My 02 zx2 zetec has developed a light ticking when it's really cold outside. Anything below 32 degrees F it ticks. Ford told me that is was the computer advancing the timing to far causing spark knock, something these cars do regularly on cold days. Some have told me it could be a wrist pin or a rod or main bearing. Don't think it's in the engine though, cause it quits after 30 seconds of running. Any ideas or suggestions?