Here are some possible culprits:
* Faulty Traction Control Module (TCM): While it seems counterintuitive, a malfunctioning TCM could be interpreting wheel slip even when TC is off, sending signals to reduce power. A faulty TCM might also be overly sensitive, causing the TC to engage aggressively even with minimal wheel spin.
* Wheel Speed Sensors: These sensors tell the TCM how fast each wheel is rotating. If one or more are faulty, the system might misinterpret data and react inappropriately, both cutting power when TC is off and engaging TC too aggressively when it's on. A bad sensor can cause inconsistent readings, leading to both issues.
* Transmission Problems: Issues within the transmission itself, such as a slipping torque converter or problems with the solenoids controlling shifting, could be contributing to the sluggishness when TC is off. The engine might be revving higher than expected while the car isn't accelerating as it should, which could be misinterpreted by the system as wheel slip (or even cause actual wheel slip).
* Throttle Position Sensor (TPS): A faulty TPS provides inaccurate information about the throttle position to the engine control module (ECM). This inaccurate data could cause the system to interpret the throttle input as potentially leading to wheelspin, thereby reducing power even when TC is off. This is less likely to be the *primary* cause but might be a contributing factor.
* Mass Airflow Sensor (MAF): Similar to the TPS, a malfunctioning MAF sensor provides inaccurate information about the amount of air entering the engine. Incorrect air/fuel mixture can lead to poor performance and the system might mistakenly assume wheelspin.
* Wiring Issues: Problems with the wiring harness connected to the TC system, ECM, or transmission control system could cause intermittent or incorrect signals leading to the symptoms you describe.
Troubleshooting Steps:
1. Have the car scanned for diagnostic trouble codes (DTCs): This is the most important first step. A professional mechanic or an OBD-II scanner can retrieve these codes, which will pinpoint potential problem areas.
2. Inspect the wheel speed sensors: A mechanic can check these sensors for proper operation and replace them if necessary.
3. Check the TCM: Testing the TCM can be more involved and might require specialized equipment.
4. Examine the transmission: If the codes point to transmission problems, a thorough inspection might be needed.
5. Check other sensors (TPS, MAF): If no other problems are found, these sensors should also be inspected as potential contributing factors.
It's crucial to have a qualified mechanic diagnose this issue. Attempting repairs without proper diagnostic tools and knowledge could lead to further damage or incorrect repairs. The symptoms indicate a sophisticated system malfunction, making professional diagnosis essential.
