Date:         Wed, 26 Apr 2006 00:31:08 -0400
Reply-To:     "Daniel L. Katz" <katzd54@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Daniel L. Katz" <katzd54@YAHOO.COM>
Subject:      idle and black tower

list:

interested in discussion of following $0 successful fix of very poor idle
on '84 1.9l.

essentially, pulling the 3/4" hose off  black tower outlet, venting blow-
by to the atmosphere, and plugging completely the free end of the hose,
completely solved the problem. she idles smoothly and beautifully at 900
rpm. to finish, i'll have to use a long 3/4" hose to conduct fumes out of
engine compartment, and plug the intake port directly.

i really put this off for a long time because she ran so well otherwise.
in the interim i experimented with conventional pc valves intalled inside
the 3/4" hose oriented so as to stop a front fire from entering the
crankcase, and modified not to close at high blow-by pressures - but
always ran into at least a noticeable amount of trouble building up
crankcase pressure, with symptoms such as oil eventually rising and
leaking out of the dip stick tube.

a valve routing the blowby down the usual route to the intake
off-idle, or a vent to the atmosphere at idle, would be the optimum system.

the van has a bit over over 200 k miles, and the black tower is certainly
original. possible the tower is malfuncting, perhaps running wide open all
of the time, but my experience with restricting the flow downstream
suggests that a possibly more restrictive (at idle) replacement would lead
to the same sort of crankcase overpressure - just too much blow-by. also,
she idles best with the intake port completely sealed. i have not measured
the compression, but the engine is "loose", as it doesn't stop turning
immediately on shut-down, and the engine will not hold parked on even a
very modest incline.

all standard electrical tests related to the afm check out, i've done the
capacitor modification, coolant temp sensor ii is fine, grounds are fine
(maybe 10 mv between block and frame/body/ecu case), o2 sensor is fine,
and i run initial timing 12 deg btc (i.e., with idle stabilizer bypassed).

today's fix was the result of a propitious break down su afternoon, 50
feet from home, under a story book sky at 70 F, where she would start and
then immediately konk out, and stepping on the gas would not keep her lit -
in fact, it felt as though the throttle cable was broken or disconnected,
which was the first thing i checked.

thanks,

dan