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Test KP - Octane Adjust

NOTE: Enter this test when directed here by a driveability symptom. This test is intended to diagnose only the following systems or components:
  • Harness circuits (VPWR, SIG RTN, OCT ADJ)
  • Octane shorting bar connector
Fig 1: Octane Adjust Circuit
G90D13154
OCTANE ADJUST SHORTING BAR LOCATIONS

Application Location
MA PFI (Car) Near EEC power relay, fuel pump relay and ECA, in passenger compartment.
TEST PIN WIRE COLOR IDENTIFICATION

Application (Test Pin No.) Wire Color
Pins 18, 43 or 44 (OCT ADJ) (MA PFI) Green/White
Pin 46
MA PFI Light Green/Black
All Others Black/White

The purpose of the Octane Adjust Shorting Bar is to provide optimum spark advance for the fuel being used. If the vehicle engine detonates (spark knock), REMOVE the Octane Shorting Bar. This retards spark advance about 3 to 4 degrees. If the vehicle continues to detonate, use fuel with a higher octane rating.