Hey guys.

My setup:

D16Z6
T25 Turbo - INternally Gated (Only has 1500kms on it)
2.5" DP down to 2.5" exhaust all the way back.
Uberdata Tuned

The problem:

#1. At idle when im just sitting around I get about 12in/hg of vacuum. If I rev the motor and let off, the vacuum goes to 8-10 and the motor stumbles.

#2. I cannot boost past 8PSI with an MBC. I took the MBC and put turned it to have about 20PSI and it dosnt change a thing. I get about 5PSi by 3000 and 8psi by 3800 then by 4400 I'm down to 5 psi all the way to redline. (Another thing, if im on the highway, i can hold 8-9PSI all the way to redline.

#3. With no MBC I can make and hold 4PSI all the way to redline.

What I've tried:

I replaced ALL my vacuum lines. Every single one. - Didnt help
Installed a vacuum log and ran seperate lines off of it to each source needed - Didnt help
Checked and double checked all my IC piping with fitting and air compressor (to hear/feel for leaks) - Nothing.
Tried 2 seperate boost guages to check for inconsistency - Nothin

Does anyone have ANY feedback on this? I dont know where else I could have such a bad vacuum/boost leak and its really starting to drive me nuts .

The only other thing I can think of is: Long ago I pulled the IM off the car but never replaced the gasket and resused the old one. Could that be it?




Edit: Compression test yeilds 200psi across the boards (Rings were replaced about 4000km ago and new HG was installed)

 

Dude, your not holding boost for one reason. BOOST LEAK..!

Same situation with me. I just tossed all my gaskets away from Manifold--->Turbo--> to downpipe... and just used my stock headgasket for the head..

Now boost holds consistant, compared to loss of boost etc...

FIX your boost leak first! Then worry with the Vac after that, since its easier to work with your MBC afterwards, since you know that the boost is at MAX usuage...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by synik &raquo;</TD></TR><TR><TD CLASS="quote">Dude, your not holding boost for one reason. BOOST LEAK..!

Same situation with me. I just tossed all my gaskets away from Manifold---&gt;Turbo--&gt; to downpipe... and just used my stock headgasket for the head..

Now boost holds consistant, compared to loss of boost etc...

FIX your boost leak first! Then worry with the Vac after that, since its easier to work with your MBC afterwards, since you know that the boost is at MAX usuage...</TD></TR></TABLE>

So what should I do? The gasket from the head tot he exhaust mani = brand new. The gasket from the turbo to the turbo mani is also brand new. Im not running a gasket between my Turbo and O2/DP as it shouldnt affect boost plus its not leaking.

Where else am I leaking? Intake manifold gasket?

 

was the turbo new and its internal right, maybe a crack inbetween the down pipe and the wastegatein side. as for the vacum at idle unless u have a massive leak on ur intake manifold or behind ur tb i see no reason to have such vacum. So hit me up.

 

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

So what should I do? The gasket from the head tot he exhaust mani = brand new. The gasket from the turbo to the turbo mani is also brand new. Im not running a gasket between my Turbo and O2/DP as it shouldnt affect boost plus its not leaking.

Where else am I leaking? Intake manifold gasket?</TD></TR></TABLE>

Is the Turbo and manifold new? If so, the flanges should be milled flat already. I would just recommend running no gasket from the manifold to turbo... So next time you have a leak somewhere, you will know its not there, since theres no gasket. Just one elimination out of the factor.

 

if your vacuum is that bad at idle then you definantely have a good vacuum leak. This is also effecting your boost. I would try replacing that intake manifold gasket if you've already replaced all the vacuum lines.

 

how's your timing?

 

help this guy

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98lude-t &raquo;</TD></TR><TR><TD CLASS="quote">was the turbo new and its internal right, maybe a crack inbetween the down pipe and the wastegatein side. as for the vacum at idle unless u have a massive leak on ur intake manifold or behind ur tb i see no reason to have such vacum. So hit me up.</TD></TR></TABLE>

How would an exhaust leak from the turbo to the DP affect low vacuum and less boost? Just a question as im not sure. Though I'm positive that its not leaky there.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by synik &raquo;</TD></TR><TR><TD CLASS="quote">if your vacuum is that bad at idle then you definantely have a good vacuum leak. This is also effecting your boost. I would try replacing that intake manifold gasket if you've already replaced all the vacuum lines.
</TD></TR></TABLE>

I'm going to go buy the gasket from Honda tommorow morning and replace it. Does anoyne know what the ballpark price is for one of those?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by StrokedPSI &raquo;</TD></TR><TR><TD CLASS="quote">how's your timing? </TD></TR></TABLE>

I believe its fine. I havnt checked it with a timing light though timing was set after i pulled the head and made sure everything lined up properly.

 

replace the intake manifold gasket yet?

 

Make a leak tester and pressurize your whole system.

Go buy a radiator hose that fits over the intake of the turbo, a pvc cap and a valve stem. Presurize the system with a air compressor, any leaks will be evident.

 

how do you know if you have hooked up the MBC correctly? how do you know its set for 20 psi?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sbiggi &raquo;</TD></TR><TR><TD CLASS="quote">Make a leak tester and pressurize your whole system.

Go buy a radiator hose that fits over the intake of the turbo, a pvc cap and a valve stem. Presurize the system with a air compressor, any leaks will be evident.</TD></TR></TABLE>

he's already done this... said so in his first post.