I'm using tunercat, change my tire size/rear ratio, turned of EGR, and changed the TCC tables to not allow lockup in 3rd. Now the tach doesn't work, and the speedometer spazzes out, it will flop between 110-150. At slow speed it makes a buzzing noise and the odometer goes flying.

The ECM knows the correct speed and RPM however, I've checked it with datamaster.

Any ideas? I'm pretty new to tuning so I'm stumped.

Ohh I dropped in a spare ECM and it all worked fine, then I dropped that bin file on it and it started spazzing again, so it's something with the file.

 

I have heard, but not confirmed, that the speed calibration stuff with the Tunercat software can be problematic. Many PCM tuning professionals will use a different software package for modifying the speedo calibration.

What gears are you running and are your tires stock height?

 

I went from 2.73 rto 3.42 and running 315/35/17's I think the problem now is even if I program it back, it won't work properly. I may drop the stock tune back on and start tuning all over again, at least those two worked.

 

Double check that you have the right transmission (A4 or M6) and platform (F-body) selected in Tunercat.