Output voltage is 14.37

 

That's good and so were the two readings you took from the coil check connectors. As stated earlier, you can have a poor connection to the tach. You can use the spare S5 tach and use the check connector at each coil to test the tach. You could also disconnect the lead coil while running and the idle should become rough. If the engine just flat out dies then that would lead one to believe the trailing coil is not operating properly and thus a poor coil/igniter which results in the tach not operating.

 

its been getting me to work and back and runs and drives great I just have no tach gauge lol so I might see about grabbin another s4 manual cluster... my title already reflects mileage tampering anyways rofl.

 

If you have a spare tach it would take a couple of minutes to tell you where your problem lies but it's you car so good luck.