Re: 88 MB Urq questions

[Orin Eman <orin@wolfenet.com>]

> > As for the US MC engine, it forgets about the O2 sensor pretty much
> > as soon as you go on boost and uses one of two RPM based duty cycle tables
> > for the frequency valve... (one table for low boost, one for
> > not so low boost levels).  There is no carry forword of anything learnt
> > by the O2 sensor to on-boost behavior.

> As you showed, the MAC12D is a cut-down MAC11.  I would not expect any
> carry-forward here.

I just remembered something else that may be of interest.  The MAC11 uses
a base duty cycle of 50% for controlling the mixture via the O2 sensor.
The MAC14 (some 89 MC engines and later) has an RPM/MAP based table
of base duty cycles!  So, the fuel metering needs compensation to
try to maintain a given A/F ratio.

> The MB is a single knock sensor engine, like the MC-1.  If the fixing
> for the second knock sensor is present on the engine, would bolting
> a second one on and hooking it up to some instrumentation help?  I note
> your comments in the code about noise from these devices.

A second sensor would probably be deaf to some cylinders.  The dual
knock sensor ECU switches between the sensors depending on which
cylinder is firing.  You'd need some pretty good instrumentation -
like DSP filtering.  Go look on the TI site (www.ti.com).  Somewhere
in the DSP documentation is an application note on knock detection
using their DSP chips.  I'm probably going to get a DSP board and
hook it up to the stock knock sensor and see what I get.

Orin.