P2174
P2174-LOW AIRFLOW/RESTRICTION DETECTED (INSTANTANEOUS ACCUMULATION)
For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.
- When Monitored:
Engine speed is above 550 RPM has been running for more than one second and the total effective throttle area is below a certain threshold (mapped against engine speed).
- Set Condition:
The mass air flow value (g/s) of sensor 1 is lower than and does not correlate with the estimated mass air flow value for sensor 1 and the mass air flow value (g/s) of sensor 2 does correlate with the estimated mass air flow value of sensor 2 and the manifold pressure sensor value (kPa) does correlate with the estimated manifold pressure value.
OR
The mass air flow value (g/s) of sensor 1 does correlate with the estimated mass air flow value for sensor 1 and the mass air flow value (g/s) of sensor 2 is lower than and does not correlate with the estimated mass air flow value of sensor 2 and the manifold pressure sensor value (kPa) does correlate with the estimated manifold pressure value. One trip fault. Three good trips to turn of the mil. ETC light will flash.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure
1. ACTIVE DTC
NOTE: The most likely cause of this DTC is a plugged intake air system or Dirty Throttle Body. Check for TSBs before continuing.
NOTE: Diagnose any 5-Volt Supply, TP Sensor, Fuel System Lean or Rich, IAT Sensor, MAF Sensor, or MAP Sensor DTCs before continuing.
NOTE: The throttle plate should be free from binding and carbon build up.
NOTE: Question the customer about weather conditions, as ICE build up on the blade can cause this fault when ambient is around -10° C (14 ° F) to 4° C (39° F) range.
1. Ignition on, engine not running.
2. With a scan tool, select View DTCs.
Is the DTC Active at this time?
Yes
- Go To 2
No
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Checking for an Intermittent DTC
2. RESTRICTED AIR INLET SYSTEM
1. Turn the ignition off.
2. Remove the Air Cleaner Assembly.
3. Remove the Air Filter.
4. Inspect the Throttle Body opening for signs of any foreign materials.
5. Check the intake tube/air cleaner for obstructions - include snow packing questions to customer.
Were any restrictions found?
Yes
- Repair the restriction as necessary.
- Perform the PCM Verification Test. PCM Verification Test
No
- Go To 3
3. MAP SENSOR OPERATION
1. Start the engine.
2. With a scan tool, monitor the MAP Sensor voltage.
3. Snap the Accelerator pedal.
Does the MAP Sensor voltage vary from below 2.0 volts at idle to above 3.5 volts at Wide Open Throttle?
Yes
- Go To 4
No
- Refer to the Trouble code diagnostic procedures for the MAP Sensor.
4. TP SENSOR OPERATION
1. Ignition on, engine not running.
2. With a scan tool, perform the Throttle Follower Test.
3. TP 1 Sensor No.1 should start at approximately 0.7 of a volt and increase to 4.3 volts.
4. TP 1 Sensor No.2 should start at approximately 4.3 volts and decrease to 0.7 of a volt.
5. TP 2 Sensor No.1 should start at approximately 0.7 of a volt and increase to 4.3 volts.
6. TP 2 Sensor No.2 should start at approximately 4.3 volts and decrease to 0.7 of a volt.
Is the voltage transition smooth between the appropriate values?
Yes
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Checking for an Intermittent DTC
No
- Go To 5
5. PCV SYSTEM
1. Inspect the PCV system for the following problems:
2. Restrictions - sticking valve, collapsed hoses or tubes, obstructed passages or ports, etc.
3. Leaks - cracked or damaged hoses or tubes, poor hose or tube connections, PCV valve stuck open, etc.
Were any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. PCM Verification Test
No
- Go To 6
6. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the MAP Sensor, Throttle Body, and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the MAP Sensor, Throttle Body, and Powertrain Control Module connectors.
4. Search for any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the PCM Verification Test. PCM Verification Test
No
- Replace and program the Powertrain Control Module.
- Perform the PCM Verification Test. PCM Verification Test