Volkswagen Engine Misfire Diagnosis -

Volkswagen Engine Misfire Diagnosis

Misfire faults have been related to conditions like loose/damaged electrical connections, poor circuit grounds and more.

Models

All Models (Except Routan) 2008-2017

Description

Customer may state that the MIL is flashing or illuminated. The engine performance may be reduced without a significant loss of power or a consistent misfire condition. One or more of the following DTCs are stored in the ECM fault memory:

• P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P130A

Misfire faults have been commonly related to conditions such as loose or damaged electrical connections, poor circuit grounds and/or poor fuel quality. 

  • There can be multiple causes for engine misfire, ensure all campaigns and applicable technical service bulletins (TSBs) have been performed.
  • Repeat repairs must be carefully addressed to identify the root cause of the concern. Utilize proper diagnosis steps to ensure that the concern has been identified, the vehicle is repaired properly and that the repair is verified.
  • To repair the vehicle correctly, obtain as much information as possible from the customer about the symptoms of the condition and when it occurred.
  • In what situation (turning, acceleration, rolling stop, etc.) does the condition occur?
  • Under what environmental conditions (road conditions, weather, temperature, start conditions, etc.) does the condition occur?
  • What is the operating situation of the vehicle (activated electrical equipment, gear selection, etc.) when the condition occurs?
  • Can the complaint be reproduced?

Repair

1. Read out the data memory of engine control module and note the environmental conditions on the DTC log.

  • If there are other entries in addition to combustion misfires, address the other entries before addressing the cylinder misfires.
  • If DTC P0301-P0308 (Cyl. 1 misfire detected-Cyl. 8 misfire detected) is accompanied by P1250 (fuel level too low), it is likely the faults occurred due to low fuel level, and not a component malfunction.

2. Try to duplicate the customer complaint based on the environmental conditions at the time the DTC was set. The freeze-frame data gives important indicators for the traceability of the complaint, in particular, if it occurs sporadically or at cold start.

  • If cylinder misfire faults are sporadic and a P130A Hide Cylinder fault is not present, it is likely that the misfires may be caused by poor fuel quality and are not related to a faulty component.

3. Observe the requirements of Guided Fault Finding. Perform Guided Fault Finding in full, according to the proposed sequence (test plan). DO NOT skip any steps.

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