Date:         Thu, 29 Jan 2004 09:40:19 -0800
Reply-To:     Damon Campbell <damoncampbellvw@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Damon Campbell <damoncampbellvw@YAHOO.COM>
Subject:      Weird bucking
Content-Type: text/plain; charset=us-ascii

In the last couple months, i've had a noticeable
low-speed driveability problem... kind of a
herky-jerky bucking at very light throttles.  Happens
in any gear, but is more pronounced the lower a gear
you are in (1st being worst, 4th being not too bad).
This typically happens around 1500-2200 rpm, and kind
of comes and goes during a drive through town.

I've had my trusty digitool on the dash looking for
any correlation, and there is nothing i can see from
any of the readouts.  O2 is stable, AFM doesn't really
change at all, temp sensors doing their thing
normally... the only thing maybe kind of weird is that
i typically show a .06v ground potential difference
(since i have a digijet, my pin 19 is apparently a
ground reference, or something like that).  This .06v
is always there, though, buck or not.  This has
happened with two different ECUs, too.

Now, i'm wondering if it could be possible that a
rebuilt tranny with clearances a little loose, a
specific clutch spring stiffness (actually have that
uber-LUK clutch bus-depot sells), a bigger motor, etc.
could all conspire to give a natural frequency at low
loads and certain rpms?  This bucking, once it starts,
can be attenuated by either putting in the clutch, or
giving it a bit of gas...  If the load and rpm are
just right, the bucking can build up to be quite
violent.

How likely is this scenario?  And if not, what would
some alternate theories be?  The main two variables
include big engine and new clutch (had same rebuilt
tranny before new engine).

As always, I appreciate all your thoughts on this,
-Damon

=====
'84 Westy (Sparky) w/2.3L WBX (wow... it actually works!)

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