PROM Bugs

[Ludis Langens]

CSH-HQ wrote:
> 
> With the mention of code bugs, has anyone used one of the "fixed" codes, and
> was there much any difference?.
>   "Could" it just be a failsafe device, like the odd man "vote".
> If it affected emissions why would they let it not be cured?.
> An ego deal?.
> Maybe a legal "error" for a court fight?.

Recently, GM did recall most (all?) 1993 3.1 V6's because of an
emissions problem.  One of the PROMs where I found bugs is for the 93
DOHC 3.4.  It's very likely that the 3.1 and 3.4 use the same ECM with
the same program (but different calibration data).

The bug might not normally affect emissions.  The garbage data picked up
by the buggy functions may contain values that are "safe".  There might
be a measureable emissions failure only once the engine wears or sensor
values drift.  Even then, it might require a full emissions
certification process to detect.

The sad thing is - I've written a program that does 90% of the work to
find these bugs.  I haven't needed to read and understand every line of
code.  This does not say good things about GM QA.

PS, does anyone have a PROM dump for a '93 3.1?  I've got dumps for
older 2.8/3.1's, but nothing as new as '93.

-- 
Ludis Langens                               ludis (at) cruzers (dot) com
Mac, Fiero, & engine controller goodies:  http://www.cruzers.com/~ludis/