1981 DFI DIAGNOSTIC CODES, CODES 16,19,20 FAULTY CHIP

1981 CADILLACS EQUIPPED WITH V8-6-4 DIGITAL FUEL INJECTED ENGINES FOR NON-CALIFORNIA USE (FEDERAL EMISSIONS) HAVE FUEL METERING CONTROL CALIBRATIONS DURING COLD AND HOT-STARTING WHICH ARE NOT OPTIMUM FROM A DRIVEABILITY STANDPOINT FOR SOME VEHICLES. THIS CONDITION, DIAGNOSED AS A SAG OR HESITATION, IS MOST PREVALENT AFTER AN OVERNIGHT SOAK AT AMBIENT TEMPERATURES OF 50F-70F. ONCE THE ENGINE REACHES NORMAL OPERATING TEMPERATURE, THE SAG OR HESITATION IS NO LONGER EXPERIENCED . THE RELATIVE SEVERITY OF THIS CONDITION CAN VARY WITH AMBIENT TEMPERATURE, LENGTH OF TIME SINCE THE VEHICLE WAS LAST DRIVEN, AND INDIVIDUAL DRIVING HABITS. TO DIAGNOSE AND CORRECT THE ABOVE CONDITION, THE FOLLOWING PROCEDURE SHOULD BE USED: 1.INSPECT THE THERMAC AIR CLEANER OPERATION VERIFYING THE VACUUM SOURCE AND ALSO VALVE OPERATION. 2.VERIFY PROPER EGR SYSTEM OPERATION. THE VALVE SHOULD BE CLOSED AT COOLANT TEMPERATURES BELOW 130F (CODE 50 ON PARAMETER 4) AND AT IDLE ABOVE 130F. 3.VERIFY PROPER EFE OPERATION. THE VALVE SHOULD BE CLOSED BELOW COOLANT TEMPERATURE OF 120F (READOUT 45 OF PARAMETER 4)9 4.VERIFY ALL VACUUM HOSE ROUTINGS PER THE EMISSIONS LABEL. CHECK ELECTRICAL CONNECTORS FOR PROPER CONTACT. 5.VERIFY GENERAL SENSOR OUTPUTS USING PARAMETERICS. 6.CHECK FUEL PRESSURE. CORRECT THE CAUSE OF ANY INCORRECT PRESSURE FINDINGS PER SERVICE MANUAL PROCEDURES. 7.CHECK ENGINE BASE TIMING (GREEN CONNECTOR DISCONNECTED) AND RESET ONLY IF NECESSARY. VERIFY EST OPERATION (RECONNECT GREEN CONNECTOR AND CHECK TO SEE THAT ENGINE TIMING ADVANCES AT IDLE). 8.MEASURE MAP/BARO CORRELATION PER SERVICEMAN ARTICLE 81-43. CORRECT AS REQUIRED. 9.VERIFY ISC, TPS, AND MINIMUM AIR RATE PER SERVICEMAN BULLETIN 81-5A. 10.VERIFY INTAKE MANIFOLD GASKET INTEGRITY. CORRECT AS REQUIRED. 11.IF STEPS 1 THROUGH 10 HAVE NOT CORRECTED THE ABOVE CONDITION, INSTALL THE PROM SERVICE KIT LISTED BELOW. REFER TO SERVICEMAN BULLETIN 81-14 IF ADDITIONAL PROM AND ECM USAGE INFORMATION IS REQUIRED. IF STEPS 1 THROUGH 10 HAVE IMPROVED THE DRIVEABILITY TO AN ACCEPTABLE LEVEL, IT WILL NOT BE NECESSARY TO INSTALL THE NEW PROM'S. * ILLUSTRATION * ** SEE 82-8 FOR CALIF DFI **

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.