You asked: "Anyhow, will it cause any damage leaving it unplugged? Will the car start when it's cold without it hooked up?" The cold start valve only fires when the air temperature is below 95 F therefore the lower the temperature below 95 F the more difficult it will be to get the engine to fire. Other than that there are no ill effects to having the cold start plug disconnected. To return the cold start valve to its normal operation simple replace the Time-Temperature Switch, this procedure is easily accomplished in just a couple of minutes. The Time-Temperature Switch is part number 102462 and is priced at $38.40 from your favorite DeLorean parts supplier. DMC Joe www.dmc.tv "We're here to help you" DMC Help / De Lorean Services / <dmchelp@xxxx>