Please help! losing boost somewhere....?
Thread Starter
Evolving Member
Joined: Dec 2007
Posts: 216
Likes: 1
From: Mesa, Az
Please help! losing boost somewhere....?
Ok, just went from zero to hero with this build, and have got 1 concern that gives me headaches 24/7. Literally, I have a hard time sleepin bc of this
Ive done some random, easy checks, and research, and am just extremely confused. Its an 03. and here are my exact mods: Please, ANY HELP/SUGGESTIONS will be greatly appreciated.
-Cometic Headgasket
-ARP headstuds
-BC valve springs and titanium retainers
-Cosworth M2 grind camshafts
-NGK plugs
-Mynes tubular manifold (ported)
-Evo 9 turbo (ported)
-Megan O2 housing (ported)
-Maradyne 12" slimfan
-AMS 3" TBE with test pipe
-Injen intake, UICP, LICP kit
-XS Engineering 3" FMIC
-JDM MR DV
-AP solid front motor mount
-Hallman pro MBC set at 23 psi
-PTE 880 injectors
-AP fuel rail
-Walbro 255lph fuel pump
-All t-bolt clamps
And probably some other stuff, now heres the problem: Car has been tuned on dyno, and mbc set at 23.5 psi. At around 3600rpm full boost(23.5 psi) hits, holds pretty well for a couple K rpm and then gradually starts tapering down to 18.1 psi, and then holds for a short distance to redline. I understand that boost taper will occur, and is inevitable, but 5+ psi? Especially with all the port work, I was expecting it to hold better than 2 or so.... Whats going on? Please ppl help me out. Thought I was going to be set on dyno day, but ended up being dissapointed with my numbers.....
Thanks
Ive done some random, easy checks, and research, and am just extremely confused. Its an 03. and here are my exact mods: Please, ANY HELP/SUGGESTIONS will be greatly appreciated.-Cometic Headgasket
-ARP headstuds
-BC valve springs and titanium retainers
-Cosworth M2 grind camshafts
-NGK plugs
-Mynes tubular manifold (ported)
-Evo 9 turbo (ported)
-Megan O2 housing (ported)
-Maradyne 12" slimfan
-AMS 3" TBE with test pipe
-Injen intake, UICP, LICP kit
-XS Engineering 3" FMIC
-JDM MR DV
-AP solid front motor mount
-Hallman pro MBC set at 23 psi
-PTE 880 injectors
-AP fuel rail
-Walbro 255lph fuel pump
-All t-bolt clamps
And probably some other stuff, now heres the problem: Car has been tuned on dyno, and mbc set at 23.5 psi. At around 3600rpm full boost(23.5 psi) hits, holds pretty well for a couple K rpm and then gradually starts tapering down to 18.1 psi, and then holds for a short distance to redline. I understand that boost taper will occur, and is inevitable, but 5+ psi? Especially with all the port work, I was expecting it to hold better than 2 or so.... Whats going on? Please ppl help me out. Thought I was going to be set on dyno day, but ended up being dissapointed with my numbers.....
Thanks
Last edited by IDRNKV8; Apr 16, 2008 at 07:01 PM. Reason: forgot some stuff!
Thread Starter
Evolving Member
Joined: Dec 2007
Posts: 216
Likes: 1
From: Mesa, Az
ported mani, turbo and o2, and no havent tried different one, u think that mbc isnt bleeding off enough? Ive heard anything over 21-22 psi, u should get an ebc......is that true?
Evolving Member
Joined: Jul 2005
Posts: 294
Likes: 0
From: Norfolk, VA
Obviously, I assume you already tried a boost leak test. When I had a similar issue to what you are describing, I found through a boost leak test that my Throttle body seals were shot and leaking horribly. This may or may not be the issue, but you can see here that many people are having the same issue:
https://www.evolutionm.net/forums/sh...tle+body+seals
https://www.evolutionm.net/forums/sh...tle+body+seals
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