What intake is on the car? Cobbs map requires their brand SF intake. If you have another brand intake on there (aem, perrin, GS) and think that the cobb intake map will work you are wrong. If you do indeed have the cobb sf intake, then contact cobb. Along with their map, accessport, and parts you get their customer support.

 

I have a Perrin intake and just got my Cobb access port today. I was getting -5.6 FKL and .625 DAM with just the stage one tune. Switched to stage 1+ big SF and problems were solved. 1.0 DAM and the usual random -1.14 FKL.

 

Thats not how this work, that tune explicitly states it only supports the cobb intake. The following is why this is important and was recently posted AGAIN by zax

ANY ICE requires proper metering of air and fuel in order to properly function. In the carburetor days, this was accomplished using jets and "signal" (the pressure of the air during and after the venturi).

With the advent of fuel injection, it is necessary to determine the amount of air ingested by the ICE in order to deliver the correct quantity of fuel. There are different approaches to this, but by and large the most common are to use an MAF sensor OR airflow density monitoring (IAT and MAP sensors). Since modern Subarus are MAF-metered from the factory, we will focus on that approach.

An MAF works by measuring the loss of heat energy from an energized wire. This is determined by the change in the resistance of that wire which can be correlated to the energy loss from that wire. In a closed and laminar-flow system, the loss of energy from that wire is dominated by the speed of the airflow in that system. The car's ECU can accurately estimate the air consumption of the ICE by closely monitoring the change in resistance (and thereby voltage in a constant-current circuit) of that energized wire (MAF sensor).

The trouble is that the MAF sensor does not DIRECTLY MEAUSURE airflow, but correlates airflow to voltage through a calibration table. There are many things that can change the calibration -- most notably the diameter of the MAF sensor housing, the placement of the MAF sensor within that housing, and the airflow characteristics around the MAF sensor (eddies, currents etc.).

While it is true that under low engine loads, the CLOSED-LOOP fueling algorithm which involves oxygen monitoring hardware in the exhaust will compensate for scale errors, closed-loop fueling is limited in what it can correct. Under the right circumstances, the ICE may run dangerously rich or dangerously lean and both conditions can cause irreparable engine damage. Lean conditions may cause engine knock and burned valves due to high combustion temperatures. Rich conditions (while typically safer) can cause cylinder washing, oil dilution, and eventual damage to the bearings.