Started to occur after o2 housing install.

setup:
2006 Evo 9 with full TBE
Ive tried halman pro with hard spring, i cant get boost over 20psi and it drops to 15psi. Ive tried forged with hard spring, again cant get over 20psi and drops to 15psi.

Is it possible to adjust the stock wastegate? I'm thinking in my installed of o2 housing i might have adjusted something differently.

 

Accure = Occur

When you installed the o2 housing, did you ever remove the WG arm from the WG flapper pin? If so, then you might need to readjust the turnbuckle to create more preload. Yes, it can be adjusted - you disconnect the arm, loosen the nut under the turnbuckle, then turn the turnbuckle clockwise, which threads it DOWN the arm. This will help create preload on the WG arm. When you put the turnbuckle back onto the flapper pin, it should not go on without having to use force to pull the arm up and onto the pin.

 

thank you, i hope that is the answer to my problem

 

It's either the actuator or a big exhaust leak somewhere between the engine block and turbo.

 

You can loose boost with an exhaust leak?

 

you should get a tune too!

 

might be because mitsu says anything over 17psi to the wastegate can damage it.
hallman directions says tubo nipple-mbc-wastegate. here check this out
https://www.evolutionm.net/forums/sh...d.php?t=274733

 

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My wastegate arm is to tight. We were unable to loosen the turnbuckle from the nut.

i think this is still causing my boost to only peak 20psi and fall to 15psi reguardless of what boost controller i have setup.

 

You have to break the backup nut free while the turnbuckle is still mounted onto the flapper valve pivot arm. In fact, this is a preliminary step and should be performed even before removing the cotter pin. It is a b*tch to try and break the backup nut free once you've pried the turnbuckle/actuator rod assembly away from the flapper valve pivot arm. So, best to remount the turnbuckle/actuator rod and start over again. In addition, you can damage the diaphragm by twisting the rod in mid air.

 

Yes, sparky is right. You should loosen the nut before doing anything else. Loosen it and back it all the way down. Then, remove the arm from the flapper pin and tighten the turnbuckle if AND ONLY IF it's not preloaded enough. By that, I mean when the arm is at rest and not on the pin, it should sit slightly below the pin, and you should not be able to get it on the pin without actually pulling the arm up and out of the WG before seating it on the pin at the pin's lowest position.

Lemmonhead, no.

KY, that had to be a joke.

 

An easy way to know if your preload level is too low is to turn your MBC out counterclockwise, all the way to full soft. Then do a WOT run in 4th or 5th. If it's 11-12 PSI then that's at the lowest possible point called base wastegate pressure. Anywhere between 12-14# is pretty low. You should adjust it up to 17-18 PSI on the stock WGA.

 

Well, you don't need to do that. It is supposed to be set where 11-12 is base wastegate pressure. That's how all of us work. Some people adjust it and some people get aftermarket ones, but the system works just fine when using the MBC to add boost over stock. In this case, he's not even at the normal spot, because he can only go up to 15-20psi - that's assuming we're right about it being the WGA.

When I installed my Forge WGA, it wasn't preloaded enough, but my min boost was 18. However, it ramped up very slowly instead of nailing 18-19psi immedately. It would slowly build to 18 and then actually climb to 19-20psi in the mid-range before falling back to 19psi at the top. It gave me a perfectly flat torque curve for several thousand rpm, but it wasn't right. I then tightened to where it still would do 18psi at min setting on my MBC, but once I turned up the MBC, it would nail 26psi immediately and taper down normall from there. I gained 80wtq and hit peak torque much earlier...as you would expect.

 

I agree. I'm just saying that by doing what I suggest he'll know what his current preload level is, and if in fact the WG is preloaded at all, or is instead just operating at base wastegate pressure.

 

You make an important point. Given two mechanically identical turbocharged cars, i.e. identical turbocargers, MBCs and WG's, both limited to the same peak boost level, their power delivery can be totally different depending on how that peak boost is attained and controlled.

The car running the actuator rod at its loosest setting and boost controlled from base WG pressure all the way to peak boost solely via the MBC will have a lot wimpier powerband than the same car with WG preload adjusted higher and the MBC only controlling the final few clicks of boost. Or am I reading you wrong?