2005 Fails to reduce RPM on shift 1st to 2nd
My 2005 4 banger frequently refuses to reduce engine speed to compensate for change in gear ratio during shift up. Car surges forward at ever increasing speed until shifted to neutral and all system turned off. Just killing the engine DOES NOT reset the ECU to controlled operation. What's at fault? Xmission input shaft rpm, xmission output shaft rpm, input/output difference, idle speed motor, ECU internal circuits? Now being worked on by second Hyundai dealership.
BTW, ECU has never set a code in over thirty episodes with my wife or me driving. First dealership tech alleges a code was set in a single test drive by him and required replacement of Idle Actuator Assy. That did not fix the problem. Hyundai Corporate has taken control of the situation.
Any thoughts? Ever heard of this before?