I have a 98 f3 was cruising to work a week or so ago and my tach quit working at a red light. So i drove for a few weeks just guessing the rpms by sound and decided to get a f4i guage since apperantly you have to replace the cluster if anything goes wrong so i swped it with the f4i guages which look awesome and were easy to install but my tach still doesnt work it will spin when you put the key in but work rev up with the engine. The only thing i have tried to solve this problem is replaceing my guages does anyone have any suggestions on what else it could be. I cant find anything in my clymer manual for this and havent found any threads on this. How are the rpms measured? is there a sensor or something that could be shot. Its driving me nuts having these sweet guages and the rpms dont register.

 

any ideas fellas 25 hits no posts

 

There is a sensor/pulse generator, which could be your problem.