[urq] knock sensor question.

[Buchholz, Steven]

... cleaning up my inbox I saw the message below ... didn't appear to be
any replies ... 

I've looked into the knock sensor situation a bit over the years ...
love to retrofit something to my car someday ... here's what I've
learned:

One option that some have contemplated is to incorporate a Saab APC
system into the car.  I haven't looked much into this myself, but I
believe there are folks who have retrofitted a system into their
turbocharged Audis.  If you are interested do a web search and you will
find out more.  My concern about this alternative is that the spark
timing is controlled by the ECU ... it isn't clear to me whether or not
there would be any interaction between the two systems.  

My original plan was to see if I could retrofit a control system from an
MC engine (MAC-11 or MAC-13) to the WX.  It should be possible to do
either, but there's the nagging question about whether or not the knock
sensor(s) will operate properly if not attached to the block in the
factory way ... based on that concern I have pretty much concluded that
if you want to have knock sensing capability you might as well swap in
an MC engine.  I'm thinking MC-II myself ... you get dual knock sensors
and slightly higher static compression.  

The thing I really like about Audi's knock regulation mechanism is that
it will first retard the spark, but if that doesn't work it will open up
the WGFV (wastegate frequency valve) which will reduce the maximum
amount of boost that is applied to the intake manifold ... 

... all that said ... it should be possible to connect up the
electronics from an MC engine to a WX ... just be careful to make sure
that you have the proper reference pin location for the MC.  

... depending upon how wacky you want to get, there are other
alternatives to "classical" knock detection that could be used on a WX
engine without any modifications.  There is a fairly modern system
called ION sensing ... this actually looks at the ionization signal in
the combustion chamber by observing the spark plug signal after the
charge is ignited.  I would love to have a system like this to use for
my car ... probably set up with a full-on EFI system ... I've been a bit
out of the loop for a while on what might be available here ... if you
are interested check out diy-efi.org or do a general web search on ION
sensing ignition systems ... 

Steve B
San Jose, CA (USA)
> 
> I was wondering if it was possible to hook up a knock sensor 
> on a pre MC motor like on my 82.