DTC 4-1-4

4-1-4 CHARGE PRESSURE CONTROL

Preconditions for DTC
^ The ECM calculates charge pressure by using the signal from the Mass Air Flow (MAF) sensor. When the ECM considers that the MAF sensor is correct and the load signal exceeds a preset level, DTC 4-1-4 is set.

Substitute value
^ The system only permits initial charge pressure.

Fault sources
^ Defective MAF sensor.
^ Contact resistance in connectors.
^ Break in the lead to the charge pressure reduction from AW 50-42.
^ Clogged hoses between Turbocharger (TC) and TC control valve, and TC control valve and pressure servo respectively.
^ Defective TC control valve.
^ Defective pressure servo to the wastegate valve.
^ Seized wastegate valve.

Fault symptoms
^ When charge pressure reaches the max. limit fuel injection is stopped. As a result, the engine becomes very jerky.
^ Poorer performance from initial charge pressure limit.

TESTING PROCEDURE





Checking the MAF Sensor
^ Switch Ignition ON.
^ MAF sensor connected.
^ Connect a voltmeter between the MAF sensor's connectors 2 and 4.

The voltmeter should show 0.1 - 0.2 Volt.

If the reading is OK:
- Check the lead for charge pressure reduction.
If the reading is incorrect:
- Check the connectors.





Checking the Connectors
^ Switch Ignition OFF.
^ Rectify the MAF sensor's and the ECM's connectors with regard to contact resistance and oxidation.
^ MAF sensor connected.
^ ECM connected.
^ Switch Ignition ON.





^ Connect a voltmeter between the MAF sensor's connectors 2 and 4.

The voltmeter should show 0.1 - 0.2 Volts.

If the reading is OK:
- The source of the DTC is poor contact in the MAF sensor's and/or the ECM's connector.
If the reading is incorrect:
- Test with a new MAF sensor.





Checking the Lead for Charge Pressure Reduction
^ Switch Ignition OFF.
^ Connect the break-out box and check the ground points.
^ Disconnect the ECM.
^ Switch Ignition ON.





^ Connect a voltmeter between connector #42 (ECM B42) on the break-out box and ground.

The voltmeter should show battery voltage.

If the reading is OK:
- Check the connectors.
If the reading is incorrect:
- Check the lead between ECM B42 and TCM B1 for signs of an intermittent break.





Checking the Connectors
^ Switch Ignition OFF.
^ Rectify the TC control valve's and the ECM's connectors with regard to contact resistance and oxidation.
^ TC control valve connected.
^ ECM connected.
^ Switch Ignition on.





^ Check with DTM 3 that the TC control valve functions (ticks).

If the TC control valve functions (ticks):
- Check the hoses.
If the TC control valve does not function (no ticking):
- Test with a new TC control valve.





Checking the Hoses
^ Ignition off.
^ Check that the hose between the turbocharger (TC) and TC control valve, and the hose between the TC control valve and pressure servo for the wastegate valve, are not blocked or pinched.
^ Check also that the TC control valve is not blocked between the red and yellow connectors (when the valve is not activated, it should be open between the red and yellow connectors).

If the hoses and TC control valve are OK:
- Check the pressure servo.
If the hoses and/or TC control valve are blocked:
- Clean; if necessary, replace.





Checking the Pressure Servo
^ Switch Ignition OFF.
^ Release the hose from the pressure servo.
^ Connect manometer P/N 9995230 and pressure tester P/N 9985496 to the pressure servo.
^ Pump up a pressure of approx. 75 kPa (46.6 psi).
^ The pressure servo should open fully at this pressure.

NOTE: This pressure is not an adjustment value.

^ Check also that the wastegate valve is not seizing.

If the pressure servo is OK:
- Check the pressure servo setting.
- If needed: Replace the wastegate valve pressure servo.
If the pressure servo is not OK:
- Test with a new pressure servo.
- If needed: Replace the wastegate valve pressure servo.