I have a S5 which has started funny since I bought it. While you are cranking the car it will not fire but when you release the key from crank position it will most times catch and start to run. I also have a code for the trailing coil which seemed to test bad so I replaced it but I still have intermittent code and intermittent loss of tach. It has stopped idling now too. I am at a loss and almost want to say its the ignition switch but I am not sure. Thanks for any help.