Holley 4D experiences

[Bruce Plecan]

-----Original Message-----
From: Mike Jones <rmjones at cyberhighway.net>
To: 'diy_efi at efi332.eng.ohio-state.edu' <diy_efi at efi332.eng.ohio-state.edu>
Date: Monday, May 04, 1998 1:35 PM
Subject: Holley 4D experiences

>Well, got my boat on the water for the first time with TBI and GT40P heads.
What a difference!  Instant starts cold and hot, terrific throttle
>response, much better acceleration and 3 mph increase in top speed (that's
a lot for a boat.)
>Just a couple of minor problems to work through.  One involves a too-high
idle speed when operating closed-loop.  Should be easily solveable.
>The second problem goes like this:  Running at full throttle produces 4000
rpms.  Backing down to 3800 rpms briefly, and then applying full throttle
brings up 4150-4200 rpms, which then decays over three-four seconds back to
4000 rpms.  The high speed jet control is nearly maxed out.  I'm going to
try increased fuel pressure next.
>
>Mounting the O2 sensor in the crossover passage seems to basically work
fine.  Acceleration, top speed and part-throttle cruise were all unchanged
or improved from open-loop (although that placement may be contributing to
the high closed-loop idle speed.  Something I have to look at yet.)
>
>Mike J.
>
Use anything ya got til the Wide Ratio O2 sensor is done, but like
a DVM, and see what ya got for WOT O2 voltage.  Doin plug cuts
onna boat never worked for me, since the prop always made the
motor spin down too slowly.  Ya might just use a dwell meter (like
for setting points [ya remember them, right?]), and hook that on the
ecm side of the injectors and make sure the ecm isn't reducing
the injector on time (the dwell would decrease if it is)..
  Did that sytyem have a MAP?.
      One other thought hook a vacuum guage to the manifold and see if after
a few minutes that it isn't generating a vac, at WOT, and
that isn't the problem.  Like the restrictor plate engines at continious
WOT.  TB, might be too small for continued WOT.
Bruce