Engine - Spark Knock/Detonation During Acceleration
Article No.98-10-1
05/26/98
^ DETONATION - DURING ACCELERATION -
VEHICLES BUILT THROUGH 8/97
NOISE - SPARK KNOCK DURING ACCELERATION -
VEHICLES BUILT THROUGH 8/97
FORD:
1996-97 CROWN VICTORIA
LINCOLN-MERCURY:
1996-97 GRAND MARQUIS, TOWN CAR
This TSB article is being republished in its entirety to update the Service Procedure.
CALIBRATION
6-18E-R05-R11, 6-18F-R05-R11, 6-18H-R05-R11, 6-18I-R05-R12, 6-18J-R05-R11, 6-18M-R05-R11, 6-18N-R05-R11, 6-18Q-R05-R11 6-18S-R05-R11, 7-18E-R10, 7-18F-R05-R10, 7-18H-R05-R10, 7-18I-R05-R11, 7-18J-R10, 7-18M-R05-R10, 7-18N-R05-R10, 7-18Q-R10, 7-18S-R10
WARNING
THIS MODIFICATION IS AUTHORIZED ONLY FOR
THE LISTED ENGINE(S). PERFORMING THIS MODIFICATION ON OTHER ENGINE CALIBRATIONS IS UNAUTHORIZED AND COULD CREATE LIABILITY UNDER APPLICABLE FEDERAL OR LOCAL LAWS.
All prior calibration revision levels to the calibrations listed above are also included in this TSB.
ISSUE
Some vehicles may experience detonation during acceleration. This may be caused by contamination of the Mass Air Flow (MAF) sensor which then misinterprets the barometric pressure resulting in a leaner than desired condition.
ACTION
Replace the MAF sensor and reprogram the Powertrain Control Module (PCM). The sensor has been revised to reduce the possibility of contamination and reduce the possibility of spark knock. Refer to the following text and PCM Cross Reference Chart for details.
If detonation occurs during moderate to wide open throttle, check the following parameters.
NOTE
THE VEHICLE SHOULD BE STABILIZED AT NORMAL OPERATING TEMPERATURE (ENGINE COOLANT TEMPERATURE GREATER THAN 88°C/190°F), THE TRANSMISSION SHOULD BE IN PARK/NEUTRAL POSITION WITH THE AIR CONDITIONING OFF. THE ENGINE SHOULD ALSO BE IN CLOSED LOOP OPERATION (VERIFIED BY LOOKING AT THE "LOOP" PARAMETER IDENTIFICATION DISPLAY (PID) ON THE NEW GENERATION STAR (NGS) TESTER).
1. Check it barometric pressure sensor output is below 150 Hz. This can be accomplished by using the NGS Tester and by calling up the PID called "BARO" or "BP" depending which level of NGS software is being used.
2. Check if the MAF sensor voltage (NGS PID "MAF V") is greater than 1.05 volts.
3. Check if the long term fuel trim (NGS PID "LONGT1" and "LONGT2") is less than -10%. If two or more of the above conditions are met, perform the following:
Disconnect the MAF sensor hardshell connector. Cycle the ignition key twice and drive the vehicle until the Malfunction Indicator Lamp (MIL) is illuminated. Verify that the "BP" has gone to 157 Hz (default Failure Mode Effects Management (FMEM) value) and try to duplicate detonation concern.
^ It the detonation is eliminated, replace the MAF sensor.
NOTE
PCM REPLACEMENT IS NOT AUTHORIZED BY THIS TSB. REFER TO THE POWERTRAIN CONTROL/EMISSIONS DIAGNOSIS (PC/ED) SERVICE MANUAL FOR APPROPRIATE DIAGNOSTIC PROCEDURES IF PCM HARDWARE PROBLEMS EXIST.
For vehicles that exhibit detonation during 3rd gear with the torque converter at approximately 50% lockup, 35-48 km/h (22-30 mph), light throttle, the PCM will have to be reprogrammed to the latest level. Check the emissions decal to verify the vehicle does not have the latest level calibration. Reprogram the PCM to the latest level using Service Bay Diagnostic System (SBDS) or NGS Tester and the September CD-ROM. Refer to the following PCM Application Chart for the correct PCM.
If neither of the above resolves the concern, remove the octane adjust shorting bar and redrive the vehicle to verify the concern has been eliminated.
Obtain an Authorized Modification Decal (FPS 8262 - obtainable through DOES II, 25/pkg) and list the date, dealer number, and summary of modifications performed. Select a prominent place adjacent to the Vehicle Emission Control Information Decal suitable for installing the Authorized Modifications Decal. Clean the area, install the decal, and cover it with a clear plastic decal shield.
PART NUMBER PART NAME
F6ZZ-12B579-AA Mass Air Flow (MAF) Sensor
OTHER APPLICABLE ARTICLES: NONE
SUPERSEDES: 97-24-11
WARRANTY STATUS: Eligible Under The Provisions Of Bumper To Bumper Warranty Coverage And Emissions Warranty Coverage
OPERATION DESCRIPTION TIME
981001A Replace Mass Air Flow 0.3 Hr.
(MAF) Sensor
981001B Reprogram Powertrain 0.6 Hr.
Control Module (PCM)
DEALER CODING
CONDITION
BASIC PART NO. CODE
12B579 49
OASIS CODES: 497000, 615000, 615500