Thread: not building boost anymore?

currently running a Z7 kit with ~25k miles. im running the stattama MBC and have a 11lb spring in the 38mm Tial WG. currently i realize it wont go above 16psi after 4 turns on my MBC. before i can easily run 20psi. any suggestions? something went bad in the WG or MBC or something totally different? my IAC at idle with warm motor is 71-72cts and my electric boost guage reads ~-21inHg.

you never know lol

Originally Posted by darkhorizon

if cgp cant help... gpf turbo section is not going to do much more than suggest you are running too small of a pulley.

why do we have to be dumb? notice how no one answered for the fact that they just straight up dont know? not everyone has a turbo setup, nor cares to have one.

have you checked for a cracked vaccum line to your wastegate?

with 25k miles on the setup you should be checking all that minor stuff anyway

have you checked for a cracked vaccum line to your wastegate?

with 25k miles on the setup you should be checking all that minor stuff anyway
02-18-2011 05:24 PM

yea i'll double check. i would imagine if it was cracked my boost gauge would be reading closer to 0 inHg but its hovering around -22inHg. here's another thing i checked, i used a vacuum pump and checked the pressure on both top and bottom ports of the WG. the top port holds pressure fine but when i add air into the bottom port it only goes up to 2psi then drops back to zero slowly. i dont know if thats suppose to happen.

i would say with that kind of miles on the set up just run down to the parts store and get some new lines and replace it all

after many bad experiences in the past.. i started using fuel line to do my vaccum lines instead of the floppy sh!t you get from kragen called vaccum lines


got any pics of your vaccum line set up?

I am using fuel line rubber hoses as my vac lines ;-)
no pics but i can tell you how everything's routed:
-on the m90 casing i have the one closest to the front "T" where one goes to the bottom port of the WG and the other end going to the BOV

-from the FPR goes to a "T" at the LIM and the other end goes to another "T" where it goes to the MAP and the other end goes through the firewall where it splits to another "T" one to my boost gauge and the other to the MBC

hmmm.... i personally have always ran a T from the line going to the fpr to the wastegate also, and ran the boost gauge from a seperate spot, maybe its different on these cars... i cant really speak with any knowledge on the vaccum locations with the supercharger, but just as a preference of mine i like the fpr and wastegate seeing the exact same pressure

i honestly never had a problem running how i have it now until recently.

yeah i figured you didnt, thats why the instant suspect was just wear and tear

check em out and let us know =)

i'll try but i doubt it'll do anything....just paraphrasing my vacuum via electrical boost gauge reads -22inHg when warmed up. even my IAC is 132cts via LS1M.

just a late update:
i found the problem and it turned out my silicone coupler in between the TB and LS1 MAF there was a small tear when i tightened the t-clamp that slips over the LS1 MAF. did a leak test and heard it hissing in that area.

however i just found out the other day i have an exhaust leak on the turbo crossover. the weld separated where the one pipe comes off the crossover that connects to the turbo. sucks and i gotta tear the turbo, TB, turbo downpipe and WG out to get to the turbo crossover. here's hoping i dont break any bolts/studs in the process :-\

Damn that sucks! Hopefully you will have it back up and running by next week.