Timing jump at idle

[Edmond]

Mine does the same thing. Jumps from like 16-17 to 23-24 every 1/2 second or
so. I did catch it ONE time when it was stable around 16 degrees.  Is the
timing table pretty smooth when  jumping from one rpm setting to anther ?
Say at 600RPM and 30kpa you have 16 degrees and at 700 RPM you have 20
degrees. That would probably cause it to jump that way...   Just a
hypothesis.


----- Original Message -----
From: "Bob Valentine" <bob at tecmark.com>
To: <gmecm at diy-efi.org>
Sent: Friday, November 10, 2000 2:32 PM
Subject: Timing jump at idle


> I'm trying to figure out why my timing varies +/- about 4 degrees.    I've
> flattened the table for several cells around in gear idle, 625rpm.  MAP
> stays rock-steady at 35kpa.    Injector pw varies from 2.55-2.6ms.  The
> idle is reasonably smooth no surging or misfire, but would be smoother
with
> the timing stable.
>
> With the timing connector pulled and a timing light on the crank, the mark
> stays even on 6deg.   The mark moves and follows the scantool with the EST
> hooked up.  I changed the distributor (and module) since the one in the
> motor had a slight bit of end play - no difference, same symptoms.   Plug
> wires are routed as far from the harness as possible.    Disconnected the
> alternator to rule out AC noise, no difference.
>
> Is this "normal" or is something going on?
>
> -> Bob Valentine
> -> bob at tecmark.com
>
> --------------------------------------------------------------------------
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