Date: Sat, 20 Nov 1999 12:00:15 1000
Reply-To: P & J Lander <pjlander@OZEMAIL.COM.AU>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: P & J Lander <pjlander@OZEMAIL.COM.AU>
Subject: Re: [Syncro] Oxygen sensor questions...
Content-Type: text/plain; charset=us-ascii
Digifant will run perfectly OK with the O2 sensor disconnected so that could not be your problem.
(disconnect it and see)
It sounds like it may be related to your AFM or you may have an air leak around that area.
If your van backfires it may bend the AFM flap spindle causing the flap to stick intermittently, maybe sticking when the AFM is hot and when it has run for a while the air flowing through it cools it down and allows the flap to operate properly.
-----Original Message-----
From: Roger Bowman [mailto:bowmanrp@earthlink.net]
Sent: Saturday, November 20, 1999 6:22 AM
To: SYNCRO tech mailing list; VANAGON Mailing List
Subject: [Syncro] Oxygen sensor questions...
From: "Roger Bowman" <bowmanrp@earthlink.net>
Greetings:
I am tracking down a warm start/drivability problem on an '89 syncro westie.
After the first start of the day, each following start will light off like
normal, and then settle into an uneasy idle, around 500-600 rpm indicated
(as opposed to 1100-1200 indicated normally), with no power. There is no
power to accelerate, and the motor will not rev even with wide open
throttle. The motor will usually stall, but if it does not, after 10-30
seconds of poor idle/no power, the motor will surge into normal idle and
power.
Without fail, turning the motor off and restarting (either by compression or
starter) corrects the problem immeaditely. I am suspecting Oxygen sensor...
Recent work: New Temp II sensor, new fuel filter. Digifant box replaced
with rebuilt Bosch unit.
Diagnostic Info: Using my new Fluke 87...
Looking at the Oxygen Sensor: Engine fully warmed.
- Connected to Harness/Digifant:
I can see the crossovers; voltage ranges from zero/little negative
(-.05v-0.0v) to over .9 volts, but the voltage seems to spend most of its
time in the lower range. I frequently was able to see the digits resolve in
the lower range (around 0.0v), with a crossover about once every 1.5
seconds. The sensor spent a very short time at the higher voltage, and then
returned to the lower voltage. This was pretty consistent; lotsa time at
low/zero volts, short spike to higher voltage, quick return to lower
voltage. Average voltage indicated by meter: .3v or so.
- Disconnected from Harness/Digifant:
Digifant side: about .38 volts
Sensor side: camped out at close to zero. Poor running; replicates
original problem
- Pulling the idle stab hose caused the o2 sensor output to soar to
0.9V and idle to smooth.
- Pulling the vac hose from the FI pressure regulator and plugging it
did not show any change.
So: I'm thinking sensor...and my thoughts cost about $150 or so.
So I pull the sensor and do the bench test thing; find about 3.5 ohms across
the heating element connection, and when heated with a propane torch, the
voltage output climbs from 0.0V to 0.9 volts, and falls quickly (within a
second) when the flame is removed.
Sure would like to confirm a bad sensor before spending all that money; but
frankly, I'm still not sure it is the Oxygen sensor at all. I expected more
crossovers then just one every 1.5 seconds, and I would have expected the
average value to be close to "Stoich" - which I thought was .45v from the
sensor.
Any help is appreciated...in advance.
Roger Bowman - bowmanrp@ earthlink.net
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