P050B - Cold Start Ignition Timing Performance

Fig 1: Throttle Position Sensor Wiring Diagram

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

For a complete wiring diagram, refer to appropriate Wiring Diagram.

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 temperature and engine coolant temperature 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 (K447) ETC POSITIVE CIRCUIT
EXCESSIVE RESISTANCE IN THE (K448) ETC NEGATIVE CIRCUIT
ETC MOTOR/THROTTLE BODY
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Refer to PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE .

Test Step 1 - ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)

Ignition on, engine not running.

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.

Start the engine.
Allow the engine to reach normal operating temperature.
With a scan tool, read 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 Test Step 2

Perform the Checking for an Intermittent DTC diagnostic procedure. Refer to CHECKING FOR AN INTERMITTENT DTC .

Test Step 2 - THROTTLE PLATE INSPECTION

Turn the ignition off.
Remove the Air Cleaner Assembly from the Throttle Body.
Check for any signs of a foreign material (ice, dirt, or excessive carbon build up) on the Throttle Plate or in the bore causing the Throttle Plate to stick.

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. Refer to REMOVAL AND INSTALLATION .
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Go to Test Step 3

Test Step 3 - DIRTY AIR FILTER

Remove and inspect the Air Filter.

Is the Air Filter dirty?

Yes

Replace the Air Filter. Refer to REMOVAL AND INSTALLATION .
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Go to Test Step 4

Test Step 4 - CONTAMINATED FUEL

Inspect the Fuel for contamination. (Dirt, water, or other foreign material)

Is the fuel contaminated?

Yes

Drain the Fuel from the fuel tank into an approved gas holding tank and add clean fuel.

Go to Test Step 5

Test Step 5 - EXCESSIVE RESISTANCE IN THE (K447) ETC POSITIVE CIRCUIT

Turn the ignition off.
Using a Voltmeter perform a voltage drop test. Back probe the (K447) ETC Positive circuit at the Throttle Body harness connector and PCM C2 harness connector. Make sure the Voltmeter leads are connected so a positive polarity is displayed on the Voltmeter.

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.

Start the engine and allow it to reach normal operating temperature.
Monitor the Voltmeter.

Is the voltage below 0.5 volt?

Yes

Go to Test Step 6

Repair the excessive resistance in the (K447) ETC Positive circuit.
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Test Step 6 - EXCESSIVE RESISTANCE IN THE (K448) ETC NEGATIVE CIRCUIT

Turn the ignition off.
Move the Voltmeter leads to back probe the (K448) ETC Negative circuit at the Throttle Body harness connector and the PCM C2 harness connector. Make sure the Voltmeter leads are connected so a positive polarity is displayed on the Voltmeter.
Start the engine and allow it to reach normal operating temperature.
Monitor the Voltmeter.

Is the voltage below 0.5 volt?

Yes

Go to Test Step 7

Repair the excessive resistance in the (K448) ETC Negative circuit.
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Test Step 7 - ETC MOTOR

Fig 2: Testing ETC Motor Resistance

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

Turn the ignition off.
Connect the Throttle Body harness connector.
Measure the resistance of the ETC Motor by probing the PCM C2 harness connector for the (K447) ETC Positive circuit and the (K448) ETC Negative circuit.

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

Yes

Go to Test Step 8

Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors. Replace the Throttle Body Assembly if no problems were found in the connectors. Disconnect the Battery when replacing the Throttle Body Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function. Refer to REMOVAL AND INSTALLATION .
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Test Step 8 - POWERTRAIN CONTROL MODULE (PCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Throttle Body Assembly and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Throttle Body and Powertrain Control Module connectors.
Perform any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

Repair as necessary.
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .

Replace and program the Powertrain Control Module (PCM). Refer to REMOVAL AND INSTALLATION .
Perform the Powertrain Verification Test. Refer to PCM VERIFICATION TEST (2009 - 2011) or PCM VERIFICATION TEST (2012 & UP) .