SUBJECT: Cold Start Stumble, RPM Flare (MTX), Performance With A/C On, Radiator Steams
NO: 18-28-96
GROUP: Vehicle Performance
DATE: Oct. 4,1996
MODELS: 1997 (PL) Neon
NOTE: THIS BULLETIN APPLIES TO 1997 MODELS BUILT PRIOR TO SEPTEMBER 23, 1996 MDH (09-23-XX).
SYMPTOM/CONDITION:

1. Engine stumble within 10 seconds of a cold start. If this condition persists after repair, it is recommended to change fuel brands.
2. RPM flares slightly when A/C or power steering loads are released, MTX only.
3. Vehicle lacks performance on low speed tip-in with A/C on, more noticeable on ATX vehicles. Does not improve vehicle launch performance.
4. Radiator "steams" during warm-up.
DIAGNOSIS:
Using the Mopar Diagnostic System (MDS) or the Diagnostic Scan Tool (DRB III) with the appropriate Diagnostic Procedures Manual, verify all engine/transmission systems are functioning as designed. If Diagnostic Trouble Codes (DTC's) are present, record them on the repair order and repair as necessary before proceeding further with this bulletin.

Test the Idle Air Control (IAC) by performing the IAC wiggle test. Select Engine System Test, IAC wiggle test, follow screen prompts. If the IAC wiggle test fails, repair as necessary before proceeding. If the IAC wiggle test passes and no DTC's are present, perform the Repair Procedure.
EQUIPMENT REQUIRED:

All Symptoms (Flash Programming)

1 CH6000 Scan Tool (DRB III) )
1 CH7035 General Purpose Interface Bus Cable (GPIB)
1 CH7000 J1962 Cable
1 4669020 Label - Authorized Software Update
1 4275086 Label -Authorized Modification

NOTE: THE MDS AND DRBIII ARE REQUIRED TO PERFORM THIS REPAIR AND THE SYSTEM MUST BE OPERATING WITH RELEASE 20 OR HIGHER AND TIL CD RELEASE 1117 OR HIGHER MUST BE INSTALLED.
REPAIR PROCEDURE:

This repair involves selectively erasing and reprogramming the Powertrain Control Module(PCM) with new software (calibration changes) for all conditions listed.

1. Connect the MDS (Mopar Diagnostic System) and DRB III (Scan Tool) to the vehicle and power them up.
2. Use the arrow keys and select #2 MDS DIAGNOSTICS on the DRB III MAIN MENU Screen.
3. Use the arrow keys and select DIAGNOSTIC MENU on the MDS, then press NEXT MENU.
4. Use the arrow keys and select VEHICLE CONTROLLER PROGRAMMING on the MDS, then press NEXT MENU.
5. Use the arrow keys and select PROGRAMMING OF ALL OTHER CONTROLLERS USING MDS & DRBIII on the MDS, then press NEXT MENU.
6. Follow the steps presented on the MDS and DRB III which will allow the DRB III to obtain the current part number of the PCM.
7. The MDS will display the part number of the PCM on the vehicle and the appropriate replacement part number, then press NEXT MENU to begin programming.
If the PCM on the vehicle has already been updated or programmed, a NO UPDATES AVAILABLE message will be displayed. Check the part number of the PCM on the vehicle and compare it to the part number displayed. If the PCM has already been updated, then another condition exists that will require further diagnosis and repair.
8. The MDS and DRB III will prompt for any operator action needed during the remainder of the programming process.

NOTE: THE FOLLOWING STEPS ARE REQUIRED BY LAW.

9 Type the necessary information on the "Authorized Software Update Label" P/N 4669020. Attach the label to the PCM and cover the label with the clear plastic cover.
10. Type the necessary information on the Authorized Modification Label and attach the label near the VECI Label.
POLICY: Reimbursable within the provisions of the warranty.