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Old 02-18-2013, 03:13 PM   #76
mike-tracy
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Merko, a friend of mine has a 91 Legacy SS with an ej20g swap was running into problems like yours. What fixed the problem for him was switching to NGK V-Power Copper spark plugs, and gapping them down to .31" from the stock .38-.40" gap.

I suspect the smaller gap made the biggest difference, but I have noticed the older Subie engines run a little better on the NGK coppers than platinum or iridium. Possibly due to copper's superior conducting properties?

Now he's enjoying 18+ psi on his td05-18g and robtune.
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Old 02-19-2013, 11:25 AM   #77
jaymmmbee
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Quote:
Originally Posted by Merko View Post
Yes please do!

Unfortunately mine is still stuffed, haven't had the willpower to screw with it any more recently :P

I will bite the bullet in the next month or 2 and give it to the highly regarded Subaru performance guys in my city so they can put it on the dyno and screw around with it while charging me an arm and a leg. I am 90% sure they won't be able to solve it either... hence why I've held off so long lol.

But if I ever solve it, I will report back too!
I'm close to doing the same (dyno testing). I've had a second set of new plugs put in, and they were gapped down to .25 from .28 (NGK Iridium OEM spec heat range). I've unplugged the MAF and ran straight MAP, and the event still occurs. Logging shows the IM going full vac despite requested throttle input and despite going full vac - the BPV doesn't release which may mean the IM is not under vacuum. Next step will be replacing the MAP sensor with a known working one to rule that out.
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Old 02-22-2013, 08:36 AM   #78
GGSimpreza
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Quote:
Originally Posted by jaymmmbee View Post
I'm close to doing the same (dyno testing). I've had a second set of new plugs put in, and they were gapped down to .25 from .28 (NGK Iridium OEM spec heat range). I've unplugged the MAF and ran straight MAP, and the event still occurs. Logging shows the IM going full vac despite requested throttle input and despite going full vac - the BPV doesn't release which may mean the IM is not under vacuum. Next step will be replacing the MAP sensor with a known working one to rule that out.
Keep us posted. This problem sucks.
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Old 02-25-2013, 01:46 PM   #79
jaymmmbee
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Update for me. I've resolved my issue!

I ran a known good MAP sensor and the event still occurred. This pointed towards a post MAF/Pre turbo issue with prior troubleshooting steps. Turbo inlet was fine but the post MAF section of my OEM intake was suspect (was running the Venair silicone piece - which is way too soft, never had issues with an AVO piece I had prior). Turns out it was sucking shut at full load starving the turbo of air. This only occurred under boost/WOT conditions just over 5K RPM. Put in an OEM post MAF section of the intake and it's been trouble free for a couple hundred miles! I'll be sticking OEM unless I go to a bigger turbo requiring an aftermarket big MAF intake. Took about 5K miles for the Venair piece to begin to fail.

Hope you guys get to the bottom of your issue and perhaps this is something worth looking into (post MAF to turbo intake section collapsing or major leak).
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Old 02-26-2013, 03:14 AM   #80
Merko
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Quote:
Originally Posted by jaymmmbee View Post
Update for me. I've resolved my issue!

I ran a known good MAP sensor and the event still occurred. This pointed towards a post MAF/Pre turbo issue with prior troubleshooting steps. Turbo inlet was fine but the post MAF section of my OEM intake was suspect (was running the Venair silicone piece - which is way too soft, never had issues with an AVO piece I had prior). Turns out it was sucking shut at full load starving the turbo of air. This only occurred under boost/WOT conditions just over 5K RPM. Put in an OEM post MAF section of the intake and it's been trouble free for a couple hundred miles! I'll be sticking OEM unless I go to a bigger turbo requiring an aftermarket big MAF intake. Took about 5K miles for the Venair piece to begin to fail.

Hope you guys get to the bottom of your issue and perhaps this is something worth looking into (post MAF to turbo intake section collapsing or major leak).
You know this seems like a very real possibility! Just watched a vid of a guy with his car behaving the same way and it turns out that was his problem.

My intake is all OEM except the 90 degree elbow coming out of the VF34. This is from a rubber hose store. I had a quick look just now for any evidence of it squishing, but couldn't see due to limited access. I'll have a better look on the weekend, and maybe try reinforcing the hose with a few hose clamps to see if it behaves any differently.

Fingers crossed!
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Old 02-26-2013, 10:14 AM   #81
DHRDAN
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it's not your coil packs. idiot.


you're hitting fuel cut off. christ.
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Old 02-26-2013, 01:51 PM   #82
jaymmmbee
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You're a real gem DHRDAN - no wonder I avoid this forum typically.

Good luck MERKO. I'll watch to see if that piece ends up being the issue. Mine was clamped well, but under load it literally sucked shut.
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Old 02-26-2013, 02:11 PM   #83
GGSimpreza
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Quote:
Originally Posted by jaymmmbee View Post
Update for me. I've resolved my issue!

I ran a known good MAP sensor and the event still occurred. This pointed towards a post MAF/Pre turbo issue with prior troubleshooting steps. Turbo inlet was fine but the post MAF section of my OEM intake was suspect (was running the Venair silicone piece - which is way too soft, never had issues with an AVO piece I had prior). Turns out it was sucking shut at full load starving the turbo of air. This only occurred under boost/WOT conditions just over 5K RPM. Put in an OEM post MAF section of the intake and it's been trouble free for a couple hundred miles! I'll be sticking OEM unless I go to a bigger turbo requiring an aftermarket big MAF intake. Took about 5K miles for the Venair piece to begin to fail.

Hope you guys get to the bottom of your issue and perhaps this is something worth looking into (post MAF to turbo intake section collapsing or major leak).
My MAF housing is connected to my inlet with a soft silicone piece too. I need to find a hard rubber OEM like elbow to try, and then I'll let you know!
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Old 02-26-2013, 05:52 PM   #84
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Quote:
Originally Posted by jaymmmbee View Post
You're a real gem DHRDAN - no wonder I avoid this forum typically.

Good luck MERKO. I'll watch to see if that piece ends up being the issue. Mine was clamped well, but under load it literally sucked shut.
As in you tried to reinforce it with more hose clamps and it still collapsed?
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Old 02-27-2013, 04:40 AM   #85
Merko
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jaymmmbee I ****ING LOVE YOU!!!!!!!!!

IT WORKS

As the VF34 doesn't have the 90 degree elbow that the stock TD05 has, we put in this rubber elbow. Seems it was a bit too soft!! though the bloke that put it in has used it in many other rexes with no problem. I must be unlucky! Anyway, I put on a hose clamp diagonally as seen in the pic, set it to 15psi, and BOOM IT REVS ALL THE WAY

Thank you so much dude, this has been killing me for like 8 months. Finally I have a fun rex ^_^

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Old 02-27-2013, 01:07 PM   #86
eg33GC
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woohoo

any reason you ditched the 16g?
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Old 02-27-2013, 05:47 PM   #87
Merko
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The td05 was dying. Got the vf34 fairly cheap and with low mileage. It's way better though, significantly less lag than the td05.
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Old 02-27-2013, 06:29 PM   #88
V62.5rssti
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What turbo is factory on a v6 sti Type ra?
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Old 02-28-2013, 02:58 AM   #89
Merko
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15 seconds of Googling said VF29 mate :P

The VF34 is off a bugeye STi. Unsure of exact model/year.
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Old 02-28-2013, 11:30 AM   #90
jaymmmbee
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Congrats Merko! Glad the fix I did resolved your issue as well! I only had to deal with this for a month or so - 8 months is a long time. Hopefully this resolves GGSimpreza's issue too!
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Old 03-01-2013, 08:13 AM   #91
GGSimpreza
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Quote:
Originally Posted by V62.5rssti View Post
What turbo is factory on a v6 sti Type ra?
Get out. Now.


Quote:
Originally Posted by jaymmmbee View Post
Congrats Merko! Glad the fix I did resolved your issue as well! I only had to deal with this for a month or so - 8 months is a long time. Hopefully this resolves GGSimpreza's issue too!
I'M GONNA PEE MY PANTS! (i haven't tried it yet, I need to find a stock elbow from somewhere I suppose. Any suggestions?)

But if it works I'M GONNA PEE MY PANTS!
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Old 03-01-2013, 08:16 AM   #92
GGSimpreza
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Originally Posted by Merko View Post

Is it bad that I really don't mind how dirty my engine bay is? Dad raised me on power > aesthetics

Love your residual coolant and stuff haha.
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Old 03-01-2013, 06:13 PM   #93
Merko
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Hehe yeah couldn't care less for how it looks as long as it works :P there's hoses all over my engine bay for pcv valve to oil catch can and the head breathers. Want it to be as legal looking as possible even if it's messy. The only blatantly visible illegal mod are the coilovers. Need to get rubber caps to hide the stiffness adjustment knobs. Sleeper spec for the win yo!
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Old 03-04-2013, 01:12 PM   #94
jaymmmbee
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Well I'm anal about a clean bay, but know it isn't necessary for functionality. Here's mine with the POS Venair silicone post MAF tube that was the cuprit (now the OEM piece is in place which remedied the issue).


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Old 03-15-2013, 05:52 PM   #95
GGSimpreza
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Okay. So I replaced my elbow with a stock piece and....it made the problem better. I can run higher RPM before the car freaks out.

Just a note: My elbow WAS NOT collapsing, causing this issue. Subaru's are picky about intakes it seems, and just didn't like the material, or where the MAF was, because now it's 2-3 inches closer to the fender.

I know it wasn't collapsing because the space between the turbo inlet and my maf housing (so the only place that wasn't around plastic) was only about 1.5 inches. It's impossible for it to collapse. Also, it's an expensive reinforced silicone elbow, not some eBay junk.

I'm convinced the car didn't like how air was pushing through it or something.

One other thing to note: I have an aftermarket cone filter hooked to my MAF housing. I bought just the motor, and it didn't come with the stock airbox. I will try to rig my stock RS airbox up and see if that fixes it next.

Or does anyone know where I can get an old late ej20g airbox or ej20k airbox? Maybe old Leg turbos also had the same box?

It's better, but not fixed. I'll keep you guys updated.
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Old 04-01-2013, 10:41 AM   #96
NewWRXMike
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Congrats on fixing the problem. Really strange problem, I'm glad you figured it out!
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