I suggest you check the message part of Pc Lap Counter, you should see message about pacer speed adjustement.
Also, you forgot to tell us some important informations:
- Which version of Pc Lap Counter ?
- With which track systems (oXigen, Scalextric C7042, etc...) ?
- In the options screen, what did you specify in the gap range for the speed adjustement ? (default is 0,100 and 3,000)
More information on Pacer/Ghost car here:
http://www.pclapcounter.be/ghost_car_-_pacer_driver.html