Mirage Sedan LS L4-1834cc 1.8L SOHC MFI (1999)
PROM - Programmable Read Only Memory: All Technical Service Bulletins
PCM - DTC P0120 TP/Engine Surge/Sag
NO: TSB-99-13-007
DATE: October, 1999
MODEL: 1998-99 Mirage
SUBJECT:
PCM REPROGRAMMING FOR ENGINE SURGE/COLD START/DTC P0120
PURPOSE
Some affected vehicles may experience engine surge at 45-50 mph and/or engine sag during cold start. This may be caused by incorrect powertrain
control module (PCM) software parameters resulting in incorrect EGR and air/fuel ratio (but does not affect emission levels). The PCM may also cause
the "SERVICE ENGINE SOON" light to come and set Diagnostic Trouble Code P0120. Reprogramming the PCM as described in this bulletin will
eliminate these conditions.
However, it is very important to check other vehicle conditions that may affect engine performance before reprogramming the PCM.
AFFECTED VEHICLES
1998-99 Mirage models
PROCEDURE
1.
Verify that the base idle speed is within the standard value. Deposits in the throttle valve may affect engine performance. Refer to "Basic Idle
Speed Adjustment" in Group 13 of the appropriate Mirage service manual.
2.
Perform the appropriate inspection procedures as needed:
^
For hesitation, sag or stumble, refer to Inspection Procedure 15 in Group 13 of the appropriate Mirage service manual.
^
For engine surge, refer to Inspection Procedure 19 in Group 13 of the appropriate Mirage service manual.
! CAUTION
BATTERY VOLTAGE (AS MEASURED AT THE BATTERY POSTS WITHOUT ELECTRICAL LOAD) MUST BE 12.4V OR HIGHER IN
ORDER TO REPROGRAM THE PCM.
3.
Using the MUT-II scan tool, record any DTCs set in the PCM. If any DTC except DTC P0120 is set, follow the appropriate DTC troubleshooting
and repair instructions in the service manual. Then go to Step 4.
4.
Use the MUT-II to erase all DTCs set in the PCM.
5.
Gather the following reprogramming equipment:
6.
Turn the ignition key to OFF and disconnect the MUT-II.
7.
Install the red label interface cartridge to the MUT-II. Then install the red memory card and the red label ROM pack. Be sure to use the Mirage
ROM pack (Database No. RN99081).
8.
Connect the MUT-II to the vehicle. Connect BOTH the 16-pin and the 12-pin data link connectors. (Some 1999 models may have the 16-pin
connector taped up to the harness.)
9.
Turn the ignition key to ON.
! CAUTION
DO NOT DISTURB THE HARNESS CABLES OR CONNECTIONS. INTERRUPTION DURING THE PROGRAMMING PROCESS COULD
CAUSE THE PCM TO LOSE DATA OR PREVENT FUTURE PCM REPROGRAMMING.
