Quote:
Originally Posted by bss
Hello there. I found this site while I was searching for someone to possibly do an open source tune for me in the Reno area and ended up hitting on a few of the pages on this site. I had no idea there was an active Subaru community around. Pretty Cool. Anyways, hopefully someone will have some suggestions cause I'm in a jam and this is my wife's car! Doh.
I've always owned and worked on my own Subarus (98 OBS, 84 GL, 87 GL, 04 WRX) but this is my first turbo car and while I consider myself fairly handy with a wrench (can do most all medium-duty maintenance without help, rebuilt 2 motors from the book), I may have gotten a little overzealous on this one.
I put an VF39 and some pinks on my car this weekend and while it runs (no leaks, woohoo) it seems like maybe the wastegate is slipping open prematurely or something? Reflashed with AP VF39 /565 Pink CA/AZ/NV 91 octane base map. VF Turbo has stock VF39 WG., and used new UP/DP gaskets.
I am using the vacuum T that came with the VF39, so I'm assuming it has the VF sized restrictor pill.
Other mods are
STI tmic
Perrin inlet, afta maf
Cobb SF intake
Perrin lightweight pulley
Invidia UP
Invidia DP, Borla hush cbe
When boost hits up between around 15-17lb, the turbo kind of "slips" and flutters, the boost needle just fluctuates back and forth, then boost seems to drop off and hold right around 1 mpa again. Boost seems a little slow to build, but when spooling seems to hold boost alright until right around 14 pounds or so. Cobb target boost is 17PSI.
I have doublechecked all of my hose clamps and hoses, they all seem just fine, and worked fine with the td04. AP scan revealed no trouble codes.
any suggestions?
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The target boost is 17psi at sea level. Up here it is more like 15.5-16psi, because the ECU adjusts target boost with elevation. Boost will also taper off more at higher RPM up here.
OTS maps sometimes have trouble controlling boost at elevation, as they are usually developed at sea level. Cobb maps are usually pretty good, because their main facility is at 4500'-ish in Utah.
The 16bit WRX ECU's have a harder time controlling boost than the later 32bit ECU's. If boost is fluctuating then usually the wastegate duty cycles are set
too high (not too low, Dean) and/or the turbo dynamics settings are too much. It is possible the Perrin turbo inlet is causing this, but I doubt it. The STI intercooler and SF Intake are not the issue. Probably not a boost leak either. Could be the wrong size pill in the boost line, as there are 2 or 3 pill sizes that came on VF turbos. Yours should be a 1.2mm. If the turbo is off an 07 STI, then it definitely has the wrong pill (0.8mm) and a different wastegate and that is the problem. Or... you may just need to have the boost-related tables adjusted.
If you want a mechanical solution you could try drilling the pill out.
Do this in small increments (like 0.1mm at a time). If you need another pill we have several sizes here and usually give them away or trade for beer. Also can take a look at the car and log it to figure this out.
Matt