Skyhawk L4-121 2.0L VIN K TBI (1987)
PROM - Programmable Read Only Memory: All Technical Service Bulletins
Engine Turbocharger - Erratic/Overboost Operation
Bulletin:
87-6-23
Date:
Feb. '88
Ref. No.:
87-220-6
Corp. Ref. No.: 736529
SUBJECT:
ERRATIC TURBO AND TURBO OVERBOOST OPERATION
MODELS AFFECTED: 1987 SKYHAWKS WITH THE 2.0L OHC TURBO ENGINE (VIN CODE M) AND AUTOMATIC TRANSAXLE
Some 1987 turbo Skyhawks may experience erratic turbo operation due to two known conditions:
Condition 1:
Under wide-open throttle operation and at the 2-3 upshift on an automatic transmission, a temporary turbo overboost can occur. A Code 31 "SERVICE
ENGINE SOON" light may be triggered if overboost lasts too long. For the above specific driving overboost condition, the following PROM will correct
the condition.
Transaxle
PROM Part Number
Automatic
16084410
To ensure completeness of the repair, refer to the Code 31 diagnostic section and check other possible causes of Code 31.
Condition 2:
Erratic turbo boost operation can also be caused by the boost solenoid sticking or oil plugged lines (refer to Code 31 diagnostics in the service manual).
During engine operation, engine oil can deposit inside the boost solenoid lines and/or wastegate pressure line vent at the wastegate solenoid.
If the wastegate solenoids foam air vent is oil soaked, then replace the solenoid assembly. In addition, the wastegate-to-solenoid pressure line should be
disconnected at both ends and blown clear. The wastegate solenoid-to-throttle body vacuum line should also be disconnected at the solenoid end and
blown clear toward the throttle body. This line cleaning prevents turbo overboost from recurring and solenoid valve failure.
WARRANTY INFORMATION
Use applicable Labor Time and Number.
