low...

now i was told it may be a waste gate problem??? they are gonna put it on the dyno to have a little look, then if thats the problem try and sting me 500 to fix it... now im very mechanicly minded, well fairly but never dugg this deep into a charger, so if thats the problem how can i find the waste gate my self and clean it, he thinks it may be sticking, web sites or images or steps would be great fellas... thanks heaps

[HARVZ-6]

the "waste gate" hes refering to is the boost control valve.. on the passenger side of the charger theres a little black cylinder with some vaccum lines coming off of it.. on the bottom is a little shaft connected to a pivot on the charger.. make sure thats moving freely

but that shouldn drop the boost.. id be checking for gasket leakage

an you said unless its colled? do you mean when its cold it hits full boost?

[chargedvx6]

Has any work being done on the car recently? It's unusual for a super 6 to loose boost just out of the blue. I'd definately be observing the boost bypass actuator on the charger next to the throttle body. With the car idling give the engine a few short sharp revs from the throttle cable arm and the boost bypass actuator should force it's arm all the way down onto the stop screw. Also check all the vacuum hoses in the vicinity, it's now out of the question for one to leak air. Just replace em with generic vacuum hose if needed

[don0xer]

boost control solenoid could be the prob... its located on the back side of the motor under the U bend/throttle body, its a black box with 2 vacc lines coming off it... you can actually disconnect it and join the 2 vacc lines together iirc... might save you some dosh

[Tsunamix]

At high temps, everything expands a little. So if something is expanding and your getting a pressure loss, I'd be looking at places where 2 different materials join or seal.

Copper expands more than steel, so ant place there is a copper gasket would be worth looking at. The other thing is right on the end of the blower snout. Rubber belts grow a little at temperature, maybe your simply getting belt slip. Check belt tension - You should be able to push it to the side by no more than a fingers width at cold. At hot, no more than 1.5 fingers width. If you can, tension it up. Another trick is to grab a piece of chalk and scribble over the ridges on the blower pulley. Chalk dust is quite abrasive, but soft. It will act as a gripping agent. If after a while you can still see the chalk marks, your belt is way too loose.

There the obvious things. I don't know how the blower seals are constructed on the L76 but they could be conceivably bleeding compressed air at temperature. Unlikely though.

[-sbxu6-]

thanks guys, i will have a little look, see what i can see, no major work has been done other then new diff, it was hard to tell wen it started exactly, as i was living over seas for a little while. has 10 pound pulley but other then that nothing huge, i put a brand new pulley on yesty, and it only hit 3 at first but once it was warm it hit 10, so was wierd, then i turned it back of and back to 3 again... and yes when its cold it always hits 10, he thinks this part that may be sticking once warm any build up may be melting and causing the sticking problem, then wen cold its hard and no longer does it.... any more help im gonna try the first few ideas

[-sbxu6-]

ok latest updates, i pulled the cover off and found the black box thing, but that seems to come all the way out, well most of the time, it doesnt seem to come fully out ever time i hit the throttle, but may just come half way, but i went for a drive to get it warm, pulled over had a look and same kind of thing, its not like it just comes out a little, so i played with a few lines gave it a few revs, and continued driving then i was hitting 7 - 8 pound, but after a bit back to 3, so im think maybe one of the lines that runs from the TB to the boost value then into the charger, if thats how it works..??? what do use think???

[-sbxu6-]

PROBLEM NOT SOLVED, THOUGHT IT WAS, WENT GOOD FOR A WILE BUT IS BACK

i replaced the hose that runs from the plenium to the boost thing, which fixed it for a wile, but problem is back, i think it is a hode problem, but dont no were to get new ones from or which ones could cause this kind of problem

[chargedvx6]

Have you observed the bypass actuator on the side of the charger when you rev it? If the arm doesn't move all the way down to the stopper when you rev it that will be you prob. It is help on by 2 x 10mm bolts which allow for adjustment. Moving the actuator down will make it shut better if it isn't already.

What size pulley are you running BTW?

[-sbxu6-]

yeah it seems to run most of the way not always fully, running 10 psi boost mate, it seems to always change boost now, im replacing lines now try and get rid of any other air leaks

[chargedvx6]

What size is the outside of the belt surface on the pulley in mm?

[-sbxu6-]

i have no idea on the size, i just run of a boost gauge, i new the size but forgotten now

i have adjusted the boost thing down lower but still hasnt fixed the problem, but i have noticed that its taking longer to loose boost from going from cold to warm and the only thing i have done that would cause that is i have taken the charger cover off, so i figure its staying cool abit longer, so what ever the problem is must be under the cover and clearly heat is making the problem, now just got to figure out the problem, any other ideas..

thanks

[-sbxu6-]

has anyone got any more ideas i can try. please

[HARVZ-6]

and its definatly not blowing past a gasket as everything expands?

not making any strange noises when the boost is lost..

not miss firing?

[redcv6]

sounds simple, but have you checked the plugs?

[-sbxu6-]

havent checked the plugs, cant see that being the problem as its not at all when not boosting, i cant notice a gasket leaking air, but i guess its possible, but i cant notice any odd noise's

[HARVZ-6]

so its just losing the boost, not missing or carrying on?

[blueV8vl]

are u sure it could be the gauge playing up ive had one gauge reading 8psi tied another brand runs 11psi.

[-sbxu6-]

not missing at all, runs like a kittne other then boost lost, not the gauge either, i can feel the difference, it is noticeable. so clearly not the gauge, thought of that already but yeah not that

[oztech007]

Another thing to check is the Supercharger Bolts to the Inlet. The bolts can loosen over time and could cause compression loss. I checked mine about 6 Months ago and they were quite loose. Tightened then (not too tight). Just so the bolt grips down and a little more.
Worth a try.
And while your at it, tighten the Inlet Manifold Bolts as well.

[-sbxu6-]

thanks mate, it clearly has something to do with heat, it will be at standard running temp, and on a hot day plays up, but on a cool night be all sweet, i was driving for about an hour or 2 tonight up in north qld and all sweet, whole time boosted sweet, left a clubby for dead while i was at it, so just trying to work out on the engine what can be affected by heat to do this... the engine was hot but was sucking cold air, so it was just cold enough to be fine. if i hit it too hard to too long tonight it played up a little but bugger all

[barnieboo]

hey guys, i have a vtII hsv xu6, it has modified exhaust, cold airbox k&n and all the normal shit done. my problem is it bogs down when i stomp on the loud pedal. if i put my foot into it gradually its mint, but if i jump on it, it bogs down, almost like cutting down a couple of cylinders, it doesnt miss at all normally, sometimes on the highway when i put my foot down to slowly pass it bogs down also. it definately sound electrical, TPS,? mass airflow metre?

[drift-it]

^^^^ when was the last time u replaced plugs and leads??? had the same problem in my n/a VT v6. didnt miss until overtaking or stomping it. problem was leads arcing out through each other.