car wont boost over 16psi with MBC all the way tightened

suprafanatic

New Member
May 25, 2007
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Greenwood, IN
i had a cheap manual boost controller and with it tighted all the way it would only boost to 16psi, so i got a new turbonetics type MBC and the car still only boosts to 16psi even with it all the way tightened.. so i disconnected the MBC and just plugged up the boost line so it should be boosting crazy high, but still only hit 16 psi... any ideas why it wont boost any higher? would this be a boost leak or somthing else? im not hitting fuel cut at all.. i have a 60-1 CT turbo, 255walbro, 550s/lex, safc II, wideband, 3in exhaust, full hard pipe kit and speacro replica intercooler.
 

suprafanatic

New Member
May 25, 2007
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Greenwood, IN
oh, ok.. i will try that... i'v always wondered if it were possible for the flapper to open like that on its own. i'll give it a shot tomorow morning and see what happens. thanks IJ.
 

IJ.

Grumpy Old Man
Mar 30, 2005
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I come from a land down under
It's a limitation of the Internal gate design, they run a light spring to open at stock boost and over the years the spring sags.

You wind the boost up and the leverage on the arm is enough to blow the gate open.

My old 3540R suffered from this when I tried to run a 7 psi actuator and cranked the controller up.
 

supraguy@aol

Well-Known Member
Dec 30, 2005
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Atlanta
If that doesn't work, I have a question- when you boost up, does it take awhile to get to 16psi? I had the same problem, where i had set my MBC to 12 psi, and it started slowly coming down to a max of 9psi, and it took longer and longer to spool up. I found out that my cat was WAY clogged, and was only a year old. I replaced it and almost shat myself when the boost hit so quickly.