P050D-COLD START ROUGH IDLEFor a complete wiring diagram Refer to Section 8WTheory of OperationThe objective of the Dynamic Crankshaft Fuel Control is to reduce the fuel as much as possible during a cold start. The 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.
Diagnostic Test1.CHECKING FOR CYLINDER MISFIRE CONDITION PRESENTCheck for any TSBs that apply to a Misfire condition. Review the vehicle repair history for any misfire condition repairs that have been performed.Reviewing the vehicle repair history may aid in the repair of the misfire condition.Ignition on, engine not running.With a scan tool, select View DTCs.Is P0300 or any other Misfire DTCs set along with the P050D.Is there a misfire present at this time?YesRefer to the appropriate Cylinder Misfire Diagnostic procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 22.ACTIVE DTCDiagnose all other trouble codes before continuing.Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.Start the engine.Allow the engine to reach normal operating temperature.With a scan tool, select View DTCs.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?YesGo To 3NoRefer to the INTERMITTENT CONDITION Diagnostic Procedure.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)3.CHECKING FUEL PRESSURE The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must
be released. Failure to follow these instructions can result in personal injury or death. Install a fuel pressure gauge to the fuel rail.Ignition on, engine not running.With a scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.The DTC needs to be cleared before actuating the System Test, if the DTC is not cleared, the System Test may not be allowed to actuate.Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).Turn the ignition off.Choose a conclusion that best matches your fuel pressure reading.Within SpecificationGo To 4Above SpecificationReplace the fuel filter/pressure regulator.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)Below SpecificationGo To 13 Stop All Actuations.4.O2 SENSOR OPERATIONStart the engine.Allow the engine to reach normal operating temperature.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.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.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.With a 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?YesGo To 5NoGo To 95.1/1 O2 SENSOR HEATER OPERATIONTurn the ignition off.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.Ignition on, engine not running.With a scan tool, actuate the 1/1 O2 Heater Test.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.With the scan tool, monitor 1/1 O2 Sensor voltage for at least 2 minutes.Does the voltage stay above 4.5 volts?YesReplace the 1/1 O2 Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 66.MAP SENSOR OPERATIONTurn the ignition off.Connect a Vacuum Gauge to a Manifold Vacuum source.Start the engine.Allow the engine to idle.If engine will not idle, maintain a constant RPM above idle.With the scan tool, read the MAP Sensor vacuum value.Is the scan tool reading within 1" of the Vacuum Gauge reading?YesGo To 7NoReplace the MAP Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)7.ECT SENSOR OPERATIONFor this test to be valid, the thermostat must be operating correctly.This test works best if performed on a cold engine (cold soak)Ignition on, engine not running.With a 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.If engine coolant temperature is above 82° C (180° F), allow the engine to cool until 65° C (150° F) is reached.Start the Engine.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)?YesGo To 8NoReplace the Engine Coolant Temperature Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)8.ENGINE MECHANICAL PROBLEMTurn the ignition off.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 neutralENGINE VALVE TIMING - must be within specificationsENGINE COMPRESSION - must be within specificationsENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.ENGINE PCV SYSTEM - must flow freelyTORQUE CONVERTER STALL SPEED - must be within specificationsPOWER BRAKE BOOSTER - no internal vacuum leaksFUEL - must be free of contaminationFUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injectorAre there any engine mechanical problems?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 129.1/1 O2 SENSORIgnition on, engine not running.Disconnect the 1/1 O2 Sensor harness connector.With a scan tool, monitor the 1/1 O2 Sensor voltage.O2 Sensor voltage should read 5.0 volts on the scan tool with the connector disconnected.Connect a jumper wire between the (K41) Signal circuit and the (K902) O2 Upstream Return circuit in the O2 Sensor harness connector.The voltage should drop from 5.0 volts to 2.5 volts with the jumper wire in place.Did the O2 Sensor voltage change from 5.0 volts to 2.5 volts with the jumper wire installed?YesReplace the O2 Sensor.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 10Remove the jumper wire before continuing.10.(K41) O2 SENSOR 1/1 SIGNAL CIRCUITWith a scan tool, monitor the 1/1 O2 Sensor voltage reading with the jumper wire removed.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.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 above 4.8 volts?YesGo To 11NoCheck 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 per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)11. (K902) O2 UPSTREAM RETURN CIRCUITDisconnect the 1/1 O2 Sensor harness connector.Measure the voltage on the (K902) O2 Upstream Return circuit in the O2 Sensor harness connector.Is the voltage at 2.5 volts?YesGo To 12NoCheck 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 per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)12.PCMBefore continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.Were there any problems found?YesRepair as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoReplace and program the Powertrain Control Module per Service Information.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)13.RESTRICTED FUEL SUPPLY LINE The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must
be released. Failure to follow these instructions can result in personal injury or death. Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.Install special 5/16 fuel line adapter tool #6539 between disconnected fuel line and the fuel pump module.Attach a fuel pressure test gauge to the T fitting on tool #6539.Ignition on, engine not running.With a scan tool, actuate the ASD Fuel System test and observe the fuel pressure gauge.The DTC needs to be cleared before actuating the System Test, if the DTC is not cleared, the System Test may not be allowed to actuate.Fuel pressure specification is 407 kPa +/- 34 kPa (59 psi +/- 5 psi).Is the fuel pressure within specification?YesRepair or replace fuel supply line as necessary.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 14Stop All Actuations. 14.FUEL PUMP INLET STRAINERThe fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must
be released.Turn the ignition off.Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.Is the Fuel Inlet Strainer plugged?YesReplace the Fuel Pump Inlet Strainer.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)NoGo To 1515.FUEL PUMP MODULEIf there are no possible causes remaining, view repair.RepairReplace the Fuel Pump Module.Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)