i just put in 373s for my 2000 z28, and i set my tire size and gear ratio in the programmer. i let it run on a jack and after a few rotations of the tire the car will die. i took it off the jack thinking it was because the front tires werent moving, and i went to back it out of the garage and i backed up 25 feet or so and it died again, you roll foward about 25 feet and it dies. i put it in park and let it idle it stays running. and i put the brake on in drive and give it throttle and put a load on it but not moving it stays running. i take all the programs out and take it back to stock and the car runs but wont shift right and i know why. i just dont see why it dies when i put all the ratios and tire size in... any information? im clueless. thanks

 

maybe when you program your PCM with the new gear ratio the Hypertech is also putting his "tuned files" on the PCM
I know that the Hypertech program does change the timing, just can't remember if it was the Low or the HighOctane timing, so check the two timing tables and compare it before and after you write the Hypertech program to your PCM
I had the Hypertech programmer, didn't like it, got rid of it on ebay

 

The Hypertech will only put in the "performance tune" if you select "Yes" at that option. You can select "No" and bypass that useless feature. At least that is the way mine was.

 

ttt...