Date: Tue, 24 Jun 2014 19:48:54 -0700
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Inconsistent stumbling on resume throttle..Was "vanagon syndrome?"
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84 vanagon with 92 inline VW digifant motor and vanagon engine managment
parts...
I queried "what was Vanagon Syndrome" a few days ago, thinking mine was
showing what may be those symptoms...and got a few suggestions based on the
symptoms I posted. Just got in from another drive of about 100 miles,
during which I tried to induce these symptoms and get some sort of
consistent behavior to pass on for you who're inclined to try to diagnose..
.The bucking and missing and bogging that I saw just two times prior to my
previous post...that was occurring much more often on today's trip, but
still not every single time I did ....anything I can think of....It's now
something I must fix before I can use my Vanagon again...with any peace of
mind...
What I am seeing quite often is once the motor is warmed up after about
15 or 30 miles and I let off the gas a little then resume throttle, not
full throttle but just reapply the gas...the engine bogs and burbles and we
lose speed...There is no smoke from the pipe...full throttle doesn't clear
it up, nor does downshifting and going to redline....But if I switch off
the ignition and turn it right back on, everything clears up in a second or
two and it runs fine...then it may or may not repeat that same behavior
next time I let off and resume throttle...or it sometimes just begins to
burrble sputter and miss again...I think this behavior is
throttle-related...but I am guessing because it isn't consistent or
repeatable by anything I have been able to try to induce the behavior...
Ok, more...when I simply shift into neutral and coast for a bit, then go
back to a gear (5sp manual trans) I don't think I get any missing or
bucking...but if I coast down with little or no throttle, then it often
(but not every time) happens when I resume throttle...
When this odd behavior is not happening, the van runs perfectly, I can
go through all the gears, taking it right to redline each time and is
simply purrs! Then 10 miles down the road I might come up behind a slow
truck or encounter a slight downhill and I let off a little on the
gas....and it begins to buck and miss....much more often today, but still
not each and every time I slow up....
It is almost like there is some sort of vacuum leak...but I don't think
there's anything vacuum related in the Vanagon digifant engine management,
is there? Or perhaps it's related to the throttle switch...but isn't that
a 'yes or no' device? On or Off...? I don't see that causing an
inconsistent poor running condition, and one that can be temporarily cured
by shutting off and on the ignition switch...
Anyone care to make a stab at this? Or perhaps give me a direction to
begin my searching? I do have a spare almost everything...I am going to
try swapping the Brain, the coil, and the Temp II sender and I will
probably order a new Throttle switch......I just recently replaced the fuel
pump and the filters...not related to this poor running...
Thanks if anyone cares to respond... Don Hanson