Low RPM shudder/vibration at 1000-1200 RPM, most noticeable around 60-70 km/h (primarily in 5th gear for automatic transmissions) when going uphill or under slight load. Some experience the shudder when the vehicle is in park or neutral while on an incline. Some have also experienced it in reverse.
Solution
Replacing faulty fuel injectors is the primary solution to eliminate the shudder. Cylinder 6 injector issues were specifically mentioned in one successful case. Other potential remedies and diagnostic steps include:
- Transmission Service: Flushing and replacing transmission fluid.
- Intake Cleaning: Using a Subaru upper engine cleaner.
- Spark Plug Replacement: Check for water stains or corrosion near coil packs, indicating potential water ingress. Look for loose spark plugs.
- Coil Pack Inspection: While less common, a failing coil pack can contribute to the issue, although mechanics report them to be very reliable.
Parts
- Fuel Injectors (Recos were used in one successful repair)
- Spark Plugs
- Castrol Transmax FE Transmission Fluid (approximately 10 liters used for flush)
- Subaru Upper Engine Cleaner
Diagnostic Steps & Checks
- RPM vs. Speed: Determine if the shudder is related to a specific RPM range, regardless of gear.
- Gear Dependency: Does the shudder occur in all gears at the same RPM, or is it isolated to a specific gear (often 5th)?
- Load Sensitivity: Does the shudder only occur under load (e.g., uphill)?
- Transfer Case Dampers: Check the condition and tightness of dampers on the back of the transfer case. Note that there may be empty threaded posts for additional dampers.
- Visual Inspection: Inspect engine and exhaust mounts for damage or looseness.
- Air Flow Meter: Clean the air flow meter
- Fuel Filter: Replace the fuel filter
Potential Contributing Factors
- Torque Converter Lock-Up Clutch: Slipping of the lock-up clutch in the torque converter has been theorized as a cause.
- Transfer Case Imbalance: A balancing problem within the transfer case.
Additional Notes
- The issue appears to affect both petrol and diesel engines, as well as automatic and manual gearboxes.
- The vibration sometimes increases slightly in speed over time.
- Some have noted the problem is less noticeable when the engine is cold.
- One user noted there are different part numbers for the torque converter and one may be more prone to problems.
This technical summary was auto-generated based on recovered archives. Do not rely on its factual accuracy. Refer to the original thread. Source: View Original Conversation
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