I just got done hooking up a profec b on my bpu. I followed the directions on mkiv.com exactly and double checked it. When i drive the car and attempt to set the low boost the most i can get out of it is between 14-15. I thought that i was supposed to be able to go up to 20psi with ease? What's base boost?

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Originally posted by spooldup:
I just got done hooking up a profec b on my bpu. I followed the directions on mkiv.com exactly and double checked it. When i drive the car and attempt to set the low boost the most i can get out of it is between 14-15. I thought that i was supposed to be able to go up to 20psi with ease? What's base boost?

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You have it hooked up correctly, you will get max of 15psi on the twins on the low setting. If you want more boost, that is what the high adjustment knob if for. In the heat of summer, the twins will peak to about 20-21 psi then drop to 18 psi at red line on the max high setting. During the cooler months, the twins on the max high setting will spike as high 25 psi.

dont forget to also install a Greddy BCC (Boost Cut Controller) or HKS Fuel Cut Defenser

These unit's prevent fuel cut at Wide Open Throttle when your turbos want to make more boost than your onboard computers allows them to.

1994 mkiv w/sp63 single turbo
Technology is the only substitue for cubic inches...! (for now)

Had the sanme problem until yesterday.
Problem now solved. Turns out it was the waste gate spring. I went to Schucks and bought a kit of universal throttle return springs. The kind with straight ends, not hook ends. You cut and bend your own ends for your application. I used the stiffest one out of the package, bent small loops at both ends, then hooked one end around the flat lever/arm of the waste gate (next to the pivot point of the actuator). Then I stretched the spring and hooked the other end to the unused, threaded hole on the extra boss on the waterpunp. Now, With my ProfecB all the way up I can boost to 20 psi. I set high to a solid 18psi (at about the 3 o'clock position) When I turn the ProfecB off, I boost to 11-12 psi and it holds to redline. I can highly recommend this little mod to anyone who is having the boost drop problem. If you want pics, let me know.



___________
-Goldfinger

93 MSB Supra TwinTurbo BPU+
76 Porsche 911 RS <-for sale

please post a pic! Thanks for the help. I was going nuts over here.

That is correct... its def. your wastegate spring.. replace it and enjoy

___________
-Goldfinger

93 MSB Supra TwinTurbo BPU+
76 Porsche 911 RS <-for sale

OK, I dont know too much about cars but I want to do this to my supra. what do I need to get and how do I do it? Again I know little about cars but can learn fast.

low boost on the profec is 14psi and high boost goes to 28-29 psi. its working correctly.

Mike
MotorMatrix.com
R.A.W Racing
1.877.84.Motor
SFP.net

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