Boost maxing out at 18psi when it should be stock

[THE REAL DEAL]

I've been trying to find out the source of this problem for a few months now. When I first got the car, it would hold boost at 12 psi. A friend and I spent a day doing some of the free mods and when we took out the air filter, we removed the BCS but we put everything back the way it was. Took the car out for a spin and it ended up spiking to like 22 psi. We took it back to the garage and hooked his MBC up in my car to see if we could get it turned down. It kept doing the same thing.

Eventually we decided to port out the turbine housing, o2 housing, wastegate port, and the exhaust manifold to see if that would help. It did help some but it still spiked to about 15 psi in 2nd gear. 3rd and 4th were holding at 12. I left it that way for a couple weeks and now all of a sudden its holding at 18 psi in all gears, getting fuel cut obviously. So last week my friend and I got together again to check if I had boost leaks (because i can't build anymore that 1-2 psi when brake torquing) and to see if we could get the boost down. Well, I have 2 leaks that were obvious. One from those O rings in the TB and another around the SMIC. I'm not sure if the leaks would contribute to this or not. After that, we removed the BCS and hooked a vacuum line straight from the wastegate to the nipple on the intercooler pipe. From what my friend tells me, doing that will keep it at the stock boost setting. It still maxes out at 18 psi. If there's any information I'm missing that may help, let me know. Thanks.

 

[Lordpaxin]

So, you are running NO boost control?

Running the line directly to the wastegate actuator would open at 7psi roughly, the spring rate of the actuator itself.

having No boost into the wastegate actuator would result in wild madcore boost.

is your exhaust completley stock except for porting?

if you removed the BCS, and didnt Put back a MBC or an EBC you have problems.

you need some control

If you have the Intercooler Nipple running Directly to the actuator and are still HITTING 18psi. you must have a faulty actuator, try a friends and see what results you get

 

[THE REAL DEAL]

Well i have a 3 inch downpipe and 3 inch exhaust. The exhaust manifold has some pretty minuscule cracks but most of the dsm guys that i know around town have told me that the cracks aren't bad enough to cause any problems.

The actuator was one of my guesses as well but the arm doesn't seem to stick so i put that conclusion on the back burner. a MBC should be able to keep the boost down right? I'm gonna be making one next weekend. I don't really think that would matter though because the wastegate should be opening at a low psi setting the way i have it hooked up now.

 

[Lordpaxin]

well, you have a creepy setup, sorry.

I had a s16g on a 3 inch 02housing and 3 inch turbo back, and i couldnt get less than 15psi and it would creep to 18psi in no time.

your wastegate just cant compete with that 3 inch. the amount of flow you are getting your small wastegate just cant do enough to help you.

you can either go external wastegate to try to help it, or suck it up and get some fuel mods and turn the boost up for good.

 

[THE REAL DEAL]

it's been a while since i posted this but i figure i'd tell the results since that seems to be a pet peev around here. the arm was practically rust welded to the flapper and wasn't moving so that's why my boost was going out of control. eventually the arm fell off one day and i cleaned up the flapper pin and had a friend of mine put a small bead weld at the end to hold the arm on since i couldnt get the rusted up cotter pin out. this was months ago and since then i've got a new turbo and a motor.

 

[elfroggo]

Haha, the actuator arm fell off. Yeah that would be a problem right there. Inadvertently welded flapper FTL.

 

[Lordpaxin]

Knew it was somethiing with that actuator, ....

sometimes its nice to see old threads come back and give an update.