Date: Fri, 14 Aug 1998 09:59:53 -0700
Reply-To: "Beutler, Art (AZ75)" <Art.Beutler@CAS.HONEYWELL.COM>
Sender: Vanagon Mailing List <Vanagon@vanagon.com>
From: "Beutler, Art (AZ75)" <Art.Beutler@CAS.HONEYWELL.COM>
Subject: A long strange ECU story ...
Content-Type: text/plain
I have recently had more than a lifetimes worth of ECU (aka brain or
computer) trouble on my '86 Westy Woflsburg.
It started about 2 months ago; I had just loaded up my bass, amplifier, and
speakers in the early AM, given our singer's car a jump start, and went on
my way. About 5-10 miles down the road the van stopped dead and could not
be restarted. I called AAA (for the first of many times!) and was
eventually towed home.
The diagnoses from the workshop was that the injectors were running wide
open and this could only be the computer. Sure enough, when a junkyard
computer was procured the van was restored to running condition after
dealing with the effects of flooding the engine with fuel.
So, off I went and drove the van for about 6 weeks including an epic trip to
Northern Arizona. One very hot day (I live in Phoenix) it stopped running
just as I was heading north. Back into the shop - ignition this time. Shop
found corrosion at hall effect sensor connector; cleaned this up and van
appeared to be ok. However a couple of flame outs later combined with the
discovery that if I unplugged the hall effect sender and plugged it back in
I could get going again we decided that there must still be some corrosion
and to replace sender and connector. Back into the shop to have that work
done afterwards I went to pick up van - it quit before I left the shop.
Ignition timing and dwell were found to be widely varying (this with brand
new hall sensor) sometimes enough to cause the engine to stop. Since on the
(now infamous) Digifant system the timing is controlled by the ECU; it was
time to get yet another ECU.
It took about two weeks to get a replacement ECU at which point two arrived
(the long backordered one from VOA and the very recently ordered rebuilt
from Parts Place) on the same day! The brand new one was installed and (so
far) the van is running fine. (Thanks to Parts Place for shipping the Bosch
rebuilt unit so quickly! Unfortunately (for them) I must send it back;
since the shipping box remains unopened it obviously has not been installed)
Several questions (of course!) arise from this saga:
1) There seem to be roughly 3 revisions of the computer extant; the VW
part numbers end in 022(no suffix), 022A and 022D. The new computer is an
022D; are there any known improvements (such as enhanced reliability)
incorporated?
2) Although I doubt that I had my engine running when I jump started
our singer's car and the computer waited awhile to die, my mechanic believes
that this probably killed it. Those of us in the electrical engineering
community are skeptical since there was at least one (and sometimes) two
batteries in the circuit which should have minimized and voltage transients.
Does anyone have experience with ECU failure associated with some sort of
electrical transient?
3) I have the ECU from the junkyard in my possession. While waiting
for its replacement we disassembled it and reflowed several suspect solder
connections without effect (good or bad). This unit had been clearly worked
on using the "shotgun" approach to troubleshooting. Having an ECU core in
my possession and a general belief that the problem is associated with the
hall effect interface I am tempted to try to troubleshoot it but I need a
schematic. Is anyone out there fortunate enough to be in possession of such
a thing?
4) Any comments on the association between the initial diagnoses of
hall effect sensor connector trouble (complete with observation that
unplugging and reconnecting it clears the dead van problem) and the eventual
finding? Again, a computer schematic would be of help in understanding this
since unless both computer and connection were dead there must be some sort
of retained charge phenomena in the computer.
Art Beutler
