Experiencing a sudden jerk or hesitation when accelerating your 2008 Buick Lucerne, especially after applying heavy throttle, can be concerning. Many Lucerne owners have reported similar symptoms, describing it as feeling like a sudden jolt or a momentary loss of power. This issue often manifests more prominently when starting from a complete stop or in lower gears, and can sometimes disappear after highway driving or when the car warms up. Adding to the frustration, drivers often find that their OBD2 scanner reports no error codes, leaving them puzzled about the cause.
Several potential factors could contribute to this intermittent jerking and hesitation in your 2008 Buick Lucerne, even without triggering any OBD2 trouble codes. While the absence of codes might initially suggest the problem isn’t severe, it’s important to investigate thoroughly to prevent potential long-term damage. Here are some areas to consider:
Potential Culprits Behind the Hesitation:
- Transmission Issues: Although you recently had the transmission fluid and filter changed, transmission-related problems can still occur. Intermittent issues, especially in older vehicles, might not always immediately trigger diagnostic codes. Slipping gears or issues within the valve body could cause the described symptoms.
- Ignition System – Spark Plugs and Tune-Up: As you mentioned, a tune-up, specifically addressing spark plugs, could be beneficial. Old or worn spark plugs can lead to misfires, particularly under heavier loads like acceleration. These misfires might not be severe enough to set off a code immediately but can cause noticeable hesitation and jerking.
- Throttle Position Sensor (TPS) or Accelerator Pedal Sensor: While less common without codes, a slightly malfunctioning TPS or accelerator pedal sensor could send incorrect signals to the engine control unit (ECU) during throttle application. This could lead to a momentary fuel or spark delivery issue, causing a jerk.
- Fuel Delivery Problems: Issues with fuel delivery, such as a partially clogged fuel filter or a failing fuel pump, could starve the engine of fuel momentarily under heavy throttle demand. This could also result in hesitation and jerking, although fuel delivery problems sometimes trigger lean condition codes.
- Engine Air Intake: A restricted air intake, perhaps due to a dirty air filter, could, in rare cases, contribute to hesitation under acceleration. While less likely to be the primary cause of a significant jerk, it’s a simple maintenance item to check.
Next Steps for Diagnosis:
Given that you have an appointment scheduled, it’s wise to relay all the details of the issue to your mechanic, emphasizing the “jerking under heavy throttle” and “no OBD2 codes” aspects. Request a comprehensive diagnostic approach that includes:
- A thorough scan for any pending or historical OBD2 codes, even if the check engine light is off. Some advanced scanners can detect issues that haven’t yet triggered a fault light.
- Inspection of spark plugs and ignition system components.
- Checking transmission fluid level and condition, even after the recent service.
- Testing the throttle position sensor and accelerator pedal sensor.
- Assessing fuel pressure and potentially the fuel filter.
- A visual inspection of the air intake system.
By systematically investigating these areas, your mechanic should be able to pinpoint the cause of the hesitation in your 2008 Buick Lucerne, even in the absence of immediate OBD2 error codes. Addressing the issue promptly will ensure the continued smooth and reliable operation of your vehicle.
