Unhappy 2009 XT - no codes

My 2009 OB XT is not a happy car right now. Idle has been rough at initial startup in the morning (FAST idle 1500rpm) as the car shakes and the rpms do visibly move a couple hundred rpm. Once it warms up it idles like any other Subaru. Recently the car has started backing off under boost - Boost hits target but during a third gear pull you can feel the car backing off 10-15% of its power for a half second. A few occasions show knock but most of the time nothing.

 

Logs sent to the tuner reveal nothing (occasional -1.4 learned knock correction but its not always there). In the last few days the car idles even worse and tonight you can see the tach visibly moving 150 or so rpm up and down and you can feel it.

 

Logging Cylinder Roughness and misfires reveals ZERO's. If you get into the gas at all and hit boost it goes, then acts like a fuel cut but without the violence. Its like it doesn't have enough fuel and then it does. This happens at partial throttle in some cases as low as 2500rpm but without the extreme power loss.

 

Did a boost leak test last weekend and it holds 5psi for well over 40 seconds, 10 psi took nearly 90 seconds to bleed off which the other posts I've read say I've got no leak.

 

Learning views show column one in the negative 6-10 range depending on when you pull. The other column are all within 3. Tuner says has fueling problem written all over it.

 

I'm on a BNR 18G, DW65c pump, DW750cc injectors, PW TMIC, and a KS-Tech intake. Before I start throwing money at things does anyone have an ideas or simple troubleshooting steps before I start yanking pumps, injectors, etc?

 

 

Jeff

Kind of what mine was doing. No random CEL's?

I thought mine was the ECU. The local Subaru shop diagnosed it as the BIU. Body integrated unit. This is the box that controls EVERY function of the car except engine functions.

No random CEL's - No CEL"s at all. Does The BIU sound likely seing as the problem seems engine/fueling related?

I would think a faulty BIU would generate codes.

both 02 sensors good?

The 2nd doesn't really do much with a downpipe right? And once we hit wot doesn't the front o2 sensor stop controlling afr?

I would also think, that a bad, or going bad, o2 sensor would throw a code if it was performing crappy enough to cause noticeable driving issues.

some tunes tune out the rear 02 sensor. so when it fails you don't get CEL

I don't think Bren tunes it out...

So.. I had a Bren tune via open source that may or may not have had p0420 turned off. We recently swapped to a Cobb tune with no changes and not 50 miles in i got a p0420 and the car ran horrible. Bren sent me a map with a p0420 delete and life was better.

 

Mike at Infamous has indicated the cnt downpipe loses its catalyst efficiency after a couple years and mine is now almost 2yrs old.

 

That being said i guess it's possible the cat finally degraded enough to kick out a p0420 coincidentally.