Date: Wed, 30 Jul 2014 16:34:55 -0700
Reply-To: Don Hanson <dhanson928@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson928@GMAIL.COM>
Subject: Re: Another question about O2 sensors..
In-Reply-To: <CAB2RwfjKYZURxE3ONzSi=5MPUAVX8wrGUPuV0rTTVjb2xusYPA@mail.gmail.com>
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Well lots of confusion and I certainly appreciate all the answers..... I
called the guys at Van Cafe and asked them, since they sell a lot of the
single wire O2 sensors..They ran out to the shop and asked their
mechanic...he says people only need the signal wire...everything else that
was connected for a 4 or 3 wire sensor is superfluous once you swap to the
single wire one.
The wire I am/was asking about, it comes out of the insulated
sheath....in my case, that insulated tube is not braided but it is a hard
solid lead kinda tube that dives into a large segment of the harness headed
to the ECU and the air intake....The wire is black and is the same size as
the purple signal wire and insulated from the sheath, just like that signal
wire...
I guess I should just drive it and see if I am back to my normal gas
mileage...I doubt the former O2 sensor was connected wrong,,,since I've
always seen 23-25mpg except recently when I was having the issue with that
old sensor......so if I am down some now, with the ground not connected, I
would guess it needs to be hooked to something like the block or chassis...
That is the problem with any swap done by a previous owner rather than by
you...One can never be 100% sure exactly what the fellow did/used/ fudged,
etc...He told me when I got the van that the motor was from a 92 Cabriolet,
which I have always ordered parts for , and they are right...so I believe
that...but where I sometimes get stumped for a while is exactly where did
he connect the stuff from the Cabriolet to the stuff left over from the
WBX? A lot of the parts are identical and interchangeable...but some are
not....mainly only the hard parts. I think the O. Owner re-used every
possible part from the Vanagon so as to get it done cheaply. The Bently
book I have says my motor is IDigifant II and I've never seen anything that
makes me think otherwise..
It's too late this evening but I am also going to call the boys at
Techtonics Tuning and ask them....Since I bought a lot of stuff from them
and I made friends with them, send them business from time to time, they
are always pretty helpful and cheerful with sharing information when I get
really stumped...
Now for unrelated but Vanagon chat...I have been driving my worker van to
Hood River, Oregon and working on a restored victorian house right in
downtown HR....From my work site in the drive way I can see two Syncros, a
normal WBX westie and a bay westie...and I can't see more than about half a
block for all the oak trees....3 or 4 GM vans, too...
On Wed, Jul 30, 2014 at 2:23 PM, Neil N <musomuso@gmail.com> wrote:
> Don. I don't wish to mislead your search for O2 perfection, but Marks
> comments reminded me of the O2 connector on my swap engine. (Motronic)
>
> Image of connector: http://tinyurl.com/kdgvmkg Though the wire
> colours etc. are different, is this what you see? If so......
>
> I'd asked of this black wire some time ago. Looking online at a more
> user friendly Motronic wiring diagram, that black wire leads to the O2
> shield which connects to the engine block (ground).
>
> Seeing that black lead led me to believe that it wasn't connected. If
> memory serves, in it's OEM form, it was looped "back" and taped"
> within the harness. I'd simply uncovered it during wiring harness
> work.
>
> Neil.
>
>
>
> On 7/30/14, mark drillock <mdrillock@cox.net> wrote:
>
> > Unless you know the exact year and model car that your inline 4 wiring
> > harness came from it may be difficult to know exactly how it should be
> > connected. Because VW used different variations of that 4 pin O2 sensor
> > wiring there is no guarantee that what you had before was right either.
> > The old O2 sensor may not have been an exact match to the one that
> > harness was fitted with from the factory.
> >
> > In any case, the shield for the coax should be grounded but only at 1
> > end. So it needs a ground at one end and no connection at the other end.
> > Never should both ends be connected to ground. From your description my
> > guess is you have a harness where the shield is connected only to pin 3
> > of the 4 pin. If so that would mean it should have a wire running from
> > there to the engine, grounded to bare metal.
> >
> > But even if that capped wire is supposed to be grounded it is possible
> > that you would notice no big difference by doing so. That is because the
> > grounding of the shield is only to let the shield absorb stray
> > electronic noise that otherwise could be picked up by the inner signal
> > wire. Since the normal O2 sensor signal is so small, the circuit is more
> > susceptible to interference and that is why the signal wire from the
> > sensor to the ECU gets the coax shielding. So grounding one end of the
> > shield lets it protect the signal wire from electronic noise but it
> > isn't used by the ECU for processing the O2 sensor signal. It is not the
> > reference ground, that is elsewhere.
> >
>
> --
> Neil n
>
> Blog: tubaneil.blogspot.ca
>
> '88 Westy http://tinyurl.com/c8rlw6p
>
> '81 VanaJetta 2.0 "Jaco" http://tubaneil.googlepages.com/
>
> Vanagon VAG *Gas* inline-VR Engine Swap Group:
>
> http://tinyurl.com/d7gd5ej
>
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