Date: Thu, 11 Aug 2011 22:20:15 -0400
Reply-To: Shawn Luft <shawnluft@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Shawn Luft <shawnluft@HOTMAIL.COM>
Subject: Re: Help! Hesitation on the road!
In-Reply-To: <1313114737.32264.YahooMailClassic@web160610.mail.bf1.yahoo.com>
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I had a hesitation problem once that I fixed by changing an electric connection to the fuel injectors.Took a used connector from an `86 Jetta and it was the same fit.
Good luck
> Date: Thu, 11 Aug 2011 19:05:37 -0700
> From: david_vickery@YAHOO.COM
> Subject: Re: Help! Hesitation on the road!
> To: vanagon@GERRY.VANAGON.COM
>
> I appreciate you (Dennis) taking the time to explain this. I didn't understand how it could be the problem if disconnecting the o2 sensor caused the same symptoms. Since my problem isn't fixed and I am looking for solutions, I just found this document that I think is great too. It mostly focuses on the AFM but has a lot of good info and the description of the problem sounds exactly like what I have been experiencing.
>
> www.vanagonauts.com/files/FIxSystemxAFMxproblemsxxxfix.rtf
>
> --- On Wed, 8/10/11, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:
>
> > From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
> > Subject: Re: Help! Hesitation on the road!
> > To: vanagon@GERRY.VANAGON.COM
> > Date: Wednesday, August 10, 2011, 4:39 PM
> > That harness has limited success in
> > solving the problem and part of that
> > solution is the effect of modifying the AFM output. VW was
> > wrong.
> >
> > The O2 sensor circuit is the only circuit that actually
> > calibrates to a
> > signal, a real voltage, not a resistance change. When the
> > signal is weak or
> > there is a noise or ground problem the ECU will continue to
> > richen the
> > mixture until it sees that signal. A bad ground reference
> > or a shorted input
> > lead will even override the effect of disconnecting the
> > sensor. The ground
> > reference is the brown wire that travels in the distributor
> > harness. Often
> > it is connected to a screw at the base of the oil breather.
> > The plastic does
> > not make a good connection. Move it and if the wire in the
> > crimp is brown
> > replace a crimp ring terminal. For wire testing do the
> > following:
> >
> > Disconnect the O2 sensor and peel back the outer wire
> > sheath to expose the
> > outer shielding. Yes this is a coaxial wire.
> >
> > Key on-Engine off, with a sensitive or digital voltmeter
> > measure between the
> > outer shield and a good reference point on the chassis.
> > Should be real close
> > to 0 volts.
> > Measure from center (signal) wire to same reference. Should
> > be .5 to .6
> > volts.
> > Measure from center to shield. Should be same as center to
> > ground.
> >
> > Any stray voltage on that shield gets added to the voltage
> > setting the O2
> > sensor circuit is looking for. So let's say you see .25
> > volt on the shield.
> > The ECU will not reverse and lean out the mixture until the
> > O2 sensor puts
> > out ~1.0 volt. Since normal regulation is somewhere between
> > .2 and .8 you
> > can see where this can mess things up.
> >
> > Dennis
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]
> > On Behalf Of
> > george jannini
> > Sent: Wednesday, August 10, 2011 4:16 PM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Help! Hesitation on the road!
> >
> > I Googled...
> >
> > VW technical service bulletins regarding driveability
> > complaints read as
> > follows- The first details problems with Digifant engines
> > and the second one
> > supercedes the first, acknowledging problems with Digijet
> > Waterboxers as
> > well.
> >
> > --- Begin quote ---
> >
> > Technical Bulletin Group: 24 Number: 92-01 Date: February
> > 29, 1992
> > Subject: Vanagon Intermittent Misfire Model(s): All Vanagon
> > Digifant Fuel
> > Injection Engines
> >
> > CONDITION After driving for 1/2 to 2 hours at a constant
> > speed, vehicle
> > experiences lack of power, cuts-out or stalls, often
> > accompanied by bucking
> > or jerking of the vehicle. In ALL cases, the vehicle will
> > restart
> > immediately.
> >
> > This symptom may not re-occur for several weeks/months.
> > Inspection by the
> > dealer results in nothing conclusive. Some air-flow meters
> > may experience a
> > vibration resonance of the metering potentiometer wiper
> > during extended
> > constant driving. This resonance causes the air-flow meter
> > to supply an
> > intermittent signal to the Digifant ECU. The ECU will then
> > default to a
> > "no-load" condition and reduce the injection time.
> >
> > SERVICE Harness, Part No. 025 906 302, is available to
> > resolve this
> > condition. * remove electrical connector from air flow
> > sensor (see Figure
> > 24-174) * install converter assembly, Part No. 025 906 302,
> > between harness
> > and air flow sensor NOTE If customer complaints persist
> > after performing the
> > above repair, contact your Zone Product Support Specialist
> > (TSM in Canada)
> >
> > ____________________________________________________
> >
> >
> > Technical Bulletin Group: 24 Number: 92-02 Date: April 30,
> > 1992
> > Subject: Vanagon Drivability Complaints Model(s): All Water
> > Cooled Engine
> > Vanagons SUPERCEDES TECHNICAL BULLETIN 24-92-01 (February
> > 29,
> > 1992)
> >
> > CONDITION After driving for an extended period of time at
> > a constant speed,
> > the vehicle may, on occasion, experience a deterioration of
> > performance
> > which may be accompanied by a hesitation or surging. In
> > many cases, after
> > turning off the engine and subsequent re-start or without
> > having taken any
> > action, the symptoms disappear. These symptoms may not
> > recur for several
> > weeks or months.
> >
> > SERVICE To resolve this condition, wire harness Part No.
> > 025 906 302,
> > should be installed. This harness provides improved signal
> > voltage
> > stabilization. * remove electrical connector from air flow
> > sensor * install
> > wire harness, Part No. 025 906 302, between main harness
> > connection and air
> > flow sensor connection.
> >
> > --- End quote ---
> >
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