Timing Retard w/o knock & MAF oscillations

[Michael Davis]

In message <4.2.0.58.19990924105438.00955100 at 127.0.0.1>,David Cooley writes:
>At 10:45 AM 9/24/1999 -0400, you wrote:
>>In trying to understand some Diacom data. I'm seeing "knock retard" being
>>introduced, but No "spark control counts" being sensed..  Will the ECM
>>retard the timing when the table jumps from LV8 column to LV8 column and
>>the requested advance decreases in this column jump?
>>
>Nope... Would just show as a different value in the timing advance data... 
>retard is when it pulls timing due to knock and it's modifying whatever 
>value is in the timing table.

So then the original question goes back to, "How can Knock Retard be
introduced by the ECM, when there are no spark control counts"?

>
>
>>(BTW, while I'm sending this email, I'll ask...  Would anyone know why my
>>  air flow thru my MAF would oscilliate at high load/flow?  I have a PDF
>>  graph of what I mean at:
>>                 http://www.eecis.udel.edu/~davis/z28/ecm_swap/165chart.pdf
>
>It appears it may be due to being sampled during an intake valve opening, 
>or between openings...  The air flow will pulse.

This oscilliation is very repeatable.  (something I wouldn't expect if
the signal was aliasing..) If it is indeed the intake, then would this
be and indication that I need a larger plenum (air reservoir) and/or
larger/shorter intake/runners to calm the pulsing?

thanks
mike