Date: Mon, 28 Jan 2002 01:04:01 -0500
Reply-To: Laurence Smith <lsmith@COGECO.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Laurence Smith <lsmith@COGECO.CA>
Subject: Persistent running rich problem finally fixed. Here's how.
Content-Type: text/plain; charset="iso-8859-1"
Hello List,
After nearly 4 months of fiddling I have finally solved my rich
running condition on my 90 Westy. Perhaps my fix will help someone
else.
As background here is (was) the main symptom:
* running very, very, very, rich after warm up, van not driveable,
billowing black smoke
* when warm, engine running, remove TempII wire, or AFM pigtail sets
the computer into open loop and rich condition went away
* disconnecting O2 sensor did nothing
Attempted fixes:
* replaced TempII, ECU, AFM, O2 sensor, fuel pressure regulator, all
injectors, ignition wires, plugs, cap, rotor, idle stabilizer control,
ignition switch (I was desparate)
* continuity in ALL wiring was good
* rebuilt throttle body & idle switch, cleaned idle stabilzer valve,
checked all vacuum lines, checked all connectors, adjusted timing,
tested Hall sender
* replaced battery and engine block big grounds, soldered all 7 engine
ground wires with new eyelets, added a ground to the AFM and the right
side of the engine.
NOTHING WORKED! VAN NOT DRIVEABLE FOR 4 MONTHS.
Dave Homer (London, ON) of this list was kind enough to pop over to my
house and help out. He changed this and that but admitted this was a
tough one. David Beierl in NJ, also on this list, helped me out on
the phone. Many others on this list e-mailed me suggestions. Joel
Waker, on this list, spent time writing me an extensive e-mail with
suggestions. Thanks to all for your help.
The solution:
* On the Digifant ECU terminal 19 there is a brown/black wire that
grounds the green O2 sensor outer wire jacket. It is brown/black on
the 90 Vanagon, but is a different brown combination on other years
(says Bentley).
* This wire was missing in my engine compartment. It was no where to
be found. Not peeking out of the harness, or under some crud. It was
gone. The previous owner (July 2001) must have snipped it off. Who
knows.
* I have no idea how the van drove acceptably August-September but it
did. Perhaps an internal ground in the harness.
* To fix it I stripped back the harness connector at the ECU, attached
a ground wire to the brown/black wire and led it back to the engine
and grounded it. Voila problem gone. Runs great! For fun, I removed
this ground and the black smoke appeared again.
What I have learned:
* Review the Bentley wire diagrams. Really, really review them.
Learn all the wires that should be there. The diagrams are extremely
accurate.
* Trust the resistence and voltage specs in Bentley. Don't second
guess them. EXCEPT: Adding the AFM Vanagon Syndrome pigtail harness
changes the Bentley test procedure for the AFM. A VW Technicial
Service Bulletin mentions this.
* Be methodical about testing every Digifant component. Don't ignore
any of them.
* Find a friend that can swap out Digifant components.
* The O2 sensor, its connector to the green coax, the impedence this
sets up, and how the ECU interprets volts when warm is extremely
important. I was under the false assumption that if the O2 sensor was
disconnected, there was no influence on the ECU. Wrongo!
I hope no one else goes through the pain and money I have had to
endure for a simple missing ground wire.
Laurence Smith
Hamilton, ON
90 Westy (fanumbos)
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