Engine - Spark Knock On Acceleration
90ford34 SPARK KNOCK - 4.9L EFI - WHILE ACCELERATING AT NEAR W.O.T. - VEHICLES BUILT FROM 7/24/89 THROUGH 3/18/90Article No. 90-21-12
LIGHT TRUCK: 1990 ECONOLINE
CALIBRATION: 0-52K-R00
WARNING: THIS MODIFICATION IS AUTHORIZED ONLY FOR THE LISTED ENGINE. PERFORMING THIS MODIFICATION ON OTHER ENGINE CALIBRATIONS IS UNAUTHORIZED AND COULD CREATE LIABILITY UNDER APPLICABLE FEDERAL OR LOCAL LAWS.
ISSUE: Moderate spark knock may be experienced while accelerating at near W.O.T. (0-5 HG. of vacuum) after the engine has reached normal operating temperature. This is caused by the EEC-IV processor strategy which results in a lean fuel mixture with too much spark.
ACTION: Install a new level EEC-IV processor with revised operating strategy. Refer to the following procedure for service details.
1. Check to be sure that the engine calibration is the one listed above.
2. Perform EEC IV Quick Test. Correct service code(s) as necessary.
3. Replace the existing EEC IV processor with EEC IV processor (F1TZ-12A650-ARA)
NOTE: THIS MODIFICATION WILL UPDATE THE ENGINE CALIBRATION FROM A 0-52K-R00 TO A 0-52K-R10 LEVEL.
Obtain an Authorized Modifications Decal and list the date, dealer number, and summary of alterations 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.
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Eligible Under Basic Warranty Coverage
OPERATION DESCRIPTION TIME
902112A Perform EEC IV Quick Test 0.5 Hr.
Only
902112B Test & Replace Processor 1.7 Hrs.
(Includes Mod. Decal & Perform Repeat Final Quick Test)
DEALER CODING
BASIC PART NO. CONDITION CODE
DRIVE M7
OASIS CODES: 632500