Here's why:
* Transmission Fluid and Engine Interaction: While the transmission and engine are separate systems, they are interconnected. A malfunctioning transmission, particularly one with very dirty fluid (containing debris that can clog valves or sensors), can put undue stress on the engine. This can manifest as rough idling and hesitation, especially if the transmission's control system is sending faulty signals to the engine computer (ECM/PCM).
* Torque Converter Issues: Dirty fluid can damage the torque converter, which is a crucial part of the automatic transmission responsible for smooth starts and idle. Problems here can directly impact engine behavior.
* Transmission Sensors: Dirty fluid can affect sensors within the transmission that communicate with the engine control unit (ECU). Faulty sensor readings can lead to erratic engine operation.
Important Note: While dirty transmission fluid *can* contribute, it's more likely a symptom of a larger problem within the transmission itself or a related sensor issue. Rough idling and hesitation are often caused by a variety of factors, and it's rare for only one to be responsible. You'll likely need a proper diagnostic check to identify the root cause. A mechanic should check the transmission fluid condition and potentially perform a scan for any diagnostic trouble codes (DTCs).
