downpipe and boost SPIKE - Page 2 - Subaru WRX Forum
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#16 Old 07-26-2007, 12:57 AM
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Originally Posted by Imprezd02 View Post
Im having the same problem i have a dp and axle back and im spiking to 1.09kpa or 15.8psi if i even converted that correctly. Anything you can do to stop it without EM. Im broke for awhile
Not really. You could look into the open source tuning. Do a search for Enginuity.

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#17 Old 07-26-2007, 08:41 PM
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Is your DP catted? Im not sure if this is true with the MY06 as it is with the MY07, but read anyway. http://www.cobbforums.com/forums/ima...tIssues100.pdf
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#18 Old 07-26-2007, 09:25 PM
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just get some sort of EM and it will fix all the problems you are haveing

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#19 Old 07-27-2007, 07:10 AM
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Originally Posted by rss3781 View Post
Never herd that befor
Thats pretty obvious since you slapped a DP on an 06 without em and are now suprised of the results... The problem with the 06-07 is different than the 04-05's though.Big motor with tiny turbo.The wastegate is just too small.This is the same problem the VF39 STi's have when you mod them,boost creep.The 06-07 WRX's are tuned for 11.5 psi from the factory so that is a pretty bad spike.

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#20 Old 07-27-2007, 12:53 PM
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dyno tune and reflash done WOW

Dyno 18psi 282hp intake dp spt muffler. The reflash took care of all my problems and the car runs great
Thank you for the help
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#21 Old 07-27-2007, 09:05 PM
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Originally Posted by lucky4586 View Post
12 afr isnt bad at all if you go over 14.7 then you running way to lean but 12 is still a little rich must tuners tune for 12.5-13 at wot. But boost spike is always something you want to stay away from.


14.7 is for NA cars. most tuners will advise 11.5 afr is the leanest you run at WOT and full boost...

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I defected to an evo :)
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#22 Old 07-28-2007, 06:50 AM
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Originally Posted by lucky4586 View Post
12 afr isnt bad at all if you go over 14.7 then you running way to lean but 12 is still a little rich must tuners tune for 12.5-13 at wot. But boost spike is always something you want to stay away from.
14.7 is the targeted AFR in closed loop-low load.I actually target 15.2:1.Saves alittle gas and my EGT's are slightly higher=faster spool.13:1 and 12.5:1 are WOT afr's for N/A motors.Cobb's maps and some other tuners target down to 10.5:1-10:1@ WOT depending on boost levels.

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#23 Old 08-07-2007, 05:09 PM
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at what psi does the ecu cut fuel? with after market EM will you car still cut fuel?
ie. if im hitting 10psi stock and maybe the car peaks at 11/11.5 and then i get EM and a custom tune for 17psi will it still cut my fuel at like 18psi? boost usually stays in one general area but every now and then it will jump + or - like 2psi. that would suck if you tune was so close to the stock cut off that every time you hit WOT your car cut off on you
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#24 Old 08-08-2007, 01:19 PM
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Most EM will raise the fuel/boost cut and rpm limiter.

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#25 Old 08-08-2007, 01:30 PM
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Good Posting Dum Dum And Kjot21. Exhaust No Em Is Not Efficient, But Can Be Run, Not Recomended Though. And All These People Have Been Talkin About 18 Psi On Their Stock Wrx Turbo How Why What!!!!!!! Thats Not Right Even If You Are "tuned" Thats Out Of Its Efficiency Range.
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#26 Old 08-08-2007, 02:29 PM
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Cobb accessport stage 2. Problem solved.
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#27 Old 08-09-2007, 05:29 AM
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Originally Posted by drs View Post
And All These People Have Been Talkin About 18 Psi On Their Stock Wrx Turbo How Why What!!!!!!! Thats Not Right Even If You Are "tuned" Thats Out Of Its Efficiency Range.
I run 20psi in the midrange and taper to 14-15psi by redline.It's all about learning to read a compressor map
http://www.wallpaperinstaller.com/scooby/13T.jpg

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#28 Old 08-09-2007, 06:19 PM
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Quote:
The problem with the 06-07 is different than the 04-05's though.Big motor with tiny turbo.The wastegate is just too small.
I was having the same issue with my 07. I had the helix bellmouth DP w/o cat, traded for the divorced wastegate DP w/o cat and that solved my problem, for the time being, until more money roles in
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#29 Old 08-11-2007, 03:00 PM
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Originally Posted by lovemy07 View Post
I was having the same issue with my 07. I had the helix bellmouth DP w/o cat, traded for the divorced wastegate DP w/o cat and that solved my problem, for the time being, until more money roles in
The only way that would be helping your problem is that the new DP is more restrictive than the one you had.

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#30 Old 08-15-2007, 10:47 AM
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I've heard of this happening a lot with the EJ25 and although a reflash or stand-alone is the best way to go, there is a poor man's fix...allegedly. Bore out your wastegate passage. I don't know anyone who's tried it, but jscspeed.com says it works:

"04-06 STi OWNERS READ: On the 04-06 STi there are boost spike or creep issues in all cases with the use of an aftermarket downpipe or turboback that uses a bellmouth or external dump tube design. This is because the 2.5L engine pushes so much air. Even with the internal wastegate fully open not enough air can exit to stop spinning the turbo, the result is boost creep or boost spike. You can fix the problem by porting the stock turbo's wastegate passage (any exhaust shop should be able to do this or it can be done at home) or you can get an engine management system to fix the issue, like a UTEC or AccessPORT."

Hope this helps.
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