Last week I went out on my 91 octane tune running 17 psi. The opportunity came up for some races, so I swapped out the pulley for a 19 psi one and when I went to swap the tune out w/ my XCAL 2 the XCAL stopped half way through. Now this happened once before, end result I had to buy another PCM. It may had something to do w/ the battery not putting out enough voltage. I know guys pull the fan fuse/rlay so it doesn't add a drain on the battery. Well, I got luckey on this one. I disconnected the battery for about 10 mins (that's how long it took to get a replacement) and installed an almost new Optima. Re-wrote the tune and everything was fine. Oh I left out that after the tune failed to write the first time, the dash/ odometer read out had dashes across it. anyone else had this happen to them before? Is it a common think linked to the battery?