Boost leak where to next?

[newsh]

Bypass valve = DV = Diverter Valve = Dump valve, they are all basically different names for the same thing..

[dennis1987]

i managed to change the dump valve and the WGFV today, the WGFV was completely knackered, i will try and get a picture later and although the dump valve seemed to be in good order i changed it for a known good one of the s2 i have the same as the WGFV, the car seems to hold boost better know there is still a boost leak but the boost pressure doesnt seem to fluctuate like it used to it goes up to 2.3 bar and then syays indicating that, but i can still feel a hesitancy which im assuming is just an ordinary bost leak, i also changed the small hoses that go to the top of the dump valve and the inlet manifold as these just looked tired and brittle, im going to try and change the michelin man pipe at some point aswell just as a matter of course and it also seems to be the cause of alot of s4 boost leak problems even when it seems okay

[dennis1987]

heres a few piccys of the WGFV, and one of the clips holding the hoses on, one of them was so rusted it just snapped in half, and the valve itself must have been quite fragile or already broken because it just came apart in my hand (as can be seen by the snapped t-piece section

[dennis1987]

quick update on this, i have had more of a look at the pipes, and i have replaced a few of the small vacuum hoses that were perished and beyond doing any good, i also made sure that all the clips were done up good and tight i had another look at the michelin man pipe and that is in perfect condition to rips or anything on that, the maf to turbo pipe is good but the problem i have now encountered is that the car does not boost above 1.0 bar (indicated on computer) no matter what i do, it perked up just after my tinkering yesterday for a couple of miles then after i gave the full beans it just sort of gave up, im running out of ideas, i think im going to just buy a new WGFV for good measure and get the uprated s3 dump valve, but any more ideas anyone?

[AndyP]

1 bar on a UrS4 digital display would indicate that it's not boosting at all now. Are you sure you've connected all the vac hoses back up correctly? Also try pulling the ECU fuses for a few mins to reset any errors that may be stored in there.

[dennis1987]

1 bar on a UrS4 digital display would indicate that it's not boosting at all now. Are you sure you've connected all the vac hoses back up correctly? Also try pulling the ECU fuses for a few mins to reset any errors that may be stored in there.

pretty sure all of the hoses are connected correctly and are all connected, I had the battery disconnected while i did the work so the ecu faults should be cleared, as i have said im stumped really, i made sure that the WGFV was connected properly and so to with the dump valve

[AndyP]

Have you tried pulling the error codes?

[dennis1987]

not yet i dont know how to without vagcom,

[merlin's S4]

Have you blown off one of the vacuum lines to the moisture trap located on the bulkhead at the back of the engine bay? Or even the vacuum line into the ecu itself? Do you get overboost protection at all (ecu cuts fuel acting like a big missfire)?

Seems strange to only read 1bar. Even with no boost control you should see 1.4-1.6 bar on the gauge from mechanical boost.

[dennis1987]

Have you blown off one of the vacuum lines to the moisture trap located on the bulkhead at the back of the engine bay? Or even the vacuum line into the ecu itself? Do you get overboost protection at all (ecu cuts fuel acting like a big missfire)?

Seems strange to only read 1bar. Even with no boost control you should see 1.4-1.6 bar on the gauge from mechanical boost.

hello gents just been out to check the lines again with a torch and it seems you are right i had blown one of the hoses of the fuel vap canister, stuck it back on went for a quick spin gave it WOT went like stink for a couple of seconds then went back to nothing, pulled over and sure enought the little ****** had blown off again, probably didint see it in my annoyance earlier so popped it back on and hey presto full boost is restored, when the pipe was off and the engine running it was i think sucking air in, which probably explained the rubbish fuel economy

now i have a question, the pipes around there seem to have the ends crimped on can i replace it with new pipes with t-unions and clips or does it have to be the same as what is now on there or else im going to carry on blowing the ****** halfway across the engine bay whenever i hoof it

cheers lads
dean

[dennis1987]

what a pain in the **** S cars are

[merlin's S4]

Yes replacing with a t piece and new hose is fine. I have done this using heavy duty silicone hose from Roose Motorsport.

[dennis1987]

Yes replacing with a t piece and new hose is fine. I have done this using heavy duty silicone hose from Roose Motorsport.

cheers mate i will do this when i get the t-pieces asap cant cope without the boost, it isnt very good without any boost at all

[dennis1987]

right then i have changed all of the vacuum lines to silicone hose and the car now goes like stink, my only problem now (yes there is just one more) the car holds boost all the way up the rev range but after i change gear the boost drops and the car sort of struggles to accelerate for a couple of seconds literely 2-3 seonds then the boost picks up and the car feels nomal again, it only does this after WOT is applied after a gear change, could one of the pipes be collapsing and just needs that small respite from the boost to spring back into shape again?

cheers for all your help guys were almost there one last push for te newbie and we are there i think

[prj]

right then i have changed all of the vacuum lines to silicone hose and the car now goes like stink, my only problem now (yes there is just one more) the car holds boost all the way up the rev range but after i change gear the boost drops and the car sort of struggles to accelerate for a couple of seconds literely 2-3 seonds then the boost picks up and the car feels nomal again, it only does this after WOT is applied after a gear change, could one of the pipes be collapsing and just needs that small respite from the boost to spring back into shape again?

cheers for all your help guys were almost there one last push for te newbie and we are there i think

Are you running a BOV?