P050D
P050D-COLD START ROUGH IDLE
Theory of Operation
The objective of the Dynamic Crankshaft Fuel Control (DCFC) is to reduce the fuel as much as possible during a cold start. The Dynamic Crankshaft Fuel Control (DCFC) begins subtracting fuel from a high limit upon a cold start and keeps removing fuel in an attempt to get to a calibrated lean limit. DCFC stops removing fuel when rough idle is detected or the lean limit is reached.
- When Monitored:
Cold start condition. Ambient Air temperature between -7° C and 50° C (19.4° F and 122° F). Engine Coolant temperature between -7° C and 50° C (19.4° F and 122° F). The difference between the Ambient Air temp and ECT temp at Start is equal to or less than 10° C (50° F). Engine running at idle only.
- Set Condition:
If a rough idle is detected and the Dynamic Crankshaft Fuel Control remains or returns to the high limit window for a calibrated time. Two trip fault.
1. CHECKING FOR CYLINDER MISFIRE CONDITION PRESENT
NOTE: Check for any TSBs that apply to a Misfire condition. Review the vehicle repair history for any misfire condition repairs that have been performed.
NOTE: Reviewing the vehicle repair history may aid in the repair of the misfire condition.
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.
3. With the scan tool, select View DTCs.
Is P0300 or any other Misfire DTCs set along with the P050D?
Yes
- Perform the appropriate Cylinder Misfire diagnostic procedure.
No
- Go To 2
2. ACTIVE DTC
NOTE: Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
NOTE: Diagnose and repair any other DTCs before continuing with this test.
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
3. With the scan tool, select View DTCs.
NOTE: It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.
Is the DTC Active or Pending at this time?
Yes
- Go To 3
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.
3. CHECKING THE FUEL DELIVERY SYSTEM
1. Checking the Fuel Delivery System Perform the diagnostic procedure for Checking the Fuel Delivery System.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. O2 SENSOR OPERATION
1. Start the engine.
2. Allow the engine to reach normal operating temperature.
NOTE: If one of the O2 Sensor's Signal or Return circuit is shorted to ground the scan tool will display all O2 Sensor voltage readings low. The O2 Sensor that is shorted to ground will display a voltage reading near or at 0 Volts.
NOTE: If one of the O2 Sensor Signal or Return circuits are shorted to voltage, the scan tool will display all O2 Sensor voltage readings high.
NOTE: After the repairs have been made, verify proper O2 Sensor operation. If all the O2 Sensor voltage readings have not returned to normal, follow the diagnostic procedure for the remaining O2 Sensors.
3. With the scan tool, monitor all of the O2 Sensor voltage readings.
Is the voltage switching between 2.5 and 3.4 Volts for all the O2 Sensors?
Yes
- Go To 5
No
- Go To 9
5. 1/1 O2 SENSOR HEATER OPERATION
1. Turn the ignition off.
NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 Volts.
2. Ignition on, engine not running.
3. With the scan tool, actuate the 1/1 O2 Heater Test.
NOTE: The DTC needs to be cleared before actuating the Heater Test, if the DTC is not cleared, the Heater Test may not be allowed to actuate.
4. With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes.
Does the voltage stay above 4.5 Volts?
Yes
- Verify that there is good pin to terminal contact in the 1/1 O2 Sensor and the Powertrain Control Module connectors. Replace the 1/1 O2 Sensor if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 6
6. MAP SENSOR OPERATION
1. Turn the ignition off.
2. Connect a Vacuum Gauge to a Manifold Vacuum source.
3. Start the engine.
4. Allow the engine to idle.
NOTE: If engine will not idle, maintain a constant RPM above idle.
5. With the scan tool, read the MAP Sensor vacuum value.
Is the scan tool reading within 1" of Hg on the Vacuum Gauge reading?
Yes
- Go To 7
No
- Verify that there is good pin to terminal contact in the MAP Sensor and the Powertrain Control Module connectors. Replace the MAP Sensor if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
7. ECT SENSOR OPERATION
NOTE: For this test to be valid, the thermostat must be operating correctly.
NOTE: This test works best if performed on a cold engine (cold soak)
1. Ignition on, engine not running.
2. With the scan tool, read the Engine Coolant Temperature (ECT) Sensor value. If the engine was allowed to sit overnight (cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
NOTE: If engine coolant temperature is above 82° C (180° F), allow the engine to cool until 65° C (150° F) is reached.
3. Start the Engine.
4. During engine warm-up, monitor the ECT Sensor value. The temperature value change should be a smooth transition from start up to normal operating temperature 82° C (180° F). The value should reach at least 82° C (180° F).
Did the ECT value increase smoothly and did it reach at least 82° C (180° F)?
Yes
- Go To 8
No
- Verify that there is good pin to terminal contact in the ETC Sensor and the Powertrain Control Module connectors. Replace the Engine Coolant Temperature Sensor if no problems were found in the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
8. ENGINE MECHANICAL PROBLEM
1. Turn the ignition off.
2. Check for any of the following conditions/mechanical problems:
- AIR INDUCTION SYSTEM - must be free from leaks.
- ENGINE VACUUM - must be at least 13 inches in neutral
- ENGINE VALVE TIMING - must be within specifications
- ENGINE COMPRESSION - must be within specifications
- ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
- ENGINE PCV SYSTEM - must flow freely
- TORQUE CONVERTER STALL SPEED - must be within specifications
- POWER BRAKE BOOSTER - no internal vacuum leaks
- FUEL - must be free of contamination
- FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector
Are there any engine mechanical problems?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 12
9. 1/1 O2 SENSOR
1. Turn the ignition off.
2. Disconnect the 1/1 O2 Sensor harness connector.
3. Ignition on, engine not running.
4. With the scan tool, monitor the 1/1 O2 Sensor voltage.
5. O2 Sensor voltage should read between 4.1 and 5.0 Volts on the scan tool with the connector disconnected.
6. Connect a jumper wire between the (K41) O2 1/1 Signal circuit and the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
NOTE: The voltage should drop from between 4.1 and 5.0 Volts to 2.5 Volts with the jumper wire in place.
Did the O2 Sensor voltage change from between 4.1 and 5.0 Volts to 2.5 Volts with the jumper wire installed?
Yes
- Verify that there is good pin to terminal contact in the related Sensors and the Powertrain Control Module connectors. Replace the 1/1 O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 10 NOTE: Remove the jumper wire before continuing.
10. (K41) O2 SENSOR 1/1 SIGNAL CIRCUIT
1. With the scan tool, monitor the 1/1 O2 Sensor voltage reading with the jumper wire removed.
NOTE: The scan tool will display all O2 Sensor voltage readings approximately 5.0 Volts when only one O2 Sensor's Signal circuit is shorted to voltage.
NOTE: The scan tool will display one O2 Sensor voltage close to zero and the others will read lower than normal when one O2 Sensor Signal circuit contains excessive resistance.
Is the voltage between 4.1 and 5.0 Volts?
Yes
- Go To 11
No
- Check the (K41) O2 Sensor 1/1 Signal circuit for a short to ground, open or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
11. (K902) O2 RETURN UPSTREAM CIRCUIT
1. Measure the voltage on the (K902) O2 Return Upstream circuit in the O2 Sensor harness connector.
Is the voltage at 2.5 Volts?
Yes
- Go To 12
No
- Check the O2 Return circuit for a short to ground, open or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
12. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the related Sensors 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 related Sensors and the Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.