Stock SR boost issue

[dragonboy240sx]

Got a S14 SR w/ stock turbo and internals. Had it about a year now. a few months ago I noticed I was no longer pushing the 7lbs of boost I should have been. First it was around 5lbs and now it's more like 4lbs. Had a few issues that I'm in the process of fixing... VTC sprocket went out on me. That has been replaced this week and I'm putting the valve cover back on today or tomorrow. I've been running a KA MAF with a potentiometer as a temporary setup for the past year. I just found an SR MAF that should work for me... hope to get it next week (but this has been on since the install with no problems). So my question is, why would my boost be dropping? Perhaps after I get it all back together with a new VTC it'll be fine... but if not I'll be stumped... could it be a boost leak that is getting worse over time? Anyway any thoughts on the matter would be great... I'll post again when I've got it running again. Thanks!

[PyR0NiAk]

A loose clamp could be getting looser, or a hole could be getting bigger, so yeah, a boost leak could be getting worse over time.

[snake240]

what about the wastegate?

[S13 Curtis]

Its most likely the wastegate check that out first.

[dragonboy240sx]

Thanks guys, I'll take a look.

[dragonboy240sx]

Ok so I finally got my motor back together today with the new VTC sprocket. That seems to be all good now. But I have a very loud noise coming from under the hood (sounds like unmuffled exhaust) and a strong exhaust smell coming from under the hood... so I'm thinking it's an exhaust leak. Could this be my boosting problem as well? And yes I am still able to produce some boost.

[PyR0NiAk]

Yes, it could.. Sounds like it's a manifold based leak.

[CRyan]

Check nuts from exhaust housing to turbo elbow. . .That tends to make super loud noise when its leaking.

[PyR0NiAk]

anything pre-turbo will...

[dragonboy240sx]

Yeah I'm thinking Mani as well. Thanks for the tip about the nuts... I'll check it out.

[dragonboy240sx]

UPDATE: So yes it turned out the gasket between the mani and the turbo was leaking pretty bad. I've replaced it and everything seems to be good now except I'm still only pulling 5psi.

[Sugar]

Make a boost leak tester and check for leaks. Also make sure the car is having no issues getting air into the engine, clogged filter or intake can do this as well.

[PyR0NiAk]

A worn out wastegate will definitely cause low boost. Spring gets soft, it doesn't hold as much pressure.

[dragonboy240sx]

Should I be able to move the wastegate arm with my hands? Cause when I tried to move it... it didn't want to move. I'm going to try to hook it up to a air hose and see if it will move at all this evening. And I'm sure there is nothing blocking air to the engine... If it's not the wastegate I'll be doing a leak check next.

Edit: I was able to move the wastegate arm with a little force... I think I found a used one on here for $20. Going to get that and see if it fixes it.

[PyR0NiAk]

7 psi of force should make it move...

[dragonboy240sx]

Ok, still haven't tested the wastegate... but I built a boost leak tester this weekend and found at least 1 leak. That brought it up to 5psi (it was acutally 4 before not 5) My QOTD is this... when I use the tester it didn't ever actually hold any pressure! However I couldn't hear any more leaks other than the one I found and fixed. Could my wastegate be open a little not allowing me to build pressure or hear the leak? Or was I doing something wrong? As far as I know I had the system sealed up tight. Can it escape through the engine? Thanks!

And I will be checking the wastegate today... I ran outta air before I got to test it this weekend. Got access to a real compressor at work...

UPDATE: So the wastegate opens under pressure just fine. So can anyone answer my question above?

[Sugar]

If it's not holding pressure, you have a leak. Like you said, the engine is not sealed so it is normal to lose pressure. By that I mean 1-2 psi for every like 10 seconds. You should have no issues getting it up to 10psi. My motor's pressure doesn't fall off at all.

It seems like you have a pretty bad leak too, I would imagine it not being very hard to hear.

[dragonboy240sx]

Ok finally got a new wastegate installed this past weekend and it fixed my problem! PyR0NiAk was right all along... thanks!

(it's nice to have 7lbs of boost again... makes a big difference!)

[PyR0NiAk]

PyR0NiAk was right all along... thanks!

Sorry for the late response, but np...