Engine - Ping Under Slight Acceleration
Bulletin No. 007/96Issued 04/04/96
Revised
Category F
Applicable Model/s 1994 B-2300 (M/T Only)
Subject
ENGINE PING UNDER SLIGHT ACCELERATION (Highway Speeds In High Ambient Temperatures)
APPLICABLE MODEL
All 1994 B-2300 vehicles with a manual transmission and a calibration code of 4-49U-R05, 4-49U-R10 or 4-49T-R10*.
IMPORTANT: This repair is not authorized for vehicles with 4.10 axle ratio for 4WD and those with other than the above calibration codes. Performing this repair on unauthorized vehicles may be in violation of state and federal law.
DESCRIPTION
A slight ping noise which occurs under light acceleration and ambient temperatures above 70 degrees (F) [21 degrees (C)] may be caused by an aggressive spark timing. An updated PCM (Powertrain Control Module) is available to retard timing during these conditions and reduce pinging.
Customers complaining of this noise should be asked what octane rating they are using to fuel their vehicles. If the octane is less than 87, request that they first try fueling the vehicle consistently with the recommended 87 octane fuel. Note this occurrence on an R.O.
Customers using at least 87 octane fuel should have the vehicle inspected and repaired according to this bulletin.
REPAIR PROCEDURE
1. Verify the concern in temperatures above 70 degrees (F) [21 degrees (C)].
2. Confirm that the calibration code is 4-49U-R05, 4-49U-R10 or 4-9T-R10*.
NOTE:
Calibration label is attached to the driver's side "B" pillar.
^ If the vehicle has the symptoms and the calibration code is 4-49U-R05 or 4-49U-R10 or 4A9T-R10* proceed to step 3.
^ If the vehicle has the symptoms but does not have any of the calibration codes, refer to the workshop manual for troubleshooting and repair information.
*NOTE:
Check that the Engineering Part Number F4PF-12A650-MA is on the PCM. This number is located just below the bar code label on the PCM connector.Vehicles with this PCM have an updated calibration code (4-49T-R10) as a result of repairs described in S/B Cat. F # 007/95. Proceed to step 3 with these vehicles as well.
3. Confirm that the cooling system is functioning properly.
4. Perform normal diagnostic tests. Refer to section F of the workshop manual.
^ If any DTCs are present, repair vehicle as necessary.
5. Verify the concern.
^ If concern is still present, install the updated PCM.
^ If the concern no longer exists, return the vehicle to the customer.
NOTE:
If the vehicle has calibration number 4-49U-R05 and the PCM DOES NOT HAVE Engineering Part Number F4PF-12A650-MA replace the idle air control motor (IAC) with a new level part.
6. List the date, dealer number and Service Bulletin number of the "PCM Replacement Label" and install the label on the radiator support.
NOTE: This label informs technicians of the PCM changes if future repairs are necessary.
7. Perform all diagnostic procedures to confirm that there are no DTCs present.
8. Confirm that the ping is reduced.
PARTS INFORMATION
WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Covered Under Normal Warranty. Refer To The SRT Microfiche For Warranty Term Application.)
Warranty Type: A
Symptom Code: 11
Damage Code: 9W
Part Number Main Cause: ZZMJ 18 881
Quantity: 1
Operation Number/Labor Hours: YY0232RX / 0.8 Hrs. (R&R PCM)
YY0233RX / 1.1 Hrs. (R&R PCM & IAC)
NOTE: Both labor times listed above include allowances for diagnostics.