1984 PORT FUEL INJECTION ECM REPLACE INFORMATION

Models Affected: All 1984 3.8L MFI & SFI and 2.0L EFI Equipped Vehicles

The all new ECM used on 3.8L Buick MFI and SFI engines uses a plug in Prom and Calpac. In appearance the Prom is basically the same that has been used on CCC and EFI vehicles in the past. The second plug-in module used in this ECM is called a Calpac and is smaller than the PROM. Calpac is programmed to take over basic fuel and spark control functions in the event of an ECM or Prom failure. Stated simply it allows continued engine operation in the back-up mode.

Anytime an ECM replacement is required on a Buick 3.8L MFI or SFI or a 2.0L EFI engine both the Prom and Calpac must by removed from the replaced ECM and installed into the replacement ECM.

See illustrations for location of Prom and Calpac.

Mote: If the Calpac is left out of the 3.8L Buick engines, the engine will start and run, however a solid "service engine soon" lamp will appear along with a code 52 (missing Calpac) will be stored.

If the Calpac is left out or a 2.0L EFI engine, the engine will crank but will not run. It will nor provide a "service engine soon" lamp and will not store code 52.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.