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Old 03-14-2019, 07:36 PM   #1
Rutrosnax
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Member#: 354175
Join Date: Apr 2013
Location: Eastern ct
Vehicle:
04 Wrx wagon
Psm

Default Low engine vacuum at idle

Whats up guys so little issue, tired looking found a thread that came somewhat close but still looking for second opinions

2004 wrx built 2.0

When i was running my built block stock heads i had -18 to -20 for vacuum once i swapped my built remanned 2.0 heads with BC272 cams, titanium springs, 1mm over valves yada yada decked i went down to -9 to -11 for vacuum. Ive been dealing with it for like a year and a half now still cant figure it out. Compression checked and is 150 across the board, cant find a leak anywhere, redid the timing 3 times still the same, my original tuner kept saying there is an issue and wants me to tear it apart again. Before i do im looking to see if anyone has any other ideas?



My 04 wrx wagon build

Rallispec street spec 2.0l block
Mhale 8:5;1 forged pistons
Manley forged h beam rods
STI 11mm oil pump
OEM hardened crank
Gates racing timing belt and water pump kit
arp head studs, and all arp hardware in the block
STI killer b pickup and windage tray
STI oil pan
HKS equal length headers
Grimmspeed 44mm ewg uppipe with tial gate setup with a 1bar spring
Grimmspeed 3port ebcs
2.0 remanned built heads with bc272 cams, bc hardened valves, bc retainers, bc single titanium race springs
Perrin catted downpipe
HKS race exhaust
NGK 1step colder plugs
ACL race rod bearings
King main bearings
Mishimoto radiator
Perrin front mount coolant overflow res
Dw200 fuel pump
Injector dynamics 1000cc injectors
Blouch 20g-xtr ball bearing turbo with 10cm hotside with 3" inlet
3" turbo inlet
Moroso AOS
2002 jdm sti 6speed non dccd trans
2002 sti r180 diff
2002 sti flywheel
ACT extreme duty heavy duty 6puck clutch
2004 sti hubs
2004 sti axles
2004 sti brembos
2004 sti wheels
Innovate wideband
SPT shortram intake
Turbo xs front mount with a turbo xs 50/50 bov but am prolly going to do my hks ssqv at the time of tune
Aem iat sensor in the frontmount pipe
Cobb v2 acessport
Aem 3.5bar map sensor and adapter and pigtail

Any input could be very helpful
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Old 03-14-2019, 10:45 PM   #2
Rideit636
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Join Date: Feb 2011
Chapter/Region: NESIC
Location: Cape Cod, MA
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Edit, didn't see cams were added. Vacuum is still on the low side though.

Last edited by Rideit636; 03-15-2019 at 11:54 PM.
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Old 03-14-2019, 11:12 PM   #3
Rickyh
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Location: Metairie, Louisiana
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you are going to have less vacuum with larger cams. there is nothing wrong. I had 272 cams and my numbers were similar to yours.
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Old 03-15-2019, 01:14 AM   #4
Rutrosnax
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Location: Eastern ct
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Quote:
Originally Posted by Rideit636 View Post
I'd do a leakdown.
Ty sir yea thats the next thing ima do had the car 6 years drove it for maybe 2 haha 1 engine 4 transmissions and now she sits
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Old 03-15-2019, 01:16 AM   #5
Rutrosnax
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04 Wrx wagon
Psm

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Quote:
Originally Posted by Rickyh View Post
you are going to have less vacuum with larger cams. there is nothing wrong. I had 272 cams and my numbers were similar to yours.
I mean thats what i was figuring, the tuner i was using was saying he couldnt tune it that there was an issue cuz his built to the hill track car which has larger cams said his vacuum is -18 to -20 so somethings off im no longer using him not just cuz of that but yea.
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Old 03-15-2019, 06:16 AM   #6
rtv900
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Quote:
Originally Posted by Rickyh View Post
you are going to have less vacuum with larger cams. there is nothing wrong. I had 272 cams and my numbers were similar to yours.
^this
272 cams, less vacuum


Quote:
Originally Posted by Rutrosnax View Post
Ty sir yea thats the next thing ima do had the car 6 years drove it for maybe 2 haha 1 engine 4 transmissions and now she sits
^this sentence is awesome
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Old 03-15-2019, 12:03 PM   #7
subaru_gc8
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2004 WRX wagon
silver

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Quote:
Originally Posted by Rutrosnax View Post
I mean thats what i was figuring, the tuner i was using was saying he couldnt tune it that there was an issue cuz his built to the hill track car which has larger cams said his vacuum is -18 to -20 so somethings off im no longer using him not just cuz of that but yea.
time for a new tuner
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Old 03-15-2019, 02:12 PM   #8
Rutrosnax
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Location: Eastern ct
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04 Wrx wagon
Psm

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Quote:
Originally Posted by subaru_gc8 View Post
time for a new tuner
Yepp just talked with one of my old tuners for like an hour and he said the my new tuner is a idiot lol and said its about normal with the 272s
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Old 03-15-2019, 02:14 PM   #9
subaru_gc8
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Location: Orange County CA
Vehicle:
2004 WRX wagon
silver

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Quote:
Originally Posted by Rutrosnax View Post
Yepp just talked with one of my old tuners for like an hour and he said the my new tuner is a idiot lol and said its about normal with the 272s
Yeah some of the tuners out there are pretty scary tll
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