Strange problem. Running single turbo setup, I did 1-3 gear run the other day and noticed that the PFC read .74mmhg. I shifted at 6200rpms. Well I was informed that the PFC readings are lower then actual boost attained. So I figure I got up to at least 11 psi probably 12 0r even 13 psi. Weird thing is that I'm running the Profec B spec II turned which is turned off until tuning session. I'm also running the HKS standard 40mm wastegate with Blue spring 9.7 psi. I have the top nipple on the wastegate connected to COM on boost controller and side nipple on wastegate connected to manifold pressure after throttle body. I'm wondering why I over boosted? I always thought that if you have the boost controller off your boost would not exceed the wastegate spring. At least in previous experiences. I checked all the lines and they are snug. I have to admit it was the first time I got to 6200 rpms since the new motor and it was fun. I broke the rear wheels loose and started going sideways. Any input would be greatly appreciated. Thanks..!!

 

(1) 74mmhg is vacuum, so how did you overboost?
(2) the top fitting on the WG goes to the controlled output of the WG solenoid.
(3) the side fitting on the WG should go to a "T" which attaches to the pressure output of the turbo before the throttle body and to the input of the WG solenoid.
Make sure you boost controller is also set to external WG.

Read you boost controller manual carefully!

 

(1) Yes, are you sure you didn't underboost? I suppose you meant 0.74 kg/cm^2. It is certainly possible to get some spiking (or even creep) over what your WG spring pressure is. I bet you got spiking since the boost signal on your setup is taken after the throttle. Take the signal from the compressor outlet -- that might remedy the problem (if it is really a problem -- it might not be).

(2) "COM" is the COMmon port on the solenoid, so it sounds like this is hooked up right. The NO port on the solenoid should be open/vented/nothing-attached, and the NC port should be connected to a boost source (compressor outlet).

-Max

 

Thanks for the help so far guys. I actually called up Greddy and they told me I could hook up the NC to the upper manifold (vacuum source). Reason is I don't have any were to tap into the compressor on the turbo. I was going to go ahead and attach a barbed nipple on my intercooler pipe right after the compressor, but the Greddy tech insisted that tapping into a vacuum source after the throttle body would work just as well. Hmmm...Ok so I multiply .74Kgl/cm^2 x 14.223=10.52psi. Well I guess I didn't overboost that much then.