Ok I have a S5 hybrid on my S4 motor. I have been searching on this subject and haven ot really found the answer. I read the S5 has some sort of electrical boost control or somthing and that the actuator needs less pressure to operate. So I was wondering since I have a S4 if I should swap the actuators? I am having a hard time building boost. Somtimes I can spool up great other times I cant get 8 psi. So I was wondering if the S5 actuator could be the problem...? Boost leaks have been gone over and etc... Like I said 1/2 the time I can spool the other 1/2 I cannot.

 

bump

 

The question becomes why does it work sometimes?

After next week I'll be experimenting with my S5 J-spec.
I suspect a wastegate issue.

I plan to Tee a boost gauge directly into the waste gate hose.
Except during blow-off, it should almost always be lower than the UIM pressure.

 

I'm a little late posting in this thread.. but I figure this may help others in the future who have spool or low boost issues..

When porting the S5 wastegate, the lever has to be pried and bent a little to clear the lip on the housing so it can be pushed forward enough to open the flapper door all the way to port the holes.. once the porting is done, you would simply bend the lever back into place..
Depending on how the lever was bent, it is entirely possible to bend or distort the entire shaft the flapper is on.. When the shaft is bent a certain way, pulling the lever back all the way closed, can actually cause the flapper door to re-open a bit....
the actuator arm connects to the lever and puts some pressure on it pulling it back to keep the wastegate closed.. however, it's entirely possible that if the shaft is bent, the actuator arm pressure could be pulling the arm back enough to have the shaft ride up on where it's bent and cause the wastegate flapper to open up or not seal.. you may "think" that the wastegate is shut, because the lever is all the way back, but it isn't...

the easiest way to check for this is to pull the downpipe off and remove the backplate (2 bolts) .. the flappers should not jiggle and they should seal correctly.. it shoudl be fairlyh obvious if the flapper does not seal correctly..

I've actually had this situation happen on my own hybrid setup... I could only make 12 psi boost.. even when I had my boost controller maxed out... spent numerous days checking for boost leaks etc.. finally pulled the turbo and found the situation described above.. I was able to remedy the situation using a screwdriver and hammer, so that the wastegate held shut no matter how much force was used to pull back the lever.. it no longer rode up on the bend in the shaft.. life was good again...

anyhow.. just something to watch for..