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Re: WG control (was fooling compooter and other things)
> Frank J. Bauer
> dassault systemes of America email:email@example.com
> Subject: WG control (was fooling compooter and other things)
> PDQscott sez:
> >A better mod on the later cars would be to address the programming
> >of the DC in the WG solenoid circuit...
> then SHRAPpaul sez:
> >Or eliminate the WGFV from the system altogether.
> then STEDIric sez:
> >At that point you have no computer control of the wastegate......
> that's why it's called the shrapnel knobben - that clockwise twist
> is controlled by the ratio of balls - to - brains! =8)
> at which point i remind everybody (except SKP, who obviously remembers)
> that no pre-MC motors have computer control of the wastegate.
> >Addressing the Programming of the WGFV and changing the way how it
> >controls boost is the hot ticket...
> just not an accessible mod to the starving student who asked the question
> in the first place - or most of us who aren't sending $$$$ to olympia
I just got in from testing the latest EPROM that I burnt... one which attempts
to control the WG solenoid to obtain approx 1.8bar. This time I seem
to be successful. What is the cost of this? $7 for the EPROM and $1
for the socket. Add another $15 for the desoldering iron and solder
from Rat Shack and there you have the low $$ solution.
Of course, you are risking destroying a $$$ computer when you unsolder the
EPROM... I wouldn't risk it on anyone else's computer myself.
I also don't recommend fooling the computer into keeping the fuel pump
on by the zener diode mod or by grounding the fuel pump wire from the
computer. It is $$$$ to fix your engine...
I have also used a pressure regulator to control boost ($15 for the regulator
and $5 for fittings). Again though, I modified the EPROM to cut fuel
at 1.95bar. This SAVED MY ENGINE several times when my wastegate
diaphragm ripped - and yours will too if your car is 10 years old and
you increase the boost.
Using the pressure regulator has a couple of benefits over the EPROM
only and one major drawback.
Benefits are the fact that the boost can be varied by turning the knob
and that boost will build up at part throttle, making the car somewhat
The drawback is that the only recourse the computer has to overboost
or knocking is to kill the fuel pump.
With the EPROM only solution, the wastegate solenoid is only activated at
WOT and the timing isn't at maximum retard due to knocking and the
engine is warm enough etc.. The engine is a lot safer! It also makes
the car a little easier to drive at freeway speeds since the 'real
boost' doesn't come on until you hit about 2/3 throttle.
So, what's the point? Use the Schrapnel Knobben or pressure regulator
or spring to increase boost, but DO NOT defeat the fuel pump cutoff
whatever you do!