16V auto passat TB - nipple for butterfly bypass?

[mk1mark at gmail.com (Mark F.)]

On 8/15/06, Dan Bubb <jdbubb@verizon.net> wrote:
> If you're talking about the 1/8" diameter or so nipple on the primary side
> of the TB then, no, it isn't open to the manifold side of the throttle
> plates at idle.


Hmmm, didn't notice an 1/8" nipple on it...


> If you're talking about the 5/16" diameter nipple on the secondary side of
> the TB, yes it is open to the manifold at all times.


Yup, this is the one I was talking about...  I now have an
unrestricted large diameter tube running from this nipple to the
rubber boot before the TB, and it still doesn't let enough air by to
keep an idle.  Sometimes it *barely* keeps running, but usually
stalls.  I adjusted the stop on the TB so that the butterfly is always
cracked a bit, which works, but I'd rather not resort to "ghetto"
tuning like that...  Since I have grafted in a knock sensing ignition,
I'd like to reap the benefits of that system, but if it's not
receiving a closed throttle signal at idle then it's obviously not
optimizing the ignition timing for an idle condition.  I'd also guess
that when adjusting my ignition timing w/ a timing light that the
reading might be different if the switch was engaged or not,  making
the results inaccurate (or am I splitting hairs here?)

I used a CIS-E (or Digi?) TB last time w/ the "external" WOT and idle
switches and had this exact same problem ("solved" by the same
butterfly stop adjustment).  I'm guessing the 2.0L just needs more air
at idle than I can give it via the methods I've tried, or something is
wrong with my setup.  If nothing's wrong, then I guess I'll have to
plumb in an additional bypass and make it adjustable...

Later,

Mark.