Weird Idle problem. (idle kickdown causes stall on cis-e)

[amalventano1@comcast.net (Allyn)]

hrm, i suppose it is #7.5. it was actually #8 at one point in time:
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image42.htm
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image41.htm
until i got happy with the sawzall that is:
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image68.htm
the trailer sits watching in horror:
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image80.htm
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image79.htm
hrm, wheres the other half?
http://scirocco.dhs.org/vw/pics/0-allyn/project/imagepages/image85.htm
oh, there it is :)

heh
Al

----- Original Message -----
From: "Euroroc II" <flaatr@yahoo.com>
To: "Allyn" <amalventano1@comcast.net>; <scirocco-l@scirocco.org>
Sent: Friday, September 20, 2002 6:56 PM
Subject: Re: Weird Idle problem. (idle kickdown causes stall on cis-e)


> Hey Allyn in your sig file shouldn't the 86.5 Occo 16v Trailer (dotting
> 'i's across the country, rocco #8) officially be rocco #7.5?
>
> Just asking...
> -RGK-
>
> At 04:59 PM 9/20/02 -0400, you wrote:
> >The rieger does the same exact thing:
> >     our cars have an idle fuel cutout. if the throttle is at the idle
> > position,
> >it closes the switch on the throttle body. if the idle switch is closed
> >and rpm
> > > ~1600, this results in the jetronic box applying ~-50ma to the DPR
> > until rpm
> >drops below ~1400 rpm. This lets the engine coast down with no fuel (as
> >opposed
> >to the fuel injection attempting to supply correct fuel during a coast).
> >     as a side note, there is a time delay. the ecu must see the idle switch
> >closed for >1/4 second in order for it to start the idle kickdown process.
> >
> >the reason we get our stall is a combination of any of the following:
> >
> >- dirty idle contact, resulting in longer than 1/4 sec lag for ecu to see the
> >switch closed (switch debouncing is accomplished by a r/c circuit in the
> >jetronic box), resulting in the kickdown occuring right at 1400 rpm or
> >slightly
> >below, possibly resulting in a stall if you get it just right.
> >- sluggish/clogged fuel system, resulting in a lag as the DPR attempts to get
> >back to normal control pressure (<1400 rpm). if it cant get pressure back
> >quick
> >enough, you stall.
> >- vacuum leaks (may not be enough to mess with idle, but can be enough to
> >cause
> >a stall in this kickdown condition).
> >- tuning: the kickdown circuit recovers to the standard +5 to +10 ma DPR
> >current
> >range. if you adjusted/tweaked your DPR current out of this range, your
> >fuel/air
> >will be out of whack immediately following the kickdown. this may be enough
to
> >cause a stall.
> >- idle speed set screw adjusted too low. if the ISV is already at near max
> >open
> >dwell during a normal idle, it cant open any further to correct for the
> >downward
> >swing during a kickdown, meaning its harder for the system to recover a
> >low idle
> >speed, and you stall.
> >
> >     and finally, the reason the problem goes away when the a/c is on: idle
> >kickdown is disabled with the a/c on to prevent compressor loading from
> >stalling
> >the engine during a kickdown event.
> >
> >     I plan on messing with these things one at a time until i nail it,
> > but i am
> >fairly certain that its a combination of the above thats causing it right
> >now. i
> >have a feeling simply opening the idle speed set screw a bit will fix the
> >problem.
> >
> >HTH
> >Al
> >
> >Allyn Malventano, ETC(SS), USN
> >87 Rieger GTO Scirocco 16v (daily driver, 180k, rocco #6)
> >86 Kamei Twin 16V Turbo Scirocco GTX ('it has begun', rocco #7)
> >86.5 Occo 16v Trailer (dotting 'i's across the country, rocco #8)
> >87 Jetta 8v Wolfsburg 2dr (daily driver, 260k, 0 rattles, original clutch,
> >driveshafts, wheels :)
> >
> >
> >----- Original Message -----
> >From: "Euroroc II" <flaatr@yahoo.com>
> >To: <scirocco-l@scirocco.org>
> >Sent: Friday, September 20, 2002 4:45 PM
> >Subject: Weird Idle problem.
> >
> >
> > > Heres one for ya...
> > >
> > > My car idles perfectly, closed loop @ 870 RPM, smooth, stock cam. new
> > > distributor & Cap & Rotor, differential pressure regulator & fuel
> > > accumulator are new too along with plugs, filter, and oil. The alternator
> > > is working fine and the battery is happy, 13.5-14V from alternator, no
hard
> > > cranking when starting,  etc. etc. etc.
> > >
> > > When I drive the car and come to a stop, slowing in gear to below 2K
before
> > > letting the clutch out the engine speed will drop to 500 RPM'ish bog for a
> > > split second then return to perfect idle (or lower and occasionally stalls
> > > although not that often) . This is repeatable and annoying. Revving up and
> > > letting it drop is fine, holding at a higher RPM and letting it drop is
> > > fine. the problem only seems to happen when the car is driven, higher RPM
> > > under load and let it out of gear under 2K. Letting it out of gear above
2K
> > > is good, engine returns to idle without dipping.
> > >
> > > Strange thing is that if I have the A/C on the entire problem goes away.
> > >
> > > I've had it in the shop several times, for many days, and they can't seem
> > > to figure it out. The problem remains so I ask the group...
> > >
> > > Anyone have this problem before and how did you fix it? I may have left
out
> > > a detail or two so ask me any questions you have.
> > >
> > > -Raffi
> > >
> > >
> > > _______________________________________________
> > > Scirocco-l mailing list
> > > Scirocco-l@scirocco.org
> > > http://neubayern.net/mailman/listinfo/scirocco-l
>
>
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