At 04:52 PM 1/20/2002, van man wrote:
>Throttle switch led and Fi led work correctly when
>idling and wide open.
>temp 1 - hovers around 1.24/5 up to 1.28 once

Air temp, seems reasonable.

>temp II - hovers around .14/5

Engine temp, seems reasonable.

>OX - fairly wild, occasional - to 6.3

Should be bouncing around, but never over a volt.  If it's actually going
to six volts, prolly a leak to the heater leads inside the sensor.

>AFM - around 3.5 - couple of checks showed 3.8/9

Should vary roughly linearly with throttle opening, up to somewhere near
five volts.  It actually reads the AFM position, so constant throttle with
changing engine speed will give a changing reading, but you should be able
to make it follow your foot short-term.

>When the bucking was occuring, numbers seemed to hold
>steady, although FI light flicked on and off wildly.

That would certainly cause bucking...light should flash for each injector
pulse, at running speeds looks continuous.

>Also, battery level down to low 11's during bucking,
>even 10.9.  still bucked a time or two at battery
>level of 12+, but when bucking was bad, battery level
>was always in the 11's.

Bingo.  Bad ground somewhere, or possibly bad supply voltage to ECU.  That
voltage is what the ECU is seeing, not what the battery is
delivering.  Careful study of Bentley might show  exactly which ground is
the main candidate.

The main weakness (as well as one of the strengths) of the Digitool is that
it depends on ECU ground for its ground reference.  Bearing that in mind,
you can use its external probe to look at various grounds.  The *most
negative* reading you find is the "best" ground.   Ideally it should be
very close (millivolts) to the negative battery terminal.

david

--
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"