Mid-Year Engine Change Data

Engine Serial Number Location:

***UPDATED BY TSB #EF89004, DATED MAY 1989
GENERAL DESCRIPTION
During the 1989 model year, Nissan Motor Corp., made a mid-year engine change. The modifications improved vehicle driveability.
The following changes were made:
^ Engine compression ratio has been changed from 9.1 to 8.6.
^ An intake air temperature sensor has been added (including self-diagnosis for the circuit).
^ Enhancements to the electronic control unit.
^ Idle speed specifications.
^ Code 32 (EGR operation) diagnostic procedures.

ENGINE IDENTIFICATION
The change applies to all engines built AFTER engine number KA24-012039.
The engine serial number is stamped on the engine block, just below the #2 and #3 spark plugs.
All 1989 240SX models with an air temperature sensor in the air cleaner box have the newer (modified) engine.

DATA IDENTIFICATION
Throughout the Computers and Control Systems section, the following terms will be used to identify vehicles with and without the modification:
UP TO ENGINE KA24-012039 ... All vehicles built before and up to the modification.
AFTER ENGINE KA24-012039 ... All vehicles built after the modification.
If no designation of engine number is referenced, the information applies to both engines.