Mass Air Flow Sensor - MIL ON/Driveability Concerns
Bulletin No.: 002/97Issued: 03/10/97
Revised
Category
F
Applicable Model/s
1994-96
626/MX-6 (2.0L, A/T)
Subject:
DIAGNOSTIC PROCEDURE FOR MASS AIR FLOW SENSOR TROUBLES (DTC P0171/181)
AFFECTED MODELS/VINS
1994-95 626/MX-6 vehicles equipped with EEC-IV calibration (FS ATX)
1996 626/MX-6 vehicles equipped with EEC-V calibration (FS ATX) up to and including VIN 1YVGE**C*T5525968
DESCRIPTION
Some vehicles with over 20,000 miles may experience any or all of the symptoms listed below. This may be caused by contamination build-up on the heated elements of the mass airflow sensor (MAFS). MAFS with date codes after 5K05 (1995, October, 5th) are less susceptible to contamination. Customers complaining of these symptoms should have their vehicles inspected and, if necessary, repaired according to this bulletin.
SYMPTOMS
^ MIL illumination
^ Rough Idle
^ Hesitation
^ Lack of power
^ DTC 181 (OBD I vehicles)
NOTE:
DTC 181 may be alone or accompanied by the following DTCs: 157, 159, 172 and 173.
^ DTC P0171 (OBD II vehicles)
NOTE:
DTC P0171 may be alone or accompanied by the following DTCs: P0102, P1131 and P1132.
REPAIR PROCEDURE
1. Verify the customer complaint.
2. Retrieve and record any DTCs and Freeze Frame data stored in the PCM.
3. Attach a ventilation hose to the tail pipe and allow the engine to reach normal operating temperature.
4. Thoroughly check for vacuum and intake leaks or obstructions.
^ If no leaks or obstructions are found, proceed to step 5.
^ If a leak or obstruction is found, repair this condition and proceed to step 10. Refer to the workshop manual.
5. Check fuel system regulated and hold pressure per workshop manual.
^ If fuel pressure is found to be within specification, proceed to step 6.
^ If fuel pressure is found to be outside of specification, repair this condition and proceed to step 10. Refer to the workshop manual.
6. Check fuel injectors for proper operation, per workshop manual.
^ If the fuel injectors are found to be operating properly, proceed to step 7.
^ If the fuel injectors are found to be operating improperly, repair this condition and proceed to step 10. Refer to the workshop manual.
7. Monitor MAFS voltage in one of the following manners. Refer to the workshop manual.
^ OBD I vehicles (1994-95) - Install a 60 pin EEC-IV breakout box (SST # 49 UN01 058). Monitor voltage between pins 9 and 50.
^ OBO II vehicles (1996) - Install a 104 pin EEC-V breakout box (SST # 49 UN01 130) or use the NGS tester (SST # 49 T088 0A0) to monitor the MAFV PID signal.
NOTE:
If using the 104 pin breakout box, monitor the voltage between pins 88 and ground.
8. Place the vehicle in Park, set parking brake.
^ Turn off all electrical loads (i.e. heater fan, A/C, rear window defroster, headlights).
9. Increase engine speed to 5500 rpm (long enough to stabilize MAFS voltage) and record voltage.
^ If voltage is 2.30 volts and above the MAFS is good. Refer to the workshop manual for troubleshooting information.
^ If the voltage is below 2.30 volts, replace the MAFS. Refer to the instructions in the workshop manual.
10. Clear all DTCs and verity the repair.
PARTS INFORMATION
WARRANTY INFORMATION
(Applies To Verified Customer Complaints On Vehicles Covered Under Normal Warranty. Refer To The SRT Microfiche For Warranty Term Information.)
Warranty Type: A
Symptom Code: 62
Damage Code: 93
Part Number Main Cause: Refer to Parts Information
Quantity: 1
Operation Number/Labor Hrs.: F0008XDX / 1.8 Hrs. (Max. Diagnostic Time)
F0801XRX / 0.4 Hrs. (MAFS R&R)
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