[Gmecm] RE: Tracker TBI problems

[Eck, Joel GCC ISS Engineer]

My personal experience with #5 - 90 civic with 1500 or 1600 engine - cam
off 1 tooth either direction still ran pretty well. One direction, it
became a bunch torquier (I know, not a real word) but had some ping
problems; the other direction, it idled a little rough, but otherwise
ran pretty good. It depends  on how many teeth the cam gear has, as that
will translate to how many degrees off the cam will be if it is off by
one tooth.

In regards to #8 - True enough, that would not have caused the timing to
shift all on its own, but it would have caused the timing to be set
incorrectly in the past, say, before the problem was known. If the outer
ring of the balancer is shifting each and every time the engine is run,
then you can never get an accurate reading, because it will always be
off by some unknown value. May be worth your while to just tear into it
and check it out. If nothing else, it can then be eliminated as a
contributing factor.

It's been while since the problem was first mentioned, but was the
timing adjusted before the faulty TBI gaskets were discovered? Perhaps
the timing was fine previously, and then adjusted to what appeared to be
good. The problem didn't go away, bad gaskets were replaced, but then
the incorrect timing lived on beyond the original cause of the problem??
Just a thought..

Thanks,
Joel


-----Original Message-----
From: gmecm-bounces at diy-efi.org [mailto:gmecm-bounces at diy-efi.org] On
Behalf Of gmecm-request at diy-efi.org
Sent: Saturday, February 10, 2007 12:22
To: gmecm at diy-efi.org
Subject: Gmecm Digest, Vol 24, Issue 10

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