Tuning Eproms (was ECM 1228746 Help)

[Bruce Plecan]

> <<  found this ECM #1228746 in Ludis's site and it is listed as using the
> same circuit
>  board as the 1227747 ECM. I also found a bin file for it in the DIY
incoming
>  ftp. But I can't find the pinout diagram. Does it use the same pinout as
the
>  7747 if it has the same circuit board? >>

> Anyone?

Some times when all else fails you have to go to the library and hunt
around, or buy a manual with the info you need.

> Also, disconnected my O2 the other day and drove around to see how "off"
my
> EPROM was. The voltage on the disconnected O2 was never below 0.7 volts
and
> sometimes up to 0.9 volts. And this was without resetting the BLMs back to
> 128. I bet if I take power from the ECM and do this again, it may not run
at
> all. Any comments?

Just disconnecting the O2 is point less.
That just puts the ecm in a *limp home* mode.
You need to set the C/L CTS Temo enable to a higher then reachable level.
Then for grins disable the codes 13 44 45
Then see what you have.

> Also, concerning tuning EPROMS. I can see why you would want to tune the
fuel
> to get the BLMs to 128. You are basically getting the mixture right on to
> where the O2 is a redundant sensor. But the timing seems to be a different
> situation. Since there is no timing equivalent of the BLM (other than the
> knock retard safety device), is it possible that GM sets the timing where
it
> is to minimize emissions such as NOx at part throttle?

GM has dozens of calibration considerations.  That's why they can be such a
trade of.

 Maybe do-it-yourself
> tuners should concentrate on timing at WOT only since its a free for all
> there, i,e, emissions be damned. Or do I have too much faith in GM's
talents?

Tuning wise, the only person, that can keep me happy is me.
I know what I like.  I know how to measure the perforance that I'm
interested in, and have the patience, time, effort and energy to get what I
want.  I take every advantage of what GM allows me to do WHEN necessary.   I
don't get into areas of the prom that I don't need to, just for ego things.
I do what is necessary, and leave the rest alone.
I'll bet ya dolllars to donuts, that some of the stuff I've done is much
cleaner then the oem stuff.  But, some of the off road usage stuff is dirty
is some areas.
The oem has to work with 30K to 100K mile plug change intervals, I never
reach a 1/3 of their min time.

> Are you DIY tuners changing timing strictly to get the most performance
out
> of your engines and discarding emissions concerns, or are you saying GM is
> doing a half arsed job in both timing and fuel?

Reread the above
Grumpy



----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org