on an 87' GN what was the psi on a stock motor?
For fuel pressure? Boost? Compression?
I'm sorry stock psi for Boost. I have a bone stock GN with 50k on the odometer that I just got and am in the proses of fixing up. the stock boost gauge only goes to 15psi but when under high load/acceleration it would peg out the stock gauge and pinging so I hooked up a manual gauge and it was hitting 18psi !?!
Stock boost should be around 15 psi. There are a lot of things that may cause it go higher. (Better exhaust, catalytic converter removed, control hose assembly leak, leaking wastegate actuator, etc.) If yours is higher due to a problem, you'll have to chase it down and correct it. If its due to reduced backpressure, you may need to add an adjustable wastegate or modify yours in order to bring the boost down to a tollerable level on pump gas.
thanks Scott. coming out of the wastegate I have a vacuum line that goes to a modal on top of the passenger side valve cover. the modal is black with a red clip and two wires coming out of it. what is this modal and why is one of the vacuum ports on it open?
That is the wastegate solenoid which sets the boost level upon instruction by the ecm. The open port is the bleed. When the solenoid opens, pressure in the line is bled off thru the solenoid via this open port.
Ok good. which of the two ports should be open, and these vacuum lines leaking could be the source of my over boosting?
It does not make any difference which port is open...
If you have cracked or loose hoses anywhere in the "Y" arrangement, you will have overboost.
So if nothing is leaking and my overboosting is form something else, couldn't I just put in a boost controller and bring the boost back down?