I was reading how if your battery dies, aem needs to be synced again.

 

Not that I have ever known, can you stick this information in the thread here to ensure you aren't being misinformed some how?

 

Wow i pull the battery all the time and never sync. Post up that info...

 

The AEM does not loose its memory if the battery is disconnected. My car sat without a battery or a motor in it for 2 months and it fired right up after it was put back together

 

assuming you are talking about ign sync then no it will stay in the ecu without power.

When you go to ECU-setup-ign all you're doing is changing the ign sycn value under

ign-ign phasing-options-ign sync

that value is your sync value...should you change cal files to an old one or something else just copy/paste that value (assuming nothing mechanically has changed) and you will be sync'd