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

[David Kase]

Definitely check the fuse by the ECU!  I replaced my CPS only to find that
fuse blown.  As DF mentioned - it was a shorted coil lead.

Kase

On Thu, Dec 31, 2009 at 7:08 PM, Paul Gailus <gailus at mindspring.com> 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
>
> -----Original Message-----
> >From: Konstantine Bogach <kbogach at comcast.net>
> >Sent: Dec 31, 2009 12:03 PM
> >To: s-car-list at audifans.com, forgied at shaw.ca
> >Subject: [s-cars] CMPS signal shape (was Location of CPS?)
> >
> >Ref:  UrS4 does not start.
> >I observed relative location (timing) of signals from CMPS (cam, I also
> >use Hall sensor term) and CKPS (crank) on my (running) 200tq and UrS4.
> >200tq has perfect timing - TDC pulse is right on the middle of the
> >negative pulse from Hall sensor, which is a rectangular pulse.  Bottom
> >of the negative pulse is not horizontal but the pulse still have
> >vertical front and tail (a better term should exist, I think).  The
> >ratio of pulse widths is 8-10 to 1 (CMPS to CKPS).  On S4 TDC this ratio
> >wa s 2-3:1.  This is just visually, I did not measure the width.
> >  But I can not call signal from S4's Hall sensor a rectangular pulse.
> >Here how it looked like:
> >
> >            |
> >              \
> >                   \
> >__                 \_________
> >   |      /
> >   |    /
> >   |  /
> >   |/
> >   A      B     C
> >
> >      ^ - location of the TDC pulse (betwee A and B) on S4.
> >
> >In 200tq the bottom of the negative pulse looked like this:
> >
> >            |
> >              \
> >                   \
> >__                 \_________
> >   |
> >   |
> >   |    _ --
> >   |_--
> >   A      B     C
> >        ^  - location of the TDC pulse
> >
> >|AB| would be different on these two pics (different scale).
> >I was expecting to see TDC signal not aligned with CMPS signal and this
> >would explain no start condition.  But looks like relative position of
> >the pulses is good, but I don't know if the signal produced by CMPS on
> >S4 is good.  Anyone has comments?
> >Also, anyone knows a source for fittings which can work with regular
> >fuel pressure gauge from a FLAP.  The set I have has no fitting for S4
> >(but I can use it on 200tq).   Maybe I don't have fuel pressure.  I can
> >hear that fuel pump works though.
> >
> >Konstantine
> >
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