You are 1/2 right. The 93+ engine the ignition timing is not adjustable. On the 91 & 92 TT the timing is set by the crank angle sensor.Bret Brinkmann said:I'm assuming you mean ignition timing. Time for this is automatically set by the ECU. The ECU also automatically adjust it based on weather conditions percieved from sensors. Are you haveing some sort of problem with your idle or missfireing?