Re: running rich under boost

[PDQSHIP@aol.com]

In a message dated 95-10-05 16:13:30 EDT, you write:

>
>Can someone who understands these things make some suggestions?
>
>The car's an '88 5KCSTQ Avant.
>
>>>>>>>>>
>
>In the Bosch Fuel Injection book by Probst, he says that there
>is enrichment by boost.  The mechanism is the fuel pressure
>regulator.  This is a mechanism about 2" * 2" * 5"  mounted 
>on the block under the #3 spark plug.  Notice on turbo cars
>that there are vaccum (pressure!) lines running from the 
>manifold. 
Not with the 86-89 1/2 turbos, there is no pressure or alt compensation to
these FPR's

>The system control pressure increases with pressure
>to prevent leaning out.  If you disconnect this line you will
>then presumably lean out under boost.  Easy does it though, that
>tends to promote detonation.
>
The control pressure on the 86-89 1/2 cars has only two distinct modes, at
full cold it will reduce the control pressure for a rich mix at cold temps,
then increase the CP as the car warms......  And at normal operating temp you
will have a set control pressure of somewhere around 3.5 bar (2.5
cold)........   The only way to make the mixture run rich at WOT is, 1)
richen the mixture at idle, or 2) reduce control pressure while warm......
 The WOT puts the duty cycle of the Lambda circuit at a computer preset level
of 85%.....   My first suggestion on this car is to ck the idle duty cycle,
you should peg it at 42%DC.....  This will give you a slightly rich mixture
on cold start up......  Sounds to me that if you are getting rich under boost
with no O2 hook up, you are fine tho..........
>paul t-
>
>
>
.......   Someones been here b4

Scott