o2 system testing

[vdub.grego at gmail.com (Matt Gregory)]

No, not going to be at Cincy.  But the offer is much appreciated!

That's strange about the control unit location ... I guess the Bentley is
just a little vague about it.  Although I looked it up on the
bentleypublisher site and mine doesn't seem 544 pages ... I'll have to check
my edition, maybe I have a very early one ... it's very pitiful compared to
the Bentleys I have for my GTI VR6 and an old Rabbit I had.

I need to check my facts now.  I wish I had my Bentley in front of me, but I
could SWEAR that it says that the normal range at idle should be around 74
(dwell) and the range the graphic you linked shows as good the Bentley calls
"limp home."  The information you gave me lines up more with my results.  I
was hitting 28-35 at idle which would just indicate I need a smaller
adjustment, which seems good news to me.  I don't have a dwell meter like
yours, I have a digital multimeter that can measure dwell.  I had it hooked
up to the loose connector near the coil.  Actually, per the Bentley I had
the positive hooked to the blue/white wire and the negative grounded to the
engine block.

I think my o2 sensor is new, but now I can't remember whether I'm thinking
of the Scirocco or the previous Rabbit. :-)

If you don't mind, can someone look up the dwell specs in the back of the
exhaust section in their Bentley so I can have something to verify mine
against?

Thanks again,
matt.

On 5/30/06, Timbo <timjmcconnell@gmail.com> wrote:
>
> Hey, matt - Are ya gonna be at cincy? I'll be doing A/F tests there
> with my meter.
>
> Yeah - Roccos have the box in the raintray. Rabbits and things have it
> under the glovebox. A pain to get at in Cabriolets because of the
> kneebar.
>
> I don't know what the bentley is talking about with the crankcase
> breather thing.
>
> If you do pick up a new oxygen sensor - one of the $35 Bosch universal
> ones - I'd be happy to install it and solder it at cincy and then fix
> your A/F for ya. I have the socket for it, and the fun electrical
> stuff too.
>
> You are going off of that test plug near the coil, right? With a dwell
> meter- with the car COMPLETLY warmed up - This is my test: It needs to
> sweep in the area of 45? ? 7?. So if you are in between 38? and 52? -
> you are in the ideal range. If the reading is below 23? or above 59?,
> then you need to adjust the mixture.
>
>
> http://www.vintagewatercooleds.com/tech/Techtips/Timbotechnotes/airfuel/pics/CISdwell.jpg
>
> --Timbo
>
> On 5/30/06, Matt Gregory <vdub.grego@gmail.com> wrote:
> > This weekend I decided to do some testing on my 86 8v.  I was going to
> start
> > with timing, but the timing test said to make sure the o2 system was
> > functioning properly, so I started there instead.  Of course the o2
> testing
> > section says to make sure the timing is set correctly so it's a
> catch-22.
> > But anyway I didn't think either were that far off because the
> seat-of-pants
> > meter indicates everything is pretty much ok.  I'd just like to do some
> > verification and fine tuning.
> >
> > So my o2 system so far is failing miserably.  I got through the quick
> check
> > test in the Bentley where you warm the engine up and read the dwell
> meter
> > (I'm using a dwell), then remove the crank case ventilation hose and
> plug it
> > and the reading should drop and then hunt around 23-27 (IIRC).  My
> results
> > at idle were in the "limp home" range and with the ventilation hose
> plugged
> > around 12-18.  It never dropped and then hunted it just went straight
> there,
> > so I don't know if the 12-18 is the drop or the hunt.  I should mention
> my
> > cat is empty, but since the o2 sensor is before the cat I don't beleive
> this
> > should affect these results.
> >
> > So if I read between the lines it seems like my mixture is low and
> perhaps I
> > can correct it by adjusting it using the 3mm allen in the hole near the
> fuel
> > distributor.  But I thought this was a setting you didn't want so screw
> with
> > unless you're sure of it so I wanted to solicit some second
> opinions.  Or
> > should I continue with the rest of the o2 system tests?  But I predict
> that
> > all the tests are going to yeild similarly low results.  I'm thinking
> what I
> > should do is try to adjust the mixture to get the "quick test" acting
> more
> > normal and then verify the remainder of the tests.
> >
> > ALSO, has the location of the o2 system control unit changed?  My
> Bentley
> > claims it should be behind the glove box, so I went looking there
> because I
> > remembered having a leak problem so I wanted to check out the electrical
> > connections.  But I found nothing.  Mine seems to be in the same
> location my
> > Bentley claims the 16v CIS-E unit is, behind the rain tray on the driver
> > side ... it's a big black box lableled "Jetronic."
> >
> > Thanks in advance,
> >
> > matt.
> > _______________________________________________
> > Scirocco-l mailing list
> > Scirocco-l@scirocco.org
> > http://neubayern.net/mailman/listinfo/scirocco-l
> >
>
>
> --
> Timbo!
> Location: Glenside, PA!
> www.vintagewatercooleds.com/tech
>