[Gmecm] 1226867 Calibration Change

[RogeranCarol]

Les:
It's quite possible your Firenza is an export model that was intended to
run on leaded gas; consequently, your EPROM is programmed to operate
in open loop only. I believe the spark tables are quite different than those in
an ECM running in closed loop mode. Look at your car's production sheet
to determine if this is so. As an example, RPO code NM9 would indicate
"export, Canada, leaded fuel". I also believe you could simply change your
EPROM to one intended to run in closed loop. I think Broad Cast Code HTM
(part number 16054815) would work. My data indicates it is for a 2.0L with
3-spd auto THM 125 clutch, California Emissions.
Roger
  ----- Original Message ----- 
  From: Les 
  To: gmecm at diy-efi.org 
  Sent: Saturday, June 18, 2005 9:23 PM
  Subject: [Gmecm] 1226867 Calibration Change


  Hi all,

  I just stumbled across your forum while browsing for information about GM ECM's. This seems to be a goldmine of information on the subject I'm checking out.

  I just picked up a 1985 Firenza S in great shape and have been learning how the ECM operates (extreme rookie here). This Firenza has the OHV 2.0L TBI "P" with AT and it seems to be running rich all the time. I did some checks and have discovered that it never goes closed-loop and then on further investigation found out to my surprise that it doesn't have an O2 sensor. I looked at the build codes and discovered that it was built to this specification, i.e. non-closed loop operation. It has all the wiring for an O2 sensor so I'm wandering if it's possible to get this to run closed-loop if I install an O2 sensor along with a change in calibration? The ECM is a 1226867 with a 16041334 EPROM and a memory chip #HDP2636. 

  Would appreciate any comments/thoughts/suggestions anyone has. 

  Thanks,
  Les


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