Here is the background. I have a 2006 STi, I purchased a Tactrix cable, downloaded RomRaider and ECUFlash, plugged in and made sure everything was working correctly and it is. I was able to read the stock program, blah blah blah.

My point.... I logged a run of my car completely stock to have for comparison. I then installed a catless downpipe, catback exhaust and a cold air intake. I took the car out for a drive and logged my drive. On a quick 2nd gear pull I logged 18.4 psi of boost and 111% duty cylce on the injectors. That troubles me. I am going to get a wideband so I can verify afr but in the meantime I want to reduce the boost in hopes that will bring my injector duty cycles back down. When the car was stock it made 11 psi of boost and 84% injector duty cycle. I went into the target boost tables and reduced the target from 14.5 to 12.5 at 80% throttle and reduced the wastegate duty cycle by 10-15%. I then flashed the computer and took it out for a test drive. No change! What am I missing? Went through all 4 target boost tables and all 4 wastegate duty cycle tables multiple times with no changes. Is there a point to where the wastegate cannot reduce the amount of boost? It can only increase? Thanks for any help!

Set the entire WGDC initial and WGDC max table to 0.

Log it.

Then adjust your WGDC from there.

Make sure your boost target table represents what you actually want.

So by setting the WGDC initial and max tables to 0 the computer will "default" and control boost off the target boost table? Correct?

Next question, once I do that do I then adjust the target boost table if the boost isn't what I want? Or do I add 5-10-15% duty cycle to the wastegate duty to reach my target boost?

Thank you very much for your input.

Zeroing those tables effectively disables the wastegate. You'll be running on wastegate spring pressure alone, so you'll still see some boost.

Then just follow mick's instructions. Set boost targets to what you want, but what is physically possible.

Also consider turbo dynamics.

Get Airboy's spreadsheet: http://www.romraider.com/forum/topic957.html

And read this, its a mouthful, but it contains everything you need to know about the subaru BCS:

This is another area which can be confusing to new tuners, so I figured I'd outline how it works. There are actually two different versions that are used and both have important differences. Make sure you download and install the latest ECU and logger definitions so that you will access to the tables and parameters discussed below.

First some basics for both versions:
The ecu determines your boost target based on the 'Target Boost' table. The 'Boost Compensation' tables can adjust this target value based on a number of factors (ex. atmospheric pressure, intake temp, etc). This final value (post-compensation) is the level of boost the ecu will attempt to target. 'Boost Error' is determined as follows:

Boost Error = Target Boost - Actual Boost

As you can see, if target boost is greater than actual boost, boost error will be positive (you are undershooting your target). If target boost is less than actual boost then boost error is negative (you are overshooting your target). Boost Error is used as input to the 'Turbo Dynamics' tables.

The 'Turbo Dynamics' tables make corrections to wastegate duty based on boost error in an attempt to hit target boost. The percentage correction shown in the tables is absolute. That is, if your wastegate duty was 10% and the turbo dynamics correction was 5%, then your wastegate duty would then be 15%. Between the two versions, there are noticeable differences between how these tables work and this will be outlined below.

'Initial Wastegate Duty' and 'Max Wastegate Duty' both have the same compensation tables associated with it. That is, the various 'Wastegate Compensation' tables you see in RomRaider for atmospheric pressure, IAT, etc are applied to both of these tables.

Version #1 (USDM 02-05 wrx and 01/02 non-USDM models)

This version can be identified by the names of the turbo dynamics tables (burst and continuous). It also has a 'Max Wastegate Duty' table but it does not have an 'Initial Wastegate Duty' as other roms do.

The correction from the turbo dynamics (TD) tables in this version is simply added to wastegate duty and limited by 'Max Wastegate Duty'. However, the TD tables are not active unless certain thresholds of boost error are met as determined by the 'TD Burst Activation Thresholds (Boost Error)' & 'TD Continuous Activation Thresholds (Boost Error)' tables.

The 'Turbo Dynamics Burst' table is the least used of the two correction tables. It is only active when boost error swings extremely quickly from negative to positive or vice versa (outside the range determined by the activation thresholds). Otherwise, it does not come into play. The 'Turbo Dynamics Continuous' table is active a lot of time. Anytime there is negative boost error or boost error is positive (outside of the disable ranges determined by the activation thresholds) it will act to correct wastegate duty (as long as wastegate is not being cut by other factors such as the speed limiter or idle).

However, wastegate duty can never exceed the values determined by the 'Max Wastegate Duty' table (post-compensation). In addition, actual wastegate duty will never exceed 96% on these ecus, regardless of what value you are logging as 'Primary Wastegate Duty'.

You can log the current correction through the 'Turbo Dynamics Burst*' and 'Turbo Dynamics Continuous*' extended parameters. In addition, you can also log 'Boost Error*' and 'Target Boost*' (post-compensations).

Q: So if there is no initial wastegate table, how does the ecu know what wastegate duty to start with?
It doesn't. Let's say you start at idle where wastegate duty is zero regardless. Then you take off and jump on the throttle. Boost error will be positive and large. The 'Turbo Dynamics Continous' table will use the largest positive correction value since the boost error likely exceeds the last row's value. It will keep adding this correction (ex. 3.14%) to wastegate duty over and over until either you are near the current target boost or you hit max wastegate duty. Correction will taper down as you approach target boost and boost error becomes less and finally no correction is added when boost error is within the disable activation range.

Version #2 (All 32bit ecus and 03+ non-usdm 16bit ecus)

This version adds an 'Initial Wastegate Duty' table. TD tables consist of Integral Positive, Integral Negative, and Proportional.

There are rpm and target boost thresholds that must be met before active TD correction as determined by the 'TD Activation Thresholds (RPM)' and 'TD Activation Thresholds (Target Boost)' tables. In addition, there is a minimum positive boost error (usually very small) before integral positive correction is allowed as specified by the 'TD Integral Positive Activation (Boost Error)' table. Integral negative correction is typically only used when there is negative boost error as determined by the 'TD Integral Negative Activation (Boost Error)' table. TD Proportional is active anytime the rpm and target boost thresholds are met, regardless of boost error.

Instead of adding TD corrections directly to the current wastegate duty, as in version 1, version 2 adds the correction to the Initial Wastegate Duty value (post-compensation). This final calculated value (with TD correction), however, is limited by the 'Max Wastegate Duty' table (post-compensation) and it will never exceed it. In addition, regardless of the 'Max Wastegate Duty' value, the final wastegate duty will never exceed the cap imposed by the 'Wastegate Duty Limit (Maximum)' table (32-bit ecu only). The final value then becomes your current wastegate duty (there are other differences in certain roms, but this is the normal behavior).

The TD Integral correction is different in that it can accumulate over a certain range. That is, the correction is accumulated until target boost OR rpm drops below the activation disable thresholds, at which both the TD integral cumulative and TD proportional values will be cleared. In addition, the TD integral cumulative value is limited to a specifc range as determined by the 'TD Integral Cumulative Range (WG Correction)' table. Also, if current wastegate duty is greater than or equal to max wastegate duty, the 'TD integral positive' table is disabled. That is, no additional positive correction is added to the TD integral cumulative value (although the cumulative value could still be positive).

There are some other minor differences between the 16bit and 32bit ecus for this version, but nothing worth elaborating on.

You can log the current correction through the 'Turbo Dynamics Proportional*' and 'Turbo Dynamics Integral Cumulative*' extended parameters. You can also log 'Boost Error*' and 'Target Boost*' (post-compensation).

Wow, you weren't kidding, that is a mouthful. Thanks though, very informative! I will make small adjustments tonight and see how it plays. I am only targetting a boost level of about 14-15 psi. Anything to keep my injector duty cycles less then 100% so it is "safe" to drive until I get it tuned. Thanks again.

Boost control is a closed loop system.

You can pick and choose your boost at whatever rpm you want.

If you are hitting 100% IDC, then you should limit boost at that rpm and drop it above that rpm to keep your IDC a constant 100%. However, there is no need to hurt your performance unnecessarily at the lower rpm. I bet you could still run 19 psi at 3200 rpm with no problems.

The first thing to tuning boost is to datalog 0% WGDC. That sets your baseline. It also tells you if you have any mechanical problems or if you have any creep issues. Under theoretical ideal conditions, the boost curve will be flat and will be equal to your wg spring load.

If you have boost control problems with 0% WGDC then you will need to try swapping restrictor pill to a larger diameter or changing the actuator spring pressure or as a last resort... port the turbo.

BTW, the 32 bit ecu boost control is awesome. Boost control needs to be a feedback control loop system because the amount of WGDC needed to hit target boost is a function of how the engine arrived at that particular rpm and throttle position. WGDC initial sets up your minimum baseline and turbodynamics adjusts it to hit the correct WGDC up to WGDC maximum. Carefully dialing in WGDC initial and Turbodynamics will allow you to control boost in all gears as well as 2-3-4 shifting. It takes a lot of time.

Well I took a long lunch today and set target boost to 14.5 psi at 80% throttle, zero'd the WGDC initial and max duty cycles. A quick 2nd gear pull resulted in 17.9 psi of boost and 109% injector duty cycle. The other thing is it definitely affected cruise. It developed a pretty substantial surge at 1800-2200 rpm cruise. I would have no problem adding wastegate control at everywhere less then 80% throttle but above that should I reduce the Target boost to 12.5 or less and see how that effects it? I don't understand why everything I change has no effect. Is it possible that because there is no backpressure on the wastegate that it is "out of control" so to speak?

You have a mechanical issue. Changing the target boost will have no effect.

Make sure that everything is hooked up correctly. Check that all the BCS hoses are hooked up. The restrictor pill is in the correct location.

After you check all the hoses, hook up a pressure source to the actuator and check to see what pressure the actuator arm starts to move. Also try to measure how much total travel it can move.

And if the BCS is working properly, but you still have the mechanical spike/creep.. a couple things you can look into are wastegate porting, external wastegates, or running a catted exhaust.