[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
o2 system testing
Ok, I checked my Bentley when I got home, and here's what I was
remembering:
"To test the control unit's stand-by or limp-home mode, remove wires
from the thermoswitch, but do not bridge them. Run the fuel pump and
turn on the ignition. The duty cycle should be a steady 50% +- 2%
(45 +- 2 on a dwell meter)."
and
"To test the control unit's normal running, mixture regulating
function, remove the wires from the thermoswitch, but do not bridge
them. Disconnect the green wire from the oxygen sensor, and ground
the green wire as indicated in Fig. 5-4. Run the fuel pump, and turn
on the ignition. The duty cycle should be above 87% (78 on a dwell
meter). Stop the pump and turn off the ignition"
This is in FUE 5.1 under Checking Oxygen Sensor System Control Unit.
Then the stats in the back of the FUE section say:
Control unit duty cycle (dwell equivalent)
- cold enrichment function ..... 80% +- 2% (72 +- 2)
- stand-by mode function ..... 50% +- 2% (45 +- 2)
- rich-mixture limiting function ..... 87% (78)
- lean-mixture limiting function ..... 20% (18)
And I found out why my Bentley seems a little lighter than expected.
It only goes through '89 ... I guess it's been with the car for quite
some time. Is this the same information found in everyone else's?
Thanks again,
matt.
On 30 May 2006, at 11:07 AM, Timbo 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