More problems holding boost

[Splinter]

So Ive got the FCD in (mostly because I was hitting cut at 11-12psi) and Im trying to run 14 PSI

At WOT, it'll give me MAX 10.5, unless Im going uphill or have JUST switched gears

At part throttle, and for a second after I change gears, I can make 14, 14.5.

Shitty stock BOV? Weak MBC spring? Internal wastegate?

idk

[555BCTurbo]

Small ass factory turbo...


Do you have your factory boost controller disconnected?

[dzx]

Do you have your factory boost controller disconnected?

That would be my guess as well. If you unhook it from there and put in a manual boost controller you should be fine, I wouldn't personally run past 13psi though.

[vrg3]

If you suspect the blowoff valve, just cap it off and go for a ride (being very careful to close the throttle very gently and gradually every time).

What kind of MBC are you using?

What's your exhaust like?

[Splinter]

Small ass factory turbo...


Do you have your factory boost controller disconnected?

...

How would I run 14psi with the factory boost controller?

yes Im running an MBC.

[Splinter]

What kind of MBC are you using?

What's your exhaust like?

MBC is the homedepot special with a 1/16th bleeder hole in the body

Exaust is factory with no muffler.

[vrg3]

Well, one kind of abusive way to check your MBC would be to simply disconnect it and see if you can sustain 14 psi with nothing pressing on the wastegate actuator. Of course, if your foot slips while doing this, you could damage your engine.

But if we assume that the MBC is good, then I suspect a restriction in the intake or exhaust. If one or both of your catalytic converters were clogged, or if your air filter were really gummed up, I think you might see these symptoms.

If you haven't replaced the air filter recently, I say just buy a cheap brand-name filter and replace it.

The cats are a little more tricky. You can undo the downpipe-midpipe joint and go for a drive "open downpipe" to test the second cat. The first cat is built into the downpipe, though, so you'd need another downpipe to swap in to test that, since you don't want exhaust coming straight out of your turbo.

[dzx]

My 16G's wastegate used to open at around 14-16psi in the lower gears with the wastegate line off. I suspect the exhuast gases were forcing it open. Since I went to an external wastegate, i've been able to hit over 20psi in first gear.

[BAC5.2]

My 16g definately doesn't open at 16psi with the line off. EVO's dont either, lol. We had one guy come in saying "I let off when it hit 32psi".

External wastegate is the best way to control a turbo (if it's properly setup).