Not reaching full boost

[Turbolaser4528]

Hey all just got back into the dsm game and got a 92 tsi awd. Problem is the car will hit about 5 psi instead of 10 psi which it was hitting days earlier. The guy who owned it before me said it was probably the wastegate or wastegate actuator that were iffy, but im not sure what to do.

Perhaps it is a boost leak? possible the vacumn lines from the j-pipe? Or maybe my wastegate is the problem? any advice?

It is a stock 14b turbo, stock except for header back exhaust, and suspension. thanks

 

[delta448]

A boost leak test first.
Fix all leaks.
Make sure you have a good vac line from boost source to WG actuator uninterrupted.
Check the turbo for shaft play.
Check for exhaust manifold cracks and pre-turbo exhaust leaks.
Verify correct cam timing.

 

[thebird_19]

Sounds like a big boost leak. I blew my coupler almost off my turbo, and it would only boost to 5psi.

 

[JusMX141]

Sometimes the wastegate flapper arms can "walk" out of the turbine housing on older 14B's, causing the flapper to leave half of the wastegate hole uncovered. This is generally what leads to so much cracking around the wastegate hole on these turbos....a poorly-sealed flapper.

 

[Turbolaser4528]

thanks for your help guys, i'll go ahead and do a boost leak test first and also check the turbo for shaft play.

Another thing, it will hit 5 psi and then around 5k or so rpms itll slowly creep to like 6 or 7 psi.. Weird


Car has 113k on it, stock turbo I'm pretty sure. Ill post back with the results by friday

 

[JusMX141]

Has to be a boost leak or wastegate malfunction....although most of the time if you have a boost leak that's bad enough to cost you a few psi, the car will hit fuel cut.

Here in PA the salty winter roads play havoc on the upper neck of the stock sidemount. Check for pinholes where the upper intercooler hose attaches to the intercooler outlet.

 

[Turbolaser4528]

im really thinking that this is wastegate related. I remember a month ago my brother had a new sidemount put on it because he pressure tested it and thought that was the problem, but still it wasn't boosting.

Another thing is that the car will not hit fuel cut, as im assuming it would if this was a giant boost leak. It'll hit 5 psi and then slowly climb to about 7psi at ~5-6k rpm. It seems like something is not opening or closing all the way, letting boost out.


Any suggestions? I'm 90 percent sure its not a boost leak

 

[delta448]

Definitely sounds like the wastegate is not sealing shut. Take a closer look at the turbine housing, look at the wastegate actuator and arm first, then check the flapper and it's seat. Something is letting exhaust go out the wastegate hole prematurely.

 

[JusMX141]

What you'll be looking for probably cannot be seen without removing the o2 housing.

I'm expecting something like this:

The flapper arm's sleeve has worked it's way out of the housing, causing the flapper to offset the wastegate hole slightly. It's basically a giant boost leak, but on the hot side instead of the cold side of the turbo.

Here's how the flapper should look:

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[Turbolaser4528]

That sounds a lot more like what my problem is. Now, what are the possible solutions? Do i need a new turbo, a new wastegate/wastegate arm, or does it just need a cleaning and readjustment?

 

[JusMX141]

If you're able to catch it enough in advance you can tap the actuator sleeve back into the housing and it will be fine. If the housing gets bad cracks in it from the hot boost leaking past the wastegate flapper (as shown in the first picture I posted) then unfortunately there's not much you can do.

 

[Turbolaser4528]

Allright, well the car has only been driven like 100-200 miles tops like this. Before that the car was boosting fine to 10 psi, so i'm guessing it shouldn't be cracked right?

If I put a couple of washers on the arm thing, won't that help move the flapper back into place? There's a thread boost creep from hell and the guy put a new bushing in and it fixed the problem, let me know if this is can work

 

[JusMX141]

Washers aren't going to do anything....the sleeve itself must be driven further into the housing.

You can see in this photo how far the sleeve itself has worked it's way out of the housing:

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Simply tap the top of the sleeve (where the wastegate arm is spot-welded on) with a hammer and the sleeve should drive back into the housing, allowing your wastegate flapper to cover the entire hole. You should remove your o2 housing first to be sure the flapper covers the hole so you do not drive the sleeve in too far.

 

[Turbolaser4528]

alright, so tap where that green arrow is towards the flapper? I would rather do this without taking the o2 housing off my car since im really tight on time. I can tap it a little and test drive it to gauge how well the flapper is seated. I'm still a little confused where to tap

 

[JusMX141]

The green arrow was simply showing you the sleeve. You need to tap where the RED arrow is in this photo, in the direction of the red arrow, until the bottom of the tapered edge at the top of the sleeve is flush with the turbine housing.

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[Turbolaser4528]

thanks man ill give this a shot in the morning and post back with the results

 

[mnetwork]

What ever happened with this?