New to this site, looking for a little guidance
 

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?

Welcome...

Matt @ KSPEED can help you with a tune. Check the vendor forum.

Your intake might be part of the issue. That is a lot of mods for an off the shelf map!

14-15PSI sounds about right for that map but no way to be sure without seeing the tables. I think flutter is often caused by not enough WG duty cycle for the ECU to control it and wastegate is triggering on spring pressure and then not and then is and then not...

By AP do you mean Cobb Access Port? V1 or V2? Is that a Cobb map?

Yes, it's a Cobb AP V2, OTS Map. The notes are here: http://www.accessecu.com/accessport/...N91%20v100.pdf

This map is specifically for use with cobb SF intake, so I didn't think there would be a problem there. But then again?

Too many mods for OTS? Perhaps. That's why I ended up here, I guess.

OK, maybe that should work pretty well given your mods.

Assume you flashed that as a base map and reset the ECU.

Is there a HWG version of the map? Assume it is missing targets in 4th and 5th. 1,2, and not sure about 3 on a 5sp.

Even with the Cobb intake it will take a while to learn your new setup after reset.

Unfortunately there is no HWG version for this map or I would have tried it.

After I load the base map, isn't ECU reset automatically performed by the AP in the flash sequence?

Seems like a lot to "learn" to me is all. You think I should just drive it around for a while? It's not throwing codes or showing any other bad signs (other than normal increased spoolup noise as a result of the intake).:?:

and thanks for your help

Not sure, but I always reset after any base flash just to be sure.

Since it is for the WRX, I wonder which pill the map is expecting? Might be worth trying the WRX pill/hoses.

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

Doh. Not having done any tuning in 2 years, I could not remember which way was which. This is one of the backwards ones. less is more.

His 16bit ECU is more sensitive to max. WGDC settings than your 32bit ECU. And no, more WGDC = more boost. But if the WGDC's are set too high the boost will overshoot and fluctuate on a 16bit ECU. Whereas on a 32bit ECU it tends to overshoot and settle near target boost. Just in general anyway...

MUCH better after swapping out the pill from the td04. WG fluttering seems to have stopped and the car is much smoother at WOT, especially 3rd & 4th gear pulls. Seems to sustain that 15.5-16 psi you mentioned, but no higher. This is going off the stock Lamco gauge, I wasn't logging anything this morning. I think I'll drive it for a few days and see what happens.

Welcome! Consider a Hallman Pro RX MBC before a custom tune, if you decide to go that route. Or here's a local deal on an EBC: http://seccs.org/forums/showthread.php?t=9169. I feel the stock boost solenoid holds the boost response back by quite a bit, especially at this elevation with a 2L and larger turbo.

Hope you stick around. :)

Glad to hear you got a fix! welcome to the site! :D

It would be interesting to know what pill you had. A VF39s off any STI should have had the fairly large pill. The VF43s in '07 had the small one. The TD04 should definitely have the large 1.2mm one though. Glad that helped.

Pill sizes...
http://legacygt.com/forums/attachmen...6&d=1193682267

Question by looking at your mod list. Are you still using the stock wrx fuel pump?

And welcome!

Good question. Stock might be OK for VF39, but just barely. WRX 130lph vs. 145lph for the STI stock. Walbro is cheap insurance.

Thanks for the warm welcome guys.

Right now I still have the OEM unit in there, but ordered a Walbro 255 just to be safe.