[Diy_efi] RE: EPROM damage?

[David Daniel]

David Daniel wrote:
>
> What really has me baffled is the fact that, with the
> factory ECM and the replacement ECM, the SES light stays on the entire
time
> the engine is running, but only flashes a code 12 when I jump the ALDL
> connector, and I get no response from the TPS.

A bad EPROM should show up as a code 51.

It is odd that SES stays on but you can't pull any real error codes.
Hmmm, I wonder if the ECM is somehow stuck in limp-home mode.  The
surging idle and no TPS response also suggest that.  You don't perhaps
have a 3.9K resistor across ALDL pins A and B?

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

Ludis,
I do not have any type of resistor jumped across pins A & B in the ALDL.  I
was using a "high-tech" paper clip to pull the codes.  Limp-in mode crossed
my mind, too, but I've never experienced a car doing that before.  I'll
check resistance across those pins and see what I find.

I did swap in an ECM from a '87 S-10 Blazer (2.8 TBI, 700r4)(#1227429  ARW)
today.  It made a world of difference.  It runs ALMOST as well as the
factory ECM did before the engine swap.  The only issue I have with that
setup is that it has a slight stumble when it returns to idle from higher
RPM's.  I've only run it in the garage, so I can't tell how it would react
while driving.  The SES light goes out once the engine starts, just like it
is supposed to do.

This is making me lean towards the re-man ECM or my EPROM being the culprits
here.

Thanks for the info,

Dave D.


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