[Gmecm] Tracker TBI Problems overcome!

[Steve Ravet]

> -----Original Message-----
> From: gmecm-bounces at diy-efi.org 
> [mailto:gmecm-bounces at diy-efi.org] On Behalf Of Cowen
> Sent: Thursday, February 08, 2007 2:18 PM
> To: gmecm at diy-efi.org
> Subject: [Gmecm] Tracker TBI Problems overcome!
> 
> Well!  Thanks for all your advice folks, but we were all wrong!
> 
> I got to be the Guinea pig trying out a brand new SnapOn 
> Mobis scanner on Tuesday, and it confirmed the
> O2 sensor is showing about 4 crosscounts at 2500 RPM.
> 
> At the same time, I rechecked the timing, shorting the check 
> connector etc.  It turns out it was somewhat advanced, so I 
> retarded the timing to stock.  The car ran worse than ever!  
> Ah ha!  Something I did had an effect!
> 
> On the way home, I advanced the timing repeatedly until I was 
> getting preignition under moderate load, then backed it off a 
> bit.  It now runs much better, appears to be getting good 
> mileage again, and passed AirCare.  In fact, the CO went from 
> 14.3g/km to 10.4g/km.  It still think I can just barely 
> percieve a bit of an "unsmoothness" under accel, but maybe 
> I'm paranoid.
> 
> So, I rechecked the timing.  It says it's about 26deg BTDC!  
> Supposed to be around 8deg.  I even tried a second timing 
> gun!  Apparently the timing mark no longer represents TDC.  I 
> can't imagine how that would be...

Probably the timing gauge hasn't moved, but maybe the timing mark on the
balancer has moved, if the rubber is worn out and the outer ring is
moving relative to the hub.  In that case the balancer probably needs to
be replaced.

If I can recap, it ran bad, then you cleaned up and replaced some
gaskets and it ran better for a while, then ran bad again.  If timing is
indeed the problem then it has been changing over time as you've been
working on it.  The mark moving is one thing, but the actual timing
changing is something else.  I'm not familiar with that engine, can you
describe how the ignition timing is done, where the pickups are, is it
distributor or ???  I'm not sure the problem is completely solved yet so
I'm still curious.

--steve