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Stattama not building boost and I can't figure out why?

S

slimguns

New member
Hey guys. I recently installed a set of ported heads, ported LIM, LS7 lifters, Intense push rods, and 1.9 modded rockers. Since the time I put it back together the car (originally an L36) runs fine with the exception that the T67 won't build boost. At WOT I stay at 5-7 pounds vacuum. I hear the whine of the turbo starting/wanting to spool but nothing, it doesn't cross into boost. I checked my oil line and I am getting oil. I checks for exhaust leaks, nothing found/heard. Where do I start/go next?

Again, it worked before the swap, now no-go. Ideas?

Oh yeah, it worked days before when I took it off the car.
 


The boost controller is flowing from the vacuum block, arrow pointing away from vacuum block, line out to top port of wastegate.

Wastegate has vacuum line from block into the lower port, boost control into top port.

Yesterday I was off so I leak checked my intercooler piping again, found a loose pipe so I just retightened all clamps and tested again, no leaks. I then installed my BOV directly to my vac block. No leaks. Installed/wired a mechanical boost gauge (mechanical and MAP match within about 1#), AEM wideband, and a Aeroforce Interceptor. I'm really rich but I will tune that down the next couple days. No KR. Double checked my oil line and there is oil flow. Checked the turbo turbine and it spins freely with my light finger pressure. Checked wastegate again, and....here's where my question comes in. Is this normal? I'm referring to the tolerances in the below pics.

Top two have valve guide installed (notice the clearance between guide and plunger):




Next three are no valve guide.



You can see light through the area around the plunger when the light is shined through the exhaust outlet. When actuated by hand it is hard to press in and requires two thumbs. I was told it has a 9# spring but the most boost ever seen was just above 6#s.

I'm at a loss, what else can I check?
 
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I will do that tomorrow...

By some off chance, would having lost the D shape of the exhaust ports caused this? That is my next option/guess? The heads came off a running car though so I wouldn't understand why... Just spit balling at this time.
 


The next dumb me part...

So tonight I was driving home from work with my windows down and ta-da, I hear the BOV. From my understanding it only operates during a pressure spike right? That means turbo is boosting but no pressure to the manifold (based on my mechanical, MAP sensor, and butt Dyno not sensing it). I paid a little more attention and it felt like less timing to as I pressed throttle, engine ups RPM but speed stays with a steady slow incline. I will scan to verify it tomorrow mainly watching my timing, MAF, KR, and MAP sensors. But, what can cause that? Weird to me!
 
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So more research has taught me the light BOV noise I'm hearing is only the shift from low vacuum to high vacuum in the UIM before the piping as the vacuum lines are closer to the cylinders. Sorry, over zealous noob mistake. Back to square one, no boost. Exhaust will be removed tomorrow. I'm kind of hoping that's the issue for two reasons. First, I'm back in boost. Second, good excuse to upgrade to 3" pipe!
 
hmm im experiencing the same thing. i have a small exhaust leak but that never stoped me from building boost. went from 15 to 10 now nothing past 5. ive even fully opened my wg and still 5
 
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In no case should you ever struggle to make 0 vacuum. If you can floor it without making boost passed 4k rpms you better hope there is a winter coat stuck in your exhaust because there is nothing else that will stop the turbo from doing its thing if you dont have obvious exhaust leaks.
 
Major boost leak somewhere.
Charge pipes are first on the list to check. Then intake manifold gaskets, lim gaskets, then head gaskets.
There's also a small chance your valve springs could suck, but that's a long shot.
 
I can make only 5 psi when flooring it. I was thinking maybe the charge pipes but I will have to do a leak test. I'll just tighten everything up once it gets warmer out or I just won't floor it till I can check it out.
 
silver3 said:
I can make only 5 psi when flooring it. I was thinking maybe the charge pipes but I will have to do a leak test. I'll just tighten everything up once it gets warmer out or I just won't floor it till I can check it out.
Click to expand...

if you make positive pressure and dont have leaks its probably just a wastegate control issue.
 


I make boost and I know I have an exhaust leak but it never restricted me to only 5psi. Even with the BC opened all the way only 5 psi. How would I test the wg?
 
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