* Lean Condition: The increased airflow from the cold air intake isn't being matched by a corresponding increase in fuel delivery. The ECU is still operating based on its original map, resulting in a lean air/fuel mixture in the 4000-5200 RPM range. This lean condition can cause hesitation, misfires, and potentially damage your engine if left unaddressed.
* Improper RVPM Calibration: The RVPM might be altering ignition timing or other parameters in a way that clashes with the increased airflow. It's possible the module isn't properly calibrated for your specific engine and modifications. Some RVPMs are notoriously problematic and may not be effective or even detrimental.
* Mass Airflow Sensor (MAF) Issues: The MAF sensor measures the amount of air entering the engine. The increased airflow from the cold air intake might be overwhelming the MAF sensor, leading to inaccurate readings and incorrect fuel delivery calculations by the ECU. A dirty or faulty MAF sensor could be the culprit.
* Air Leaks: The installation of the cold air intake might have introduced air leaks in the intake system. Unmetered air entering the system will throw off the air/fuel ratio, causing hesitation.
* Software/Tuning Conflict: The RVPM may be conflicting with the factory ECU programming. It is very unlikely that the additional intake is responsible for any of the hesitations, but more than likely the combination of both. The RVPM is more likely responsible for the engine hesitation, due to its potential interference with the factory calibrations.
* Spark Plug Issues: While less likely, worn or fouled spark plugs can exacerbate hesitation, especially under load in the RPM range you describe.
What to do:
1. Check for Air Leaks: Carefully inspect all connections in the intake system, ensuring a tight seal around the MAF sensor and the air filter. Use a propane torch (with the engine running) to check for vacuum leaks around these connections. A hissing sound indicates a leak.
2. Check the MAF Sensor: Clean the MAF sensor using MAF sensor cleaner (follow the instructions carefully). If cleaning doesn't solve the issue, it might need replacement.
3. Consider a Tune: The most effective solution is likely a professional engine tune. A custom tune will adjust the fuel delivery and ignition timing to compensate for the increased airflow from the cold air intake. This will optimize performance and eliminate hesitation.
4. Remove the RVPM (for testing): To determine if the RVPM is the problem, temporarily disconnect it and see if the hesitation disappears. If it does, the RVPM is likely the cause and you should consider removing it permanently or seeking professional help with its calibration.
5. Inspect Spark Plugs: Check the condition of your spark plugs. If they're worn or fouled, replace them with new ones that meet your engine's specifications.
Important Note: Driving with a lean condition can severely damage your engine. If the hesitation is severe, avoid driving the vehicle until the issue is resolved. Seek professional help from a qualified mechanic or tuner if you're uncomfortable troubleshooting the problem yourself.
