Town Car V8-281 4.6L SOHC (1991)
Ignition Control Module: Customer Interest
Engine - Miss/Stumble/Rough Idle
Article No.
94-2-7
01/26/94
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IDLE - ROUGH - TOWN CARS BUILT FROM 8/1/90 THROUGH 11/30/92 AND GRAND MARQUIS/CROWN VICTORIA VEHICLES BUILT
FROM 1/1/91 THROUGH 12/31/91
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IGNITION SYSTEM - INTERMITTENT MISS, STUMBLE, ROUGH IDLE - TOWN CARS BUILT FROM 8/1/90 THROUGH 11/30/92 AND
GRAND MARQUIS/CROWN VICTORIA VEHICLES BUILT FROM 1/1/91 THROUGH 12/31/91
^
MISS - INTERMITTENT - TOWN CARS BUILT FROM 8/1/90 THROUGH 11/30/92 AND GRAND MARQUIS/CROWN VICTORIA
VEHICLES BUILT FROM 1/1/91 THROUGH 12/31/91
^
STUMBLE - TOWN CARS BUILT FROM 8/1/90 THROUGH 11/30/92 AND GRAND MARQUIS/CROWN VICTORIA VEHICLES BUILT
FROM 1/1/91 THROUGH 12/31/91
FORD:
1992 CROWN VICTORIA
LINCOLN-MERCURY:
1991-92 TOWN CAR
1992 GRAND MARQUIS
ISSUE:
Intermittent miss, stumble or poor idle quality when engine speed is less than 1000 RPM may be due to inadequate fuel distribution.
ACTION:
Confirm that ignition system connections are properly installed and perform normal diagnostics to be sure no other fault is present. If a misfire fault is
found and all components check OK, replace the Ignition Control Module (ICM) with a new improved part. The new ICM has a repetitive spark
calibration. This feature allows the spark plugs to fire multiple times when engine speed is under 1000 RPM, resulting in improved idle quality. Refer to
the following procedure and to the Service Manual, Section 03-07, for service details.
NOTE:
PERFORMANCE OF THIS PROCEDURE REQUIRES THE USE OF THE SERVICE BAY DIAGNOSTIC SYSTEM CART (SBDS) FOR BEST
RESULTS.
1. Verify concern by performing an SBDS Power Balance Test with the vehicle idling in Drive.
NOTE:
IF SBDS IS NOT AVAILABLE, VERIFY THERE ARE NO SPARK PLUG OR SPARK PLUG WIRE FAILURES BY USING A NEON BULB
SPARK TESTER OR AN AIR-GAP SPARK TESTER.
