It's a 3-port valve that has one port open when the other is closed, so open-vs-closed is just a matter of point of view. In one position the WG can is connected to boost pressure and in the other it is vented to atmosphere. If your turbo's efficiency curve is mismatched to the engine's efficiency curve, or if your exhaust generates too much backpressure, boost may be limited in certain rpm/power ranges but not others. Exhaust backpressure can vary with rpm as well as flow volume because of resonance(s) in the pipe. If the WG port is too small or is routed improperly boost can also become uncontrollably high in certain rpm/power ranges.
----- Original Message ----- From: "Rob Ebersol" <[EMAIL PROTECTED]> To: "Ray Ayala" <[EMAIL PROTECTED]> Cc: "miatapwrlist List" <[email protected]> Sent: Saturday, June 14, 2008 8:05 AM Subject: Re: boost solenoid max duty > It's my understanding that a WG% 98 means that the valve is shut (nearly) > all the time since it's normally open w/o a signal/trigger. > > In open loop at a WG% of 82 from 4k on I see ~15psi. At a WG% of 78 in > open loop I was seeing ~13psi. That leads me to believe that the > decreasing duty means you are decreasing how frequently/long the valve is > shut. IOW a value of 40 means the actuator has more exposure to boost > level equaling less boost, and a value of 60 means less exposure to boost > level generating more boost. > > So if the WG% are equal both in closed and open loop, I would expect a > closed loop WG% value of 98 far more than 18psi peak, when an open loop > WG% 85 made 15psi+. > > Could that be indicative that there is restriction in the exhaust? > > I suppose I could set open loop values to 98 and see if I indeed get the > ~18psi result. > > On Jun 13, 2008, at 8:15 PM, Ray Ayala wrote: > >> At 98% the valve never closes at all. The reason for staying at 98% >> instead >> of 100% is so that the valve doesn't stick open so long when you *want* >> it >> to close again. > _______________________________________________ Miatapower mailing list [email protected] http://list.miatapower.net/cgi-bin/mailman/listinfo/miatapower
