[s-cars] CMPS signal shape (was Location of CPS?)

[Konstantine Bogach]

Hi Paul,  yes, it was AC coupling.  Coupling fell in the gap in my 
understanding of this instrument.   I cranked both cars but 200tq was 
hot which may explain difference in pulse width.
I will look into possible short in coil and will check +12V.
Yesterday I noticed that there is no spark.  And then some time later 
there was a spark.   I observed actual plug.
I got a wealth of advices and info from the list and need to digest it 
before planning next "space walk"   at 28 F.

On 12/31/2009 07:08 PM, Paul Gailus wrote:
> Konstantine,
>
> If you had AC coupling selected on your 'scope instead of DC coupling, that could explain the upward slope you're seeing on the bottom of the negative pulse from the Hall sensor. It would also explain the downward slope at the end of the pulse.
> Was the 200tq engine running (instead of cranking) when you took the measurement?  I suspect the engine was running based on your comment about a "different scale".  A shorter pulse duration with the engine running would explain why the pulse appeared to be flatter on the bottom (less time for it to ramp up).
>
> Anyway, back to the real problem at hand. I agree that the relative timing of the sensor outputs looks good, so you should probably focus on the fuel system. Before you leave the ignition though, make sure you've got a consistent 12 volts to the coils. I had an intermittent short in a coil of my urS4 that would trip the thermal breaker. The breaker would sometimes reset long enough to let the engine catch and run for a very short time.
>
> Paul
>