Part Throttle full boost and full boost with n75 unplugged

[ceS3r]

The last week, the hose that goes from the N75 to the Charge pipe decided to split apart, so Part Throttle would send the boost to 10 psi and then let go by itself, so, I decided to unplug the N75 so that the car would run on actuator pressure (don't know if this is the right term). Everything fine, running at 9 to 10 psi at full boost. Yesterday I "fixed" the hose, since this country is Sh#t and you can't find anything to replace it with (venezuela) and it seemed ok, boosted ok at 15psi, part throttle ok until today.... Today the car starting doing the same as before.. I checked the hose, didn't see anything obvious so I proceeded to disconnect the N75 until I figure how to fix it... But what a surprise, the car was still runing the same and now it OVERBOOSTS with the n75 unplugged, yes 18 psi with the n75 unplugged and horrible part throttle at 10 psi. The question is, what now? Is the N75 ********? Broken WG and/or Actuator?? Please this is driving me nuts.

Car is an Audi S3 8L BAM 225hp, no mods only cone filter and forge tip

 

[JUS3IN]

iirc you now need to try running the charge feed straight to the actuator and see if its still overboosting... should run at about 6psi I think? that will eliminate the n75, if its still overboosting it must be actuator or turbo/waste gate issue.

 

[JUS3IN]

you can check the actuator by attaching a tyre valve (cut the flappy bit off) into a hose to the actuator and pumping to 30 psi and see if it holds pressure.

 

[ceS3r]

you can check the actuator by attaching a tyre valve (cut the flappy bit off) into a hose to the actuator and pumping to 30 psi and see if it holds pressure.

Thank you for the response. I will try that and post tge results. I've also read that you can try to move the actuator by hand?

 

[ceS3r]

So, I fitted my old N75 just to test it and it remembered me why I replaced it.... 21 psi boost, so, unplugged again and running at 18psi........ I've also managed, just out of curiosity, to move the wastegate by hand, it required strength, not excesive tho.. So, my question is, is the wastegate supposed to be opened just by hand? I'm looking forward tomorrow to connect the Wastegate line directly to the Charge Pipe and see what happens. In case that I'm still overboosting while the wg is directly connected to the charge pipe. does this means that the actuator and/or wg is cracked? If that's the case, can I just buy an universal WG? I'd really appreciate if someone could answer all of my questions!

 

[JUS3IN]

The actuator can be moved by hand yes, its tough but can move with some force. You may have a problem with the wastegate penny sticking or the turbo. After market wastegates wont work, easiest fix would be a new/used ko4. Check for codes and your pipework again first. If the diaphragm inside the actuator is split or damaged you can overboost. A cracked hotside/wastegate would usually cause a lack of boost unless the crack is somehow inhibiting the wastegate penny moving away from the hole.

 

[ceS3r]

The actuator can be moved by hand yes, its tough but can move with some force. You may have a problem with the wastegate penny sticking or the turbo. After market wastegates wont work, easiest fix would be a new/used ko4. Check for codes and your pipework again first. If the diaphragm inside the actuator is split or damaged you can overboost. A cracked hotside/wastegate would usually cause a lack of boost unless the crack is somehow inhibiting the wastegate penny moving away from the hole.

Well I'll test today the actuator straight to the charge pipe and post results.. Hoping it's nothing too serious.

 

[ceS3r]

Hi everyone, just wanted to give a quick update. So, I bought some hose to fix my previous "fix" of the hose coming from the N75 to the charge pipe. What I did was I cutted the broken part of the hose and attached a T piece to it and then another hose to the charge pipe.. The thing is that the T piece collapsed (pic attached).. So, I just replace it with a new hose from the n75 to the charge pipe and voila, problem gone!

My question is, now that my problem is solved, I still have the curiosity why if the line that goes from the n75 to the charge pipe collapses or get blocked, the Wastegate behaves like that? Thank you all for your respones

 

[badger5]

wastegate not seeing pressure it does'nt open so boost control is lost