Powertrain Control Module - Surge on Light Engine Load
Bulletin No.: 015/96Issued: 06/27/96
Revised:
Category
F
Applicable Model/s
1994 B2300
Subject:
ENGINE SURGE UNDER LIGHT ENGINE LOAD (High Ambient Temperature and Humidity)
APPLICABLE MODELS
1994 B2300 with a manual transmission and calibration code of 4-49U-R05, 4-49U-R10, 4-491-R10 or 4-49T-R00.
NOTE:
^ This repair is ONLY authorized for the above vehicles and calibration numbers. Performing this repair on vehicles other than the above may violate state and federal laws.
^ This repair is not authorized for vehicles with a 4.10 axle ratio for 4WD.
DESCRIPTION
An engine surge may occur at cruising speeds [40 - 65 MPH (70 105 km/h)] during slight acceleration in high ambient temperatures and high humidity. This concern may be caused by erratic combustion from excess exhaust gas from the Exhaust Gas Recirculator (EGR).
Customers complaining of this concern should have the vehicle inspected and a revised Powertrain Control Module (PCM) installed to reduce EGR flow, if necessary.
REPAIR PROCEDURE
1. Verify the complaint in temperatures above 85 degrees F (30 degrees C).
2. Verify that the calibration number is 4-49U-R05 or 449U-R10.
NOTE:
Calibration Label is attached to the driver's side "B" pillar.
3. Verify that the Engineering P/N is not F4PF-12A650-UB.
NOTE:
The Engineering P/N is located just below the bar code label on the PCM connection.
^ If the vehicle has the above symptoms, does not have F4PF-12A650-UB, and has the calibration code listed above, proceed to step 4.
NOTE:
Verify that the Engineering P/N F4PF-12A650-MA or UA is on the PCM. Vehicles with these PCMs have an updated calibration of 449T-R10 or 4-49T-R00. Even if the vehicle has one of these calibration codes, it is still necessary to proceed to step 4.
^ If the vehicle has the above symptoms but does not have the calibration code listed above, refer to the workshop manual, section F for troubleshooting and repair information.
4. Perform normal diagnostic procedures. Refer to the workshop manual, Section F.
^ If any DTCs are detected, repair the vehicle as necessary.
5. If the concern is still present, deactivate the EGR.
^ If the concern is eliminated, install PCM (F4PF-12A650-UB).
NOTE:
If the vehicle has a calibration code of 4-49U-R05 and the PCM does not have an Engineering P/N of F4PF-12A650-MA or F4P F-12A650-UA, the idle Air Control motor (IAC) must be replaced with a new level part.
6. Perform all diagnostic procedures and verify that no DTCs are present.
7. Confirm that the surge is reduced.
8. List the date, dealer number, alteration performed and the Service Bulletin number on the Authorized Modification decal.
9. Clean the area near the Emission Control information label and affix the Authorized Modification decal.
10. Cover the decal with plastic shield.
NOTE:
This information advises technicians of the PCM changes if future repairs are necessary.
PARTS INFORMATION
WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Currently Under Warranty. Refer To The SRT Microfiche For Warranty Terms).
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