[rednbmx5]

So Ive searched for a similar issue for quite a while, turned up a lot of 04 WRX's, none really of the 09+ WRX.

14 WRX:
Stock Intake, New air filter
Bellmouth 3in DP Catless
Magnaflow CB
Cobb AP V2/Stage 2 91 HWG

Datalogs on my Google Drive: https://drive.google.com/open?id=0Bx8XZZUmuv8zM21zN2ZLV0FDdzQ

I was on the NWG tune before and was only getting up to 14.5 psi, tapered off to 11 towards redline. Now with the HWG it gets up to 15 psi, then tapers to 11-11.5. Datalogs are attached.

Datalogs show no knock, one thing I did see was that at lower RPM's when I get a little on the throttle the WG duty cycle will go to 70-80%, but when im at the 3500-4500 RPM floored where peak boost should occur the WG duty cycle will only get up to the mid to high 50%. Would this be the tune itself?

I have no boost leaks, pressurized the intake with 25 psi from my air compressor and it held strong. Both stock restriction pills are in there. Intake temps are great.

Any help would be great!

 

[MainFrame]

According to Cobb's map notes for that map you are hitting boost target for Sport mode. Peak boost target for mode on the ACN91 map is 15psi, +/-1psi, and for the regular 91 octane map it is 15.5psi, +/-1psi. Are you logging in Sport, or Sport Sharp?


As far as the WGDC tables, you are correct, they are all set in the tune.

 

[rednbmx5]

According to the notes it should be 17.5, it shows that on my AP as well before I flash a tune on the car. Idk what you mean by Sport or Sport Sharp, are you referring to the DCCD in an STi? My car is just a base model WRX.

 

[zax]

Log TD Boost error

I'll get around to plotting your boost curve when I'm at a PC

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[zax]

Also, your profile indicates you live in Boise, ID. Boise is around 3000' elevation so expect roughly 1-1.5 PSI lower target boost.

I'll look at the PSIa comp table when I have access to your map.

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[rednbmx5]

Really? I would expect that the ecu would compensate for the elevation if its a true closed loop boost control. The TD error is logged on my datalogs i have posted in my google drive. TD error is as much as 3 psi at times.
Alright let me know what you find out and thanks for taking the time.

 

[zax]

Really? I would expect that the ecu would compensate for the elevation if its a true closed loop boost control. The TD error is logged on my datalogs i have posted in my google drive. TD error is as much as 3 psi at times.
Alright let me know what you find out and thanks for taking the time.

It, does, but it won't break the laws of physics.

The ECU is attempting to optimize the exhaust flow through the wastegate in order to keep the turbo in the correct efficiency range.

Turbo efficiency is represented as the flow through the closed loop system with respect to a pressure ratio (PSIa/PSIr). Since the ambient pressure is lower, PSI absolute is lower therefore also PSI relative (boost).

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[zax]

Short story: the ECU does compensate hence the lower target boost.

I'll look at the datalogs when I'm in front of a PC. We are looking for the steady-state TD boost error. It should approach and hold zero once peak boost has been reached. Subaru uses TD boost error during spool to keep turbo dynamics active for fast spool.

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[zax]

Checked your boost trace, and the curve looks normal.

You consistently have approx. 2 PSI of TD Boost Error which suggests the system is unable to achieve target boost (which is around 16.3 at peak with atmospheric comps).

I need to look a bit more at the data, but it seems you may have a mechanical issue here. Have you checked the TMIC-TB coupler? Check also that the WG arm isn't loose. If you can, please cruise around logging your Long Term Fuel Trims (LTFT). I'd like to see data from all airflow zones.

 

[rednbmx5]

Wow zax really appreciate all the help man. Ok ill make a datalog of just driving around and upload that for you. I just had the TMIC off when i drained+refilled the trans. Made sure to put it all together correctly and did the boost leak test afterwards. I also pulled off the vacuum lines that run to and from the boost control solenoid and blew air through them to make sure they are clear, which they were. Wastegate arm appears to be tight. Vehicle has 38k miles on it, just for gee wiz dont know the longevity of these solenoids.

 

[rednbmx5]

Checked your boost trace, and the curve looks normal.

You consistently have approx. 2 PSI of TD Boost Error which suggests the system is unable to achieve target boost (which is around 16.3 at peak with atmospheric comps).

I need to look a bit more at the data, but it seems you may have a mechanical issue here. Have you checked the TMIC-TB coupler? Check also that the WG arm isn't loose. If you can, please cruise around logging your Long Term Fuel Trims (LTFT). I'd like to see data from all airflow zones.

https://drive.google.com/open?id=0Bx8XZZUmuv8zS0dwRGZ5c3l5dlE

Some cruising and a highway pull, it held a consistent 14.5 upwards of 5500rpm. Thanks again.

 

[zax]

Learning looks fine.

Still could be a boost leak though.

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[rednbmx5]

What are other areas that a boost leak could occur? Just removed the TMIC again. Took off the tube going from IC to TB, was tight and no holes. Oring on IC looks good as well. Recirc valve not holding?

 

[irickchad]

Just to point out, you're also running a map made for a catted downpipe. You're not only running catless, but bellmouth, which could theoretically effect boost levels

 

[zax]

Just to point out, you're also running a map made for a catted downpipe. You're not only running catless, but bellmouth, which could theoretically effect boost levels

I can't think of a single aftermarket DP that isn't bellmouth.

Good catch on the catless DP, didn't see that. The high elevation probably would reduce the chance of boost creep, however.

 

[irickchad]

I can't think of a single aftermarket DP that isn't bellmouth.

Good catch on the catless DP, didn't see that. The high elevation probably would reduce the chance of boost creep, however.

There's plenty that aren't, and most of the ones that are bellmouth still have the divorced wastegate plate in there. My Grimmpseed isn't bellmouth, for instance. It has a separate runner for the wastegate.

 

[rednbmx5]

Ok i put the car back together. Installed the TB to IC hose without the "problematic" sleeves that come on 11+ wrx's. Little colder tonight did a few WOT pulls and it peaked at 15.8 the highest. Bellmouth DP could effect the opening of the WG flap, being the pressure of the exhaust from the turbine exit is more exposed. Essentially increasing the chance of boost creep no?

 

[zax]

The DP has no effect on the wastegate flap. Recall, the oem DP is a flat plate design.

I disagree with irikchad. The bellmouth design has been the de facto accepted design over the years. The divorced design is an exception to the rule.

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