Boost Controllers

[Dwayne Cosby <dccosby@interlog.com>]

>>> 
Prior to the Profec, it would pull 11psig in first and second gears
and 13 psig in the higher gears. The boost would fall off to 11 psig
sustained in the higher gears.  Throttle response was good and there were
no perceptible timing or fuel problems. 

The Profec was installed to 1)allow higher boost levels, 2)eliminate the
boost fall-off, which I thought was due to the stock WGFV. Well, I can
dial in more boost, but the boost profile is far from what I expected. 

First of all, with the Profec connected (and the stock WGFV eliminated),
but with its power OFF, I now get 12psig in first and second gears, 14psig
in third and fourth gears, and 15psig in fifth gear. The boost falls off a
bit (~ 2psig) in the higher gears just as before. 
<<<


Your post makes me think that you have the Greddy plumbing hooked up
incorrectly. You found that you can get 15psi of boost in 5th gear with
the Profec OFF (versus 13 psi before the Profec was installed). When the
unit is off, boost should be controlled only by the wastegate spring.
Since you were only getting 13psi before the controller, the spring must
be rated below 13 psi (as the stock setup only adds pressure to keep the
wastegate closed). Getting 15+psi with the controller off, implies to me
that manifold pressure is somehow being applied to wastegate to keep it
closed. This could either be due to the plumbing being installed
incorrectly, or the solenoid is leaking. 

I can't comment on setting up the Profec, but I don't think that's the
source of your problems.

I run a Apex'i controller in conjunction with and IA chip on my 94 S4. I
still run the same peak boost as with the chip alone. With the controller,
all lag is gone, the car is much more responsive, has more boost sooner,
and midrange power is greatly increased. The car has gone from quick to
scary fast. The best $400 I could have spent. For those doubters, have a
look at the following link for before and after results (HP and 0-60
times) running a controller at the *same* peak boost. 

	http://www.msu.edu/~jenkinsg/evcretns.html

Good luck,
Dwayne Cosby
94 S4