Century Estate Wagon L4-151 2.5L VIN R TBI (1987)
PROM - Programmable Read Only Memory: Customer Interest
Engine - Hard Start When Hot or Knock
Bulletin 88-6E-11
Date April, '88
File. No. 83-130-6E
Corp. Ref. No. 8363O4R
SUBJECT:
HARD START (LONG CRANKING TIME/ENGINE FAILS TO RUN)
WHEN HOT AND/OR DETONATION (SPARK KNOCK)
MODELS AFFECTED:
1987-88 CENTURYS WITH LR8 2.5L L-4 ENGINES (VIN CODE R)
1987 SOMERSETS/SKYLARKS WITH L68 2.5L L-4
ENGINES (VIN CODE U)
Some of the above vehicles equipped with the 2.5L engine may experience two driveability conditions. The conditions are (1) extended cranking
times/engine fails to run when the engine is hot, and (2) spark knock (detonation).
The repairs outlined in this bulletin should be made only if standard diagnostics outlined in the service manual do not correct the condition(s).
SPARK KNOCK (DETONATION)
An ECM calibration change is available to retard the spark advance when the engine is operating in moderate load conditions between 1800 and 2800
engine RPM. An example of this condition is spark knock observed while negotiating a moderate grade when cruising at 55-65 mph. The service
PROMS listed in Table 2 should be installed to correct this condition.
WARRANTY INFORMATION
Labor Operation Number: T1316
Labor Time:
.4 Hours
Trouble Code:
92
HOT ENGINE STARTABILITY (Long Cranking Time/Stalling When Hot)
Conditions experienced when starting a hot engine, e.g. extended cranking times/engine fails to run can be repaired by installing the components shown
in Table 1. The conditions may be caused by vaporizing of the fuel in the fuel lines and throttle body injector assembly (TBIA) under hot conditions.
NOTICE:
IT IS MANDATORY TO CHANGE THE ECM CALIBRATION PROM IN CONJUNCTION WITH THE FUEL PUMP.
The fuel pumps listed in Table 1 deliver far more fuel at low system voltages than the original fuel pump and will result in irregularities when starting the
engine in cold weather. To avoid these irregularities, the ECM PROM must be changed along with the fuel pump.
Instructions detailing assembly of the fuel pump, fuel sender, and pulsator are included with the fuel pump. In an effort to reduce the number of service
packages, the retarding of the spark advance has been incorporated into this ECM calibration. This calibration will correct the hot engine starting
irregularities with no observed change in powertrain performance because of the spark advance change.
WARRANTY INFORMATION
Labor Operation Number: T1314
Labor Time:
1.6 hours - Century
1.7 hours - Somerset/Skylark
Trouble Code:
92
BOTH HOT ENGINE STARTABILITY AND SPARK KNOCK
The combination of these conditions can be corrected by installing the components listed in Table 1.
WARRANTY INFORMATION
Labor Operation Number: T1314
