I have a 89 iroc with stock tpi. I have a custom piggy back chip for vats delete and to raise the idle other then that stock tune. I am using the tuner pro software to see what the engine is doing and when I am reading all the data there is like a glitch where all the numbers at the same time jump to a crazy number and then back to normal. It will do this evey 3-5 sec and I can hear a change in the way the engine is running that correlates with the numbers changing. Is this normal or is there something else going on

 

http://tunerpro.net/forum/viewtopic.php?t=2215