Date: Mon, 26 Oct 1998 20:15:02 -0800
Reply-To: Austin <austins@IX.NETCOM.COM>
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: Austin <austins@IX.NETCOM.COM>
Subject: Re: idle surge diagnosis?
In-Reply-To: <3634D833.9C861E29@halhinet.on.ca>
Content-Type: text/plain; charset="us-ascii"
At 03:14 PM 10/26/98 -0500, you wrote:
>Thank you...Thank you...Thank you...Kenneth Lewis
>
>This hitherto totally undocumented cure to the surging idle problem belongs
>right up there with the famous capacitor fix to the dreaded Vanagon Syndrome.
>For those who don't know what I'm talking about here is an excerpt of Ken's
>missive:
>
>> The Air Bypass Valve is adjustable but nowhere will you find a procedure. I
>> experimented with it trying to (unsuccessfully) fix high HC output. I
>> produced a very similar symptom as yours. (idle speed going up and down in
>> a regular fashion every couple of seconds) To access the (Idle Stabilizer
>> Valve) adjustment unplug the electrical connector and remove a 2mm allen
>> set
>> screw from the center. Now reconnect the plug and pull back the rubber
>> boot. The adjustment is accessible, while the engine is running, with a
>> 2.5mm allen between the two wires. Turn the allen CCW to raise the idle, CW
>> to lower.
>
>We haven't found a VW mechanic within all of southern Ontario that knew how
>to fix this problem. The standard mantra was get a new Idle Stabilizer
>Control Unit or Idle Stabilizer Valve or both.
>
>IMHO This procedure should be written up in entirety and put into a special
>spot in the archives.
>Larry
>'86 Syncro Westfalia
>
This worked for me (wrote it up ~ a year ago):
Date: Fri, 7 Mar 1997 05:57:42 -0600
From: Austin <austins@ix.netcom.com
Subject: RE:'87 High/wandering Idle-a solution???
STABILIZING DIGIFANT IDLE:
OK folks-y'all aren't gonna believe this, but (I believe) I've discovered
something never before covered on this list, or in any manual for that
matter (& please correct me if I'm wrong, or if what I'm about to relate is
totally off base). This relates in particular to my '87 2wd Digifant, & I
only assume to other similar setups, VW or otherwise.
First, make sure everything else has been checked/corrected (timing, O2
sensor, coolant temp. sensor, good/working/not 'lazy' thermostat, operating
throttle switch, mixture setting, especially make sure the Air Bypass Valve
is clean and free (see recent posts, esp -dan alias Rocko FlameFart on
2/3/97) etc, etc, etc.;
2nd, the engine is at normal operating temperature;
3rd step: with the engine idling - any speed - pull the electrical connector
from the Air Bypass Valve (silver cylinder ~ big as your thumb, sitting top
center of the engine); your idle should go up/down to 750 rpm; if not,
adjust the idle adjust screw on the throttle valve (where the throttle cable
attaches).
4th step, reconnect the electrical connector to the ABV & note what happens
- usually the idle will surge up to 1500+, then slowly come down to about
1000 rpm (on occasion it will either not change at all, or actually lower
the idle to 500 rpm or lower-engine dies, etc - just note what happened when
you reconnected the connector.
5 shut off engine, disconnect the ABV connector again.
NOW IT GETS TRICKY-go slow; drop the following part & you'll be sorry.....
Between the 2 electrical prongs of the ABV itself is a barely visible silver
colored set screw; note that it sits ~ flush with the 'floor' of the socket.
It is a cover screw that seals the good part we're going to get at after
it's removed. Use a 2mm hex wrench to remove it-NOT a ball type hex wrench,
as the set screw may roll off the ball end just as it clears the hole, &
*will* bounce to that place where you lost all the things in your life that
you have to wait for death to ever find again-fondly remembered SO's, pocket
knives, good lighters, etc. (ie-use a rag underneath + a magnet nearby just
in case...)
OK, you got it out safely; now take a 2.5mm (yes, larger than the cover
screw) hex wrench, insert it carefully into the hole - ~1/2 inch - & snuggle
it into the invisible hex screw you *will* feel inside; memorize the
position of the short right angle of the hex wrench sticking out.DON'T TURN
IT YET-resist the false God of 'I gotta see what happens'...
Per step 4 above; if the idle jumped way high & only came down to 1000+,
then turn the 2.5mm hex 1/8 turn clockwise (viewed as if looking directly
into the hole) NO MORE THAN 1/8 TURN!!!! If by (rare) chance the idle
actually lowered or was unaffected in step 4, then turn the hex wrench 1/8
turn (no mo') counter-clockwise.
Re-install the the tiny cover/set screw (down to flush), reinstall the
connector, put the two hex wrenches in a baggy & go for a ride. You'll get
amazingly proficient(sp?) at hopping out, doing a quick adjustment, & go
roaring off.
When you get it right, the idle will edge up when it's supposed to-AC turned
on, power steering at full lock, or at initial start a surge to ~1200 rpm
settling to 800 in a few seconds.
But most of all remember that tiny adjustments make big differences in how
the idle behaves - it's one of those situations where if you get too far out
in left field while you're puttzing around you probably won't get back close
to where you started. Remember, this is a $200+ part at the dealer!!!
And my disclaimers are first a heart-felt apology if this info is such
common knowledge that everyone else *but* me knows about it, & second -
again - remember that tiny adjustments make big differences in idle
behavior; as I got mine close to where I wanted it, I was making barely
perceptable adjustments that were making very noticeable changes to the idle.
Austin
(by the by, don't forget to re-solder all the cold solder joints & other
places where things have been over heated from bad solder joints in both the
ECU box under the bench seat and the idle stabilizer control box behind the
passenger side tail light; I was amazed at how many there were in both of
mine, & how much better the ol' bus ran after doing this <I used silver
solder).