P050B-COLD START IGNITION TIMING PERFORMANCE (ETC)





For a complete wiring diagram Refer to Section 8W.

Theory of Operation


Spark adjustment during a cold start is intended to provide quick response to idle speed variations. The spark adjust diagnostics monitors spark advance on a cold start over a period of time, then compares the average spark advance to a threshold.

  • 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:

    Engine RPM is 50 RPM or more (depending on vehicle specifications), below idle speed for at least 3 seconds and the average spark advance is above the threshold, too much spark advance, for a specified time limit. Two trip fault. Three good trips to turn off the MIL.


Possible Causes
  
RESTRICTED INTAKE AIR SYSTEM
  
LOW BATTERY VOLTAGE
  
FUEL CONTAMINATION
  
EXCESSIVE RESISTANCE IN THE (K124) ETC POSITIVE CIRCUIT
  
EXCESSIVE RESISTANCE IN THE (K126) ETC NEGATIVE CIRCUIT
  
ETC MOTOR/THROTTLE BODY
  
PCM
  

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING).



Diagnostic Test

1.ACTIVE DTC


NOTE: Low battery voltage can also cause excessive current draw, in very hot and very cold ambient temperatures. Make sure the battery can pass a load test before continuing.





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 2


No

2.THROTTLE PLATE INSPECTION





Were any signs of foreign material or scoring of the throttle plate or bore found?

Yes
  • Remove the debris if possible or replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function.
  • Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)


No
  • Go To 3

3.DIRTY AIR FILTER



Is the Air Filter dirty?

Yes


No
  • Go To 4

4.CONTAMINATED FUEL



Is the fuel contaminated?

Yes


No
  • Go To 5

5.EXCESSIVE RESISTANCE IN THE (K124) ETC POSITIVE CIRCUIT



CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 along with the #8815-1 to perform the diagnosis.



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 can result in personal injury or death.





Is the voltage below 0.5 of a volt?

Yes
  • Go To 6


No

6.EXCESSIVE RESISTANCE IN THE (K126) ETC NEGATIVE CIRCUIT



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 can result in personal injury or death.





Is the voltage below 0.5 of a volt?

Yes
  • Go To 7


No

7.ETC MOTOR




NOTE: Take the following measurement using special tool #8815 to avoid possible damage to the Throttle Body harness connector.






Is the resistance between 2.5 and 25 ohms at closed throttle?

Yes
  • Go To 8


No
  • Replace the Throttle Body Assembly. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function.
  • Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)

8.PCM

NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.




Were there any problems found?

Yes


No