Ion Gap Sense Questions

[robert dingli]

Rod asks
> Can any of you GM guys tell me where the capacitor goes in figure
> 8 in John Auzin et al's paper from SAE '95?  I'm guessing between the
> sense amp and the coil with a zener across it to limit the charge
> to 100V?  Is this correct?

This is a very interesting point.  I would guess that the capacitor sits
in series with the secondary circuit between the current sense resistor
and the secondary coil, with a clamp zener in parallel.  

> 
> Aswell, any more info about high tension measurements?  How this
> would be done without frying everything in sight?
> 

Inductive pickups?  Standard part for many oscilliscopes.

> This ion gap stuff sure looks good.  I actually think it could be easier
> to do this (for us engineers/computer scientists) than it is to
> run all the sensors when retrofitting efi onto an old car.

Yes I agree.  It would be a bit easier than trying to retrofit a knock
sensor either to the block or under the spark plug.  (The sensor itself
is not the problem here but the associated signal processing and circuitry.)

Note that in a similar paper by researchers at Chrysler (SAE 950003), they
were able to process the signal with a simple integrator feeding into one
of the A/D ports on a HC11.  Misfire detection (in this case) was a trivial
task of reading the port and comparing the digital input to a threshold
near zero.

> 
> --rod.
> 
Robert 'it looks like it's time to convert to multiple coils' Dingli

PS The system won't work with leaded fuels.  :-(

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             Robert Dingli           r.dingli at ee.mu.oz.au

Power and Control Systems                 Thermodynamics Research Lab
Electrical Engineering                    Mechanical Engineering
   (+613) 344 7966                           (+613) 344 6728
  University of Melbourne, Parkville, 3052, Victoria, AUSTRALIA
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