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Discussion Starter #1
Hey guys!

So, I have a 2013 Subaru WRX hatchback and I have been having these weird boost issues. Right now, I have the stage 2+ SF tune on it with the Cobb accessport. So I have a catless downpipe and an invidia exhaust along with the Cobb intake. I have been noticing that I'm only hitting about 13psi peak boost. I was having this same issue even with the stage 1+ tune. I have checked the throttle body to TMIC coupler and changed that out to a Mishimoto coupler. That still didn't help. I had it smoke tested, but without boost, and no one could find any leaks. I'm just not sure what else this issue could be stemming from. I'm supposed to be hitting ~18psi and I'm like 5psi away. I also like in Colorado at around 6,200ft elevation, but I don't think it would effect it that much.

Please help???
 

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Hey guys!

So, I have a 2013 Subaru WRX hatchback and I have been having these weird boost issues. Right now, I have the stage 2+ SF tune on it with the Cobb accessport. So I have a catless downpipe and an invidia exhaust along with the Cobb intake. I have been noticing that I'm only hitting about 13psi peak boost. I was having this same issue even with the stage 1+ tune. I have checked the throttle body to TMIC coupler and changed that out to a Mishimoto coupler. That still didn't help. I had it smoke tested, but without boost, and no one could find any leaks. I'm just not sure what else this issue could be stemming from. I'm supposed to be hitting ~18psi and I'm like 5psi away. I also like in Colorado at around 6,200ft elevation, but I don't think it would effect it that much.

Please help???
It can. I also didn't think Colorado had 93 octane.
 

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At 6200', your car won't hit close to the target boost at sea level.

If target boost is 18 PSI at sea level, that's 14.7+18 = 32.7 PSI MAP (2.22 PR)

At 6500', the ambient pressure is ~ 11.6 PSI, so MAP should be 2.22*11.6 = 25.7 PSI or a target boost of 14.1 PSI.

Seems like that altitude (and depending on the temperature and other comps) could yield a boost of ~13-14 PSI and still be "normal."
 

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At 6200', your car won't hit close to the target boost at sea level.

If target boost is 18 PSI at sea level, that's 14.7+18 = 32.7 PSI MAP (2.22 PR)

At 6500', the ambient pressure is ~ 11.6 PSI, so MAP should be 2.22*11.6 = 25.7 PSI or a target boost of 14.1 PSI.

Seems like that altitude (and depending on the temperature and other comps) could yield a boost of ~13-14 PSI and still be "normal."
I realized that this is not exact. Because the FLOW through the engine is also reduced at altitude, the engine may be able to target a higher pressure ratio. This is dependent on the compressor map (not public for the VF52). Short: the actual target MRP may be closer to 15.5 PSI compensated. Of course, there are additional compensations for IAT and ECT plus it depends on which gear you are in.
 

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Discussion Starter #5
So, is the boost I'm hitting around ~14psi okay then?? Or does it seem like something else is going on?? I just switched to a higher wastegate map and pulled again last night and got to like 13.7psi
 

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Do a log in 3rd gear 3000 RPM through 6000 RPM (be safe please) and log the following and nothing more:
1. RPM
2. Load
3. Throttle Position
4. Boost (manifold relative pressure)
5. Boost Target
6. TD Boost Error

Post the resulting CSV file here.

Also, per XJman's post -- please be clear on which map you are running (91 or 93 octane).
 

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Discussion Starter #7
I'm using the 91 octane Stage 2+SF HWG map.

Okay, I'll do this log and post it and see what you guys think.

Thank you so much guys!!
 

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I don't think Cobb's 91 map targets 18psi. Verify with the map notes and follow zax's advise.
 

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Discussion Starter #9
I don't think Cobb's 91 map targets 18psi. Verify with the map notes and follow zax's advise.
I read the notes for the map that I'm using and that's what it said though.

The map is 2013 SUBARU IMPREZA WRX MT STAGE 2 + SF MAP

Here is the map description verbatim:

DESCRIPTION
Stage2+SF 91 MTv331 High Waste Gate - Intended for an otherwise stock 2013 Subaru WRX MT vehicle running a turbo-back exhaust with a high-flow catalytic converter and COBB Tuning SF intake system. 91 or 92 octane fuels. Boost Targets: ~18.0psi peak boost pressure tapering down to ~13.0psi by the 7000 RPM redline, +/- 1psi. Higher wastegate duty cycle. Use if regular mapping produces less than desired boost levels.
 

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You're already not following the map notes for the calibration you're running...

I read the notes for the map that I'm using and that's what it said though.

The map is 2013 SUBARU IMPREZA WRX MT STAGE 2 + SF MAP

Here is the map description verbatim:

DESCRIPTION
Stage2+SF 91 MTv331 High Waste Gate - Intended for an otherwise stock 2013 Subaru WRX MT vehicle running a turbo-back exhaust with a high-flow catalytic converter
aortizme said:
Right now, I have the stage 2+ SF tune on it with the Cobb accessport. So I have a catless downpipe
 

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Discussion Starter #11
You're already not following the map notes for the calibration you're running...

I read the notes for the map that I'm using and that's what it said though.

The map is 2013 SUBARU IMPREZA WRX MT STAGE 2 + SF MAP

Here is the map description verbatim:

DESCRIPTION
Stage2+SF 91 MTv331 High Waste Gate - Intended for an otherwise stock 2013 Subaru WRX MT vehicle running a turbo-back exhaust with a high-flow catalytic converter
aortizme said:
Right now, I have the stage 2+ SF tune on it with the Cobb accessport. So I have a catless downpipe

Are you talking about the Catless downpipe?? This issue was happening even before the downpipe and exhaust swap. I was on the stage 1+ SF tune and was supposed to be getting 17psi and I was getting around 12psi.
 

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Are you talking about the Catless downpipe?? This issue was happening even before the downpipe and exhaust swap. I was on the stage 1+ SF tune and was supposed to be getting 17psi and I was getting around 12psi.
Yes -- Matty is right... that map is not compatible with a catless downpipe.

So you were having "problems" and further modified the car?

I'm still waiting for that log, but be aware that Catless DP concerns me. It won't cause an issue at altitude, but as soon as you drive closer to sea-level you will have gasflow issues through that OEM wastegate and will likely see boost creep.
 

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Discussion Starter #13
Yes -- Matty is right... that map is not compatible with a catless downpipe.

So you were having "problems" and further modified the car?

I'm still waiting for that log, but be aware that Catless DP concerns me. It won't cause an issue at altitude, but as soon as you drive closer to sea-level you will have gasflow issues through that OEM wastegate and will likely see boost creep.
I am planning on switching to a catted downpipe here soon, but for now, I am going to stay at higher altitude where I am not having those boost creep issues with the catless downpipe nor any lag or weird feeling on this tune.

But yes, even with the low-boost issues before, I put on the exhaust to see if it would potentially help, but obviously, something is still going on, I am just trying to troubleshoot what that could be.
 

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Discussion Starter #14
Do a log in 3rd gear 3000 RPM through 6000 RPM (be safe please) and log the following and nothing more:
1. RPM
2. Load
3. Throttle Position
4. Boost (manifold relative pressure)
5. Boost Target
6. TD Boost Error

Post the resulting CSV file here.

Also, per XJman's post -- please be clear on which map you are running (91 or 93 octane).
Here is that datalog you requested, sorry about the delay. I had to attach it as a PDF because I can't attach csv files
 

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