the reason i say its not the car is i had the same problem once. after racking my brain over several possibilities, i touched the black "box" module where the USB cord is connected and BAM! it picked up the signal. turns out the problem was in the USB cord and touching it with my hand increased its reception. often, just intereference can reduce the timing strip's ability to pick up the signal. i had to remove an extension i used on the USB cord while in other instances, it was just interference from other electrical items in the area. u can download a
IC Tag Lap Counter Support Document that has tips for increasing the sensor's ability to pick up the IC Tag.
note the IC Tag has no "signal" since its not connected to the power source in any way. its the same premise as a barcode scanner. most of your problems with IC Tag reception are going to come from your lap counter/lap counting software, not the IC Tag. i hope that helps
