need help no boost on my gti

[MikyHRC]

Hi guys, I need a help, I bought 2006 polo gti and it runs Giac KO4 tune with 380 infectors on a 3 bar FPR. I drove it for couple of weeks and everything was ok until I took it for a dyno run last weekend and it only made 100kw at wheels. I drove it back home and I didn't have any boost. I have checked the hoses from IC and turbo and I couldn't find any boost leak, unfortunately I don't have the boost gauge yet to see what boost I'm running

I read somewhere that it could be faulty N75 boost valve. Pls let me know if anyone of you had the same problem I'm kind of stuck and not sure what to check for, I don't want to take it to stealership. Any help appreciated..cheers Mick

[HAR80N]

check the vac lines and the DV i got a audi s3 the other week and went like a nugget and was a split hose that went to the dv fixed that and went awesome with the hose split was just pushing open the dv and dumping all the boost

[seangti]

You can easily check if it's the N75 by disconnecting it and going for a drive. If it feels the same, than that could be the culprit. If the boost leak is of reasonable size, your car could run rough (not always though), and/or you can hear it. I've blown an IC pipe the L shaped one straight off the turbo, huge blow out yet could still drive the car down the highway off boost to get home. With N75 disconnected, it'll boost between 6-8psi, which still feels like no boost. I had a N75 go on my car, but it was intermittent for a while before it was dead. Scanning it will also show a fault if you can get access to a scan tool.

There's nothing wring driving around with the N75 disconnected, just low boost.

My guess is that t's more likely to be a boost leak from the dyno run. Check all hose clamps, pipes are aligned/square, vacuum lines are right. Some cracks/holes can be small, but add boost they expand.

[MikyHRC]

check the vac lines and the DV i got a audi s3 the other week and went like a nugget and was a split hose that went to the dv fixed that and went awesome with the hose split was just pushing open the dv and dumping all the boost

Thanks HAR8ON, I will check the vac lines and the DV today.

[h100vw]

Thanks HAR8ON, I will check the vac lines and the DV today.

So does it have a boost gauge? Because it seems like there's two stories here. I don't see it putting down 100kw making no boost whatsoever.

Gavin

[Bora Sport]

Could it be the old broken wire to the N75 trick. When mine went on the Polo it would boost sometimes and then not. The wire must have been touching occasionally. Eventually of course it felt like it wouldn't boost at all. Soldered the wire back together and the smile returns.

[MikyHRC]

Hi guys I think I found the problem, I've got the hose coming of N75 going down to wastegate actuator a its snaped off right where its connected to WG act. That could be it right? Now the thing is the hose is actually thicker with bigger hole on N75 end and thinner with smaller hole on WG end if I am correct (or I'm looking at the wrong hose?) I don't think the original hose that's in is going to be long enough to reconnect it though. Am I going to be able to get a similar one from Supercheap or Repco? The spare one I have its same size all the way through, is that gonna be a problem if I put this one instead?

[h100vw]

Hi guys I think I found the problem, I've got the hose coming of N75 going down to wastegate actuator a its snaped off right where its connected to WG act. That could be it right? Now the thing is the hose is actually thicker with bigger hole on N75 end and thinner with smaller hole on WG end if I am correct (or I'm looking at the wrong hose?) I don't think the original hose that's in is going to be long enough to reconnect it though. Am I going to be able to get a similar one from Supercheap or Repco? The spare one I have its same size all the way through, is that gonna be a problem if I put this one instead?

If there's no connection to the inlet manifold, the spring is holding WG closed. I have never seen that run on the street. I can imagine that eventually the exhaust would blow the WG open. Not sure what boost you would see.

Don't worry too much about the diameter of the pipe.

Is there enough to take the broken bit off the WG and shove it back on?

[MikyHRC]

No, the original one doesn't seem to be long enough anymore, I'm gonna try to pull the original one out and run it around the other way to make it reach,if its not long enough I just got some pipe from Repco with similar diameter so I'll put that one in and try to make it fit. Hopefully the different diameter is not gonna be an issue��

[sambb]

Yeah the hose that heads down to the wastegate actuator is thick and then tapers where it goes onto the actuator nipple. Mine tore there too. I'm not sure how that's giving you less power though - should be tearing your head off! Or maybe that's the prob, it did for a bit and now its in a limp mode due to the overboosting? not sure
That pipe runs up through a heat resistant sleeve with another hose that goes into the bottom of the turbo inlet pipe. You will be able to pull some extra length through but where you cut off the hose to get a clean end will now be too big a diameter. Just clamp the hell out of it for now and you can just buy some silicon vacuum hose from repco etc. Has to be silicon though so that it has some longevity. Use the existing turd wastegate hose as a pull through to get the new hose down through the heat resistant sheath.
Maybe with that sorted and clear codes you may get your boost back.