mkiv golf gti 1.8t only hitting 3psi boost

[tashaw]

Hi all,

I just recently purchased my first turbo car, a 1999 Golf Gti mkiv 1.8T
so according to the previous owner, he told me that the previous owner before him had the boost put down to 3psi (apparently his wife was driving it) so boost is currently only running a sad 3 psi.
After looking around I dont see anything installed to adjust the boost so my question is how do I turn the boost back up to stock? Also what exactly is stock boost supposed to be lol? I am pretty dead certain that I do not have a boost leak... any suggestions would be hugely appreciated

Cheers guys and merry christmas!
Tasha

[Jharra]

The ecu will make it run in safe mode


Sent from my iPhone using Tapatalk

[tashaw]

By safe mode I assume its the same as limp mode? She has no trouble accelerating or anything, she hits the high rev ranges no problem without losing power and it hits 3psi and holds.. it just doesnt go over 3psi lol. Sorry if we arent on the same page here

[h100vw]

Not limp mode, sounds like maybe the actuator has been backed off. So I'd be disconnecting the N75 and seeing what boost it makes. Then tighten the actuator until it makes 6-7 PSI and leave it there.

Gavin

[tashaw]

Hello again Gavin! I thought I'd post on this forum to see what others might have to say ok so if I disconnect the n75 valve what should I be looking for if I need to tighten the actuator? Should it be boosting higher then it currently is? Thanks

[h100vw]

Hello again Gavin! I thought I'd post on this forum to see what others might have to say ok so if I disconnect the n75 valve what should I be looking for if I need to tighten the actuator? Should it be boosting higher then it currently is? Thanks

With the N75 disconnected, it will be open and boost will go straight to the actuator. It will open the wastegate at some point and stop the turbo making any more boost.

On the end of the actuator are a couple of nuts and possibly a clip to stop them coming undone. Remove the clip if there, then wind the rear nut down away from the end of the rod a couple of turns and follow up with the other nut and refit the clip. This is effectively shortening the rod.

The preload on the actuator will be higher and require more boost to open the wastegate. You'll see this on the boost gauge.

Don't go mad cranking it up. A couple of turns will be plenty.

Once you have 6-7 PSI, reconnect the N75

Gavin