Knock Detection

Tony Cooper tony.cooper at virgin.net
Fri Nov 7 11:07:13 GMT 1997


Ken Mayer wrote:
 
> Huh?  There is no unburned fuel near the spark plug when the knock occurs.
> The plug has already ignited it and the flame front is some distance away.
> 
> Ken
> :-)


Fair point, but what about pre-ignition...????, The plug hasn't ignited
the mixture yet, so the sharp edges of the thread could be a detonation
point.....

Just a couple of side points. Has anyone considered the following...????

Using an FPGA and DSP, why not use an optical decoder to measure
accel/decel curves from an engine, FFTing the result, and getting a
frequency responce which - co-incedentaly gives peaks when pre/post
detonation occurs....

Or... and this one may get a few responces.... Using the spark plug
(just a boring old, nothing special standard spark plug that you use to
ignite yer mixture) to measure BMEP, and therefore detecting detonation
(and here's the cute bit) AND TORQUE from that cylinder....Feeding this
information back to the EFI system so the system will tune itself...!!!!
All it needs is some driving time, and the EFI will produce its own
maps, which adjust themselves as the engine ages....

Go on then - flame me if you wish...

This thread is getting a little bit more like what I would expect from a
EFI mailing list....
Just my tuppenys worth... :>

Tony
-- 
Sent By Tony Cooper.
ACPA Automotive Electronics - The IM5 is nearly here......
email: tony.cooper at virgin.net
Allow at least 10 working minutes for reply. ;)




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