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Discussion Starter #1
Hey guys, just finished installing my headers, uppipe, downpipe, and cat back. I flashed the ecu with the stage 2 from the cobb accessport. Supposedly its supppsed to be at 17.5lbs of boost, but im only able to hit 16lbs max.

My downpipe is the perrin one piece with the seperate waste gate pipe. It has a metal divider that goes into the turbo. Could this be the cause? I was skeptical about the metal divider because ive heard it can cause problems with the wastegate opening or closing.

Is there a way to check if the wastegate is performimg correctly? From what i understand it wont operate unless under load right?
 

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The Fruit
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year? other mods? .. you mention running a header.. is this el or uel? .. also if the diameter of the header is larger than the stock manifold then you may have to run a map with a lower wastegate duty cycle. Reason being the maps were designed to be run on a car with a factory manifold. Headers will slightly drop spool time. The divider shouldn't be a problem. If it was hampering the wastegate from opening you'd have too much boost, not too little.
 

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Master Baiter
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You're running a map that's not designed for the modifications you have, and you wonder why it's not working properly?
 

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Nimrod said:
Its 06 STI, no other mods except an intake. It has uel headers.
Which intake?

The map notes clearly outline what modifications are supported.
 

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how do you know what boost you are hitting? The AP or a boost gauge? If you have a gauge, does it correlate to what the AP reads?
 

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Discussion Starter #9
One thing i also noticed that may be unrelated is that when i shift above 3k+ rpm it makes a bov sound, like air being purged. What could cause that?
 

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possible boost leak. you should be hitting peak boost right around 3K and holding until it tapers at around 6K.

I am not sure why you installed an up-pipe on that car, but since you did - that means you were definitetly touching a lot of parts and could have loosened a connection.

I couldn't hear the noise you are describing when this happened to me, but I found I had a tear on the turbo inlet hose which prevented me from getting to target boost. Since you put the up-pipe on, you had to remove the turbo; I would highly suspect you may have torn it. If you look at the thing funny, it tears.

Other places that get people:

- Not putting the BPV back on tight enough, or when they do, they allow the boost gauge "T" fitting to loosen - which will result in lost boost.
- Not getting the turbo-to-intercooler hose on correctly. You have to feel around where you can't see to make sure it is on.
- Using the original turbo-to-downpipe gasket instead of putting on a new one.
 

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Discussion Starter #11
I didnt take the turbo or intercooler off when changing the uppipe, or anything for that matter. I did go and tighten up the bolts to the upipe from the header and im getting 19lbs of boost from 3k rpm, just like you said. Perhaps it was a leak?

Im still getting that bov sound when i push the clutch in while umder boost. I can also hear the turbo spool up, its much louder now. Almost sounds like a diesel, maybe not as loud. I do have the heat shield off on the turbo until the new one arrives, maybe thats why it sounds louder.
 

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Discussion Starter #12
Btw should i be concerned about that much boost? The car is running awesome with the exception of that bov spund.
 

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how did you change the up-pipe without taking the turbo & intercooler off? What you call the up-pipe is the pipe connecting the exhaust manifold to the turbo, right? The turbo is mounted on top of the up-pipe, while the downpipe is mounted to the back side of the turbo. The turbo inlet is the large rubbery hose connecting to the front of the turbo.

19lbs of boost doesn't sound that high if it is a quick peak number - especially if you are in cold temps and at sea level.
 

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Discussion Starter #14
Yes, the uppipe connects the headers to the turbo. I think the turbo is also mounted somwhere on the engine, I removed both the original downpipe and up-pipe and it was still on there pretty solid. Not sure what else to say. Maybe it's different on the STI than a WRX?
 

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possible boost leak. you should be hitting peak boost right around 3K and holding until it tapers at around 6K.

I am not sure why you installed an up-pipe on that car, but since you did - that means you were definitetly touching a lot of parts and could have loosened a connection.

I couldn't hear the noise you are describing when this happened to me, but I found I had a tear on the turbo inlet hose which prevented me from getting to target boost. Since you put the up-pipe on, you had to remove the turbo; I would highly suspect you may have torn it. If you look at the thing funny, it tears.

Other places that get people:

- Not putting the BPV back on tight enough, or when they do, they allow the boost gauge "T" fitting to loosen - which will result in lost boost.
- Not getting the turbo-to-intercooler hose on correctly. You have to feel around where you can't see to make sure it is on.
- Using the original turbo-to-downpipe gasket instead of putting on a new one.
WHAT? You do not need to remove a turbo to change an up-pipe.
 

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Discussion Starter #18
The OEM BPV was much quieter before, I didn't even hear it until changing all the exhaust.
 

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Discussion Starter #19
Oh no, didn't tighten the wastegate arm at all. Didn't know that was required. Could you explain why Torque? I'm pretty happy with the boost atm, seems to be running good. Though watching the AF/R on the accessport it may be running a bit lean, nothing to scary though. I'm going to take it to a dyno shop that specializes in Subarus in the next few days and get it dyno tuned.
 

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Nimrod said:
Though watching the AF/R on the accessport it may be running a bit lean, nothing to scary though.
The AP AFR value uses the OE front O2 sensor, which isn't accurate under WOT conditions.
 
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