Start with the engine and use
Send registration, engine code if known, factory output and gearbox. TDI cars and vans span different turbo, controller and transmission generations. Explain whether the goal is daily response, motorway use, towing or a loaded commercial duty.
Separate low performance from a fault
Warning lights, limp mode, unusual smoke or a new lack of pulling power should be described before tuning is chosen. Include scans and boost, airflow or aftertreatment work already completed. A calibration is not a substitute for diagnosis.
Be clear about current software
A used car may already have modified software or earlier control-unit work. State what is known and preserve any original file. Unknown programming can alter the scope needed to establish a suitable starting point.
Include the drivetrain condition
Tell us about clutch, flywheel and DSG servicing or symptoms. A progressive torque brief can be discussed, but condition still has to be assessed. Supported transmission software and an engine tune are separate operations.
Arrange the route around the controller
Exact hardware and software determine OBD or specialist access. Mobile suitability is confirmed alongside the postcode. If the ECU is already removed, explain why and keep the fault evidence for the team.