civic_jdm

Ive checked charge pipes and seems all good. Its a D16Z6 with 15g greddy kit with trust front mount and running uberdata. I have a problem of boost ...It goes to 12 and then drops to 9ish and then back up and back down.. Surges between 12ish and 9.5ish prolly .
Question is is it my exhaust? Ive heard that could cuz boost to drop after it peaks. Im running a decently sized resonator and a 50 series flowmaster on 2 1/4 inch exhaust, Is this enough to make it drop that much? Could it be the turbo exhaust housing being cracked? Turbo ran fine on car before mine and pulled it the day it ran fine and threw it on mine but he had 3 inch greddy exhaust... Any other ideas???

CRXdan

Are you using amnual boost controller of some kind?
Where is your wastegate actuator signal coming from?

civic_jdm

i am using a boost controller, tried 2 different ones with same results. Line comes off turbo housing straight to wastegate actuator. Could it be the wastegate? Like maybe it got bumped on install or removeal of motor??? Starting to boggle me

js96ek

I think it might be the waste gate assuming you dont have a boost controller

TURBO DC2

what could be happening is its hitting the wastegate spring hard, then it dumps which causes it to drop in psi. Then another surge hits the wastegate and this happens again. I would suggest maybe messing with the boost controller and try to have it hold at around 7 psi cuz obviously its bouncing back and forth and the wastegate is seeing 9 psi and not holding it.


Modified by slammed_gsr at 6:43 AM 5/18/2005

1boostedcivic

i have the same problem on my coupe. but around that area. I fixed it with closing the gaps on my spark splugs to .28

SPOOLED

Change the boost source to the wastegate from the turbo to the manifold, I had the same problem then I moved my wastegate boost source to the manifold and problem was solved!

civic_jdm

i love how people dont read the whole story. YES I HAVE A MANUAL BOOST CONTROLLER AND IVE TRIED 2 DIFFERENT ONES

99_Ek9

I would also like to know the answer to this question. I have a boost surge from 12psi to 10psi and back to 12psi, but I am using a HKS AVC EBC that is installed according to the directions that came with EBC.

91integraLSVTEC

i also have the same problem with my 15g greddy kit. recently installed a boost gauge and i noticed that it will build boost to 7psi and then as the rpms increase it would drop to 5psi. ????? i dont know

PrettyLude

make sure the actuator has its own vacuum source and not teed into a whole bunch of other sources, i bet that might solve the problem

nerdsports

yea. according to my boost guage... i hit 10psi then drops to about 8.5-9. not that bad i guess.

usually happens if punch it at around 4K it'll build up 10psi then drop down some. if i punch it from 2K and let it go up, it wont do it.

Harassing Herbs

you could be losing boost from the overlap of your cams.
you will notice it a lil more if you have vtec.

set your vtec to 8rpm and see if you still have the same problem

Ls InTeGrA RaCeR

I have the same problem with my 18g Greddy Kit on my Teg.

civic_jdm

my wastegate actuator is coming off the turbo inlet vaccum port and is ran through a boost controller....Just wondering if my exhaust is really that restrictive since a greddy kit is made for 5.5psi and not 10+ psi??? Its a flowmaster and resonator but who knows???

91integraLSVTEC

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPOOLED &raquo;</TD></TR><TR><TD CLASS="quote">Change the boost source to the wastegate from the turbo to the manifold, I had the same problem then I moved my wastegate boost source to the manifold and problem was solved! </TD></TR></TABLE>


thanks for the tip, that solved my problem! holding 6psi to redline with that tip

1boostedcivic

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 91integraLSVTEC &raquo;</TD></TR><TR><TD CLASS="quote">


thanks for the tip, that solved my problem! holding 6psi to redline with that tip </TD></TR></TABLE>i gotta try this when i get home

Boosted2K1Civic17"

I believe that is how its supposed to be hooked up anyways. My directions said that for the profec-b, and it worked perfect (after I realized the jumpers were set incorrect, lol)

B16Civic93

yeah, i have the same problem with mine, its not as bad as it was after the profec b install, but i think its just because it spikes to like 9ish than drops down to around 7-7.5. however i have an 18g on a b16.

i have all of hte vacuum sources coming off the same line that goes to the fpr. thats the only source that comes off of my manifold, except from the brake booster. but if you think about it its no different than using a vacuum manifold.

EKhothatch

It could be due partly to an exhaust restriction. But you could use a EBC and turn the gain up.

SOHC_MShue

i have the same problem using a small wrx turbo and a tial 38mm wastegate. the vac source is tied to my brake booster. It boosts to 10psi like i want it and then drops back to 8.5psi. Even after upgrading to a 10psi spring it won't boost, but maybe .5psi higher.