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Home >> Pontiac >> 2001 >> Firebird Formula, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 5.7L >> Diagnostic Tests >> DTC P0101: Mass Airflow Sensor Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. If powertrain diagnostic system check was performed, go to next step. If powertrain diagnostic system check was not performed, go to POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under DIAGNOSTIC SYSTEM TESTS. After performing powertrain diagnostic system check, go to next step.
  2. Check for any additional DTCs. If any other DTCs are set, diagnose those DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no other DTCs are set, go to next step.
  3. Turn ignition on. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for at least 30 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME and/or FAILURE RECORDS as possible. Select DTC function, then enter this DTC. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS .
  4. Start engine and allow to idle. Using scan tool, monitor MAP sensor voltage. If MAP sensor voltage in 0.8-4.0 volts, go to next step. If MAP sensor voltage in not 0.8-4.0 volts, go to DTC P0106: MANIFOLD ABSOLUTE PRESSURE SENSOR OUT OF RANGE .
  5. Turn engine off. Check for blockage in MAF sensor inlet screen, intake manifold leak, vacuum leak at throttle body, leak at EGR valve flange and pipes, or faulty PCV valve. Repair or replace as necessary. After repairs, go to step  23. If no problem is found, go to next step.
  6. Locate and remove vacuum source from MAP sensor. See Figure. Connect a hand-held vacuum pump to MAP sensor. Turn ignition on. Note scan tool MAP sensor kPa reading with no vacuum applied. While monitoring scan tool MAP sensor kPa reading, apply one in. Hg at a time until 20 in. Hg is reached. If MAP kPa reading drops 3-4 kPa for each one in. Hg of vacuum applied and drops smoothly to 20 in. Hg of applied vacuum, go to next step. If MAP kPa reading does not drop 3-4 kPa for each one in. Hg of vacuum applied or does not drop smoothly to 20 in. Hg of applied vacuum, go to DTC P0106: MANIFOLD ABSOLUTE PRESSURE SENSOR OUT OF RANGE .
  7. Apply 20 in. Hg of vacuum to MAP sensor. If MAP sensor kPa reading on scan tool is 34 kPa or less, go to next step. If MAP sensor kPa reading is more than 34 kPa, go to DTC P0106: MANIFOLD ABSOLUTE PRESSURE SENSOR OUT OF RANGE .
  8. Release vacuum from hand-held vacuum pump. If MAP sensor reading returns to original value noted in step  6, go to next step. If reading does not return to original value, go to DTC P0106: MANIFOLD ABSOLUTE PRESSURE SENSOR OUT OF RANGE .
  9. Using scan tool, monitor Throttle Position (TP) sensor angle while opening and closing throttle plate from closed to wide open and back to closed. If TP sensor angle changes smoothly from zero to 100 percent, go to next step. If TP sensor angle does not change smoothly from zero to 100 percent, go to DTC P0121: THROTTLE POSITION SENSOR CIRCUIT INSUFFICIENT ACTIVITY .
  10. Turn ignition off. Locate and disconnect MAF sensor connector. See Figure. Turn ignition on. Using DVOM, measure voltage between ground and MAF sensor connector terminal "A" (Yellow wire). If voltage is about 5 volts, go to next step. If voltage is not as specified, go to step  12.
  11. Connect a test light between MAF sensor connector terminals "A" (Yellow wire) and "B" (Black/White wire). If test light illuminates, go to step  19. If test light does not illuminate, go to step  14.
  12. If voltage is less than 4.5 volts, go to step  15. If voltage is more than 4.5 volts, go to next step.
  13. Turn ignition off. Locate and disconnect PCM Red connector C2. See Figure. Turn ignition on. Using DVOM, measure voltage between ground and PCM connector C2 terminal No. 31 (Yellow wire). See Figure. If voltage is about zero volts, go to step  22. If voltage is other than specified, go to step  18.
  14. Using a test light connected to ground, probe MAF sensor connector terminal "C" (Pink wire). If test light illuminates, go to step  16. If test light does not illuminate, go to step  17.
  15. Turn ignition off. Using DVOM, check for an open, short to ground or short to MAF sensor ground in Yellow wire between MAF sensor connector terminal "A" and PCM connector C2 terminal No. 31. Repair as necessary. After repairs, go to step  23. If circuit is okay, go to step  20.
  16. Repair open or high resistance in Black/White wire between MAF sensor connector terminal "B" and ground connection located on rear of driver's cylinder head. After repairs, go to step  23.
  17. Repair open or short to ground in Pink wire between MAF sensor connector terminal "C" and ENG SEN fuse (20-amp) located in bottom underhood fuse block. See Figure and Figure . Replace fuse if necessary. After repairs, go to step  23.
  18. Repair short to voltage in Yellow wire between MAF sensor PCM. After repairs, go to step  23.
  19. Check for poor connections at MAF sensor connector. Repair as necessary. After repairs, go to step  23. If connections are okay, go to step  21.
  20. Check for poor connections at PCM connector C2. Repair as necessary. After repairs, go to step  23. If connections are okay, go to step  22.
  21. Replace MAF sensor. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing sensor, go to step  23.
  22. Replace PCM. See REMOVAL, OVERHAUL & INSTALLATION - CARS article. After replacing PCM, go to next step.
  23. Using scan tool, clear DTCs. Turn ignition off for at least 30 seconds. Start engine and allow it to reach normal operating temperature. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, go to step  2.
  24. Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no undiagnosed DTCs are displayed, system is okay.
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