Autronic crank/cam timing problem? PT 2

[Carl Summers]

Hi,
    One other thing...I think I understand you correctly...but just to
clarify....The 60 degree is supposed to be on the cam so the Autronics only
sees one pulse and knows tdc compression stroke of #1 is near then the crank
trigger pulse fires the module(Autronic controlled) which fires the
coil.....Please forgive if I am wrong....most apps we use a distributor with
2 reluctors and pickups...one has one reluctor "window" for its pickup 60
degress from the other which has 8 "windows" for its pickup.....we have done
the crank trigger and if memory serves me this could be why you are having a
prob. HTH's
-Carl Summers


-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of clayb
Sent: Sunday, August 27, 2000 10:56 PM
To: diy_efi at diy-efi.org
Subject: Autronic crank/cam timing problem?



I can't fire my turbo 454 SMC. I've set the crank trigger at 60 BTDC
(give the ECU time to think),
and the cam pos sensor at 40 degrees BTDC. According to the timing
diagram, this should tell the ECU which of the 8 injectors, and 4
ignition coils to fire.

These timing settings were visual off the balancer, subject to 5 - 10
(being generous here)
degrees error. I varied cranking and idle ECU timing settings from 4
degrees to 32 degrees. I varied base fuel from 2 mS to 15 mS. I'm pretty
sure the ECU is controlling the fuel as instructed...

But, no joy. I've been getting the typical signs of firing on the wrong
cylinder or wrong timing (Boom!). I certainly know how to verify TDC and
timing. I set the ECU to negative edge for all ignition inputs/outputs,
and verified timing on crank and cam with a voltmeter switching from 5V
to 0V at the appropriate angle. I think I've eliminated the obvious, or
I wouldn't be writing.

One component I suspect, is the cam pos sensor. It's a Pertronix
trigger/coil driver (meant to retrofit the Mallory points distributor).
I attached a magnet to the old points cam lobe.  Triggers fine. I did
notice, however, that it does not seem to control "dwell angle" like I
would have thought. The output switches high when the cobalt-samarium
magnet is near, and low when it swings away. No one-shot or pulse width
control! Funny thing is, this is 40 - 50 degrees of rotation, on the
distributor, or 100 degs on the crank. Now, if negative edge triggered
is really that, well, it shouldn't matter a bit. Still one neg. edge at
the correct angle. Should I be concerned with the fact that the cam pos
line is high for more than one cylinder pulse? After all, if I had
toggled for pos. edge triggered timing inputs, the cam pos line would
have been low for more than 90 degrees of crank rotation.

I'm bringing the O-scope to bear on this tomorrow, but if you've got any
insights, please let me know

- Clay
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