92 Merc bucking

[fuba]

My MGM is still bucking when I lightly step on the gas. It idle's fine and won't buck if I get on the gas. I replaced the MAF and the TP-sensor. The check engine light is not comming on.

What could be going on?

[Stevo2]

Originally Posted by fuba

My MGM is still bucking when I lightly step on the gas. It idle's fine and won't buck if I get on the gas. I replaced the MAF and the TP-sensor. The check engine light is not comming on.

What could be going on?

Plugs, wires or if you still have the original Ignition Control Module you may want to replace that but they are expensive.



Engine - Miss/Stumble/Rough Idle
Article No.
94-2-7

01/26/94

^ 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

^ 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.

2. Observe the test for ten (10) minutes to determine which cylinder(s) are "missing". Refer to Figure 1 for a typical pattern of a cylinder misfire.

3. Verify that all spark plugs and spark plug wires are functioning properly; replace as required.

4. After confirming that there are no component failures, replace the ICM with an improved part (F2PZ-12K072-A) this old part number has been superceded.


Connector, DIS Ignition Revised
ARTICLE NO.
95-10-2

05/22/95

^ IGNITION CONTROL MODULE (ICM) - REVISED CONNECTOR RETENTION CLIP AND SEAL - DISTRIBUTORLESS IGNITION SYSTEMS (DIS) ONLY

^ LAMP - "MALFUNCTION INDICATOR LAMP" (MIL) ILLUNINATED - REVISED IGNITION CONTROL MODULE (ICM) CONNECTOR RETENTION CLIP AND SEAL - DISTRIBUTORLESS IGNITION SYSTEM (DIS) ONLY

^ WIRING - REVISED IGNITION CONTROL MODULE (ICM) CONNECTOR RETENTION - DUSTRUBUTORLESS IGNITION SYSTEM (DIS) ONLY

FORD:
1991-94 ESCORT
1992-94 CROWN VICTORIA
1993-94 TAURUS
1994 MUSTANG, THUNDERBIRD

LINCOLN-MERCURY:
1990-94 TOWN CAR
1991-94 TRACER
1992-94 GRAND MARQUIS
1993-94 MARK VIII
1994 COUGAR

LIGHT TRUCK:
1990-94 AEROSTAR, RANGER
1991-94 EXPLORER

ISSUE:
Some vehicles may have a disconnect of the Ignition Control Module (ICM) connector or moisture buildup within the connector. This can cause hard to start/no start, rough idle, or "check engine light" illumination concerns. The improved gasket and connector retainer that are currently used in production are now available for service of prior model distributorless ignition systems.

ACTION:
Install new Connector Sleeve Retainer Clip and a current production seal (gasket). The clip assembles in between the connector beams and the ICM which will prevent accidental disconnects. The new seal is a "solid silicone" gasket that provides improved resistance to moisture entry into the connector. Refer to the ICM Connector Harness Wire Service kit (F5CZ-14A411-AA) for service details (I.S. 6621).

AFFECTED ENGINES

^ Escort/Tracer - 1.9L
^ Crown Victoria/Grand Marquis/Town Car/Mark VIII- 4.6L
^ Taurus Flex Fuel, California - 3.0L
^ Mustang - 3.8L
^ Thunderbird/Cougar - 3.8L SC, 3.8L California only, and 4.6L
^ Aerostar/Explorer/Ranger - 4.0L


The Ignition Control Module (ICM) Connector

Harness Wire Service Kit (F5CZ-14A411-AA) contains the following components:

^ One (1) Gasket - Wire Seal
^ One (1) Retainer - Wire Connector Sleeve (Clip)
^ One (1) Instruction Sheet (I.S. 6621)


PART NUMBER PART NAME

F5CZ-14A411-AA ICM Connector Harness Wire Service Kit

OTHER APPLICABLE ARTICLES: NONE

WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage For 1992-94 Model Years, Basic Or Emissions

[master hec0]

i got the bucking thing it will skip a beat and will buck every 3 months for 20mins or so then it will go fine again its weird but wen the buck happenns the cel light goes on for me

[fuba]

Could a bad oxygen sensor cause this type of problem?

[Stevo2]

Originally Posted by fuba

Could a bad oxygen sensor cause this type of problem?

They could but is the rest of the ignition system in good shape?
Any codes in the computer?
O2 sensors are recommended to be replaced every 100K.
My 91 GM had bad plug wires from the factory, there was eventually a Service Bulletin on it. The bucking problem started out very intermittent. The NAPA wires have been on for 10 years now with no problems.

[vtwindave]

had same problem with 95 gm, changed plug wires & problem went away