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05 OBXT Manual, 05 3.0R OB Manual (Moded, R.I.P.)
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Discussion Starter · #1 ·
I recently went stage 2 on my '05 obxt. Currently installed is: invidia catless up-pipe, cobb catted downpipe, and cobb CAI. Also worth noting is I have a non-oem catback exhaust without a resonator, but still a y-pipe style out to non-oem mufflers, however diameters are oem. Purchased the vehicle with it on already, definitely going to be replacing eventually.

Anyways, I'm running a cobb stage 2 + sf v300 on 91 normal wastegate and am missing boost target by about 3.5psi. I'm running v300 because my cobb DP is older and doesn't have the new GESI cat, so I pop p0420 on v400. I have tried v400 normal and HWG though just to see. I get pretty much the same results in my logs with any of the tunes. I have a log here and just want to see if anyone has suggestions on where to start searching since nothing is jumping out at me.

I have done a 120K service on the vehicle, and removed the intake manifold, replaced quite a few gaskets and o-rings, new spark plugs. I wasn't able to do all of the vac lines I would have liked, but I did not see any obvious cracking. My intercooler appears fine as well. During DP install I checked my turbo and it felt really solid, wastegate also looked good. Also, my A/F learning A,B,C are all within +/- 5 range...so I'm kind of stumped. But maybe i should just go ahead with a boost leak test?
 

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05 OBXT Manual, 05 3.0R OB Manual (Moded, R.I.P.)
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Discussion Starter · #5 ·
I guess you found an older map? Cool!
Haha I did! I dug around and found an older one, so no p0420 code popping, but alas now I have this issue which is irritating the **** out of me…probably gonna get under the car this weekend to double check all of my work and move to a boost leak test. I really regret not datalogging on stage 1, but didn’t feel the need since my boost always seemed correct for my elevation+conditions and fuel trims were good. At 6000’ With stage 1 hitting 10.2ish psi where target was likely around 11.5psi. So maybe I had a tiny boost leak there that has become more apparent with stage 2?

But yeah since I’ve already gone stage 2 without fully investigating stage 1, I now just have that more to check out, lessons learned for sure.
 

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05 GT wagon, 09 Spec B, 18 3.6R Outback
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A boost leak test was my thought too.

Have you zip-tied all vacuum lines ?
 

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Discussion Starter · #8 ·
A boost leak test was my thought too.
For sure, worth doing just to rule things out. But here's what sort of throws me for a loop, my AF values aren't that off. I would think with a boost leak I would be seeing AF values being pretty off and positive? I'm seeing negative AF values within the 0 to -5 range. Or is this not necessarily true/I'm not thinking correctly?

Did you upgrade your turbo inlet pipe? Mine is pretty worn out but I have the Cobb one to put on at some point.
Yeah during my 120K service I noticed the turbo inlet was starting to tear pretty good at that hose clamp. I had a cobb inlet, but one of the inlet hoses wasn't connecting properly, think some hardware was missing or was sent the wrong one. Man I was so pissed at the time, cause I HAD to have the car running the next day so I had to run down and get a new stock inlet. Super annoying cause I know how much of a PITA the inlet can be without the intake mani removed, so yeah double payed and double worked lol.
 

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Discussion Starter · #9 ·
Hadn't been driving much, so just got back to maintaining it. Upgraded to a GS TMIC, stock one was definitely leaking a bit, and gained a fractional amount of boost, but didn't solve the issue. Then replaced a ton of vac lines and found the issue. The wastegate to turbo hose (one with the T and restrictor pill) was not stock and was some crappy "aquarium-like" tubing with no restrictor pill. Admittedly, I should have checked that line out way sooner, but that was definitely the issue. Now getting the correct amount of boost and good fuel trims :)
 
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