[Gmecm] Tracker TBI problems

[Mark Riley]

I would wonder if it has chewed out the keyway on the crank sprocket to
allow the cam and timing to advance and retard. Have seen it happen on 1.5l
Mitsubishi engines in Hyundai's. Like to drove me to drink till I saw the
timing change with just a rev up of the engine. Then checked the cam timing
and it was off where it had been correct earlier that day. Powered medal
crank sprocket wasn't hard enough and would kinda go away.

Mark

-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On Behalf
Of Cowen
Sent: Friday, February 09, 2007 5:14 PM
To: Gmecm at diy-efi.org
Subject: [Gmecm] Tracker TBI problems

I'll answer as many questions as I can from the posts:

1.  Yes, has a dizzy, but no mechanical or vacuum
advance.
2.  Has a "cam Position Sensor" inside dizzy, no Crank
Position Sensor.
3.  I've swapped in another "known good" dizzy, no
changes good or bad.
4.  Has a timing belt, I changed it about 4 years ago.
 No other engine work of any kind done/needed.
5.  Haven't checked cam timing, but would it really
run as well as it does if it had jumped a tooth?  I
thought of this early on, but discarded the idea as
unlikely.  Maybe I should tear it apart and look!  If
I think it through though, that would not explain
timing problem, because strobe would still flash
around the correct TDC mark (because dizzy can be
adjusted independantly of cam).
6.  Yes Steve it did seem to run well after a pile of
work, but it was for only a few days.  Still, strange
that the problem shows variability.
7.  Crank pully is bolted to crank, 4 small bolts. 
Keyed too?  Don't remember.
8.  Even if harmonic balancer had shifted, there are
no sensors there, so that cannot change timing - only
position of timing mark.  Therefore, could not have
causes this problem, only made it more confusing to
fix (as timing appears different than it is).

Thanks again for the ideas, and now I'm really
wondering about the cam jumping a tooth somehow!!

Duncan

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