Expert: Sean Halliday - 1/10/2007

Question
Sean
Have a 2002 Tahoe flex fuel 5.3 l, vehicle sits outside in Minnesota. Started and idled normally until outdoor temp went below 32 degrees. Starts great but, within 10-15 seconds it drops to a very low rpm idle and idles rough until warmed up 3 minutes or so.The colder outside temp, the more rough it idles. Had idle air control replaced, did not help. Cleaned intake, did not help.
No check engine light has ever come on during this time.
Just for fun, plugged in block heater ( which had never been used before)last night 1/10/07. This morning it idled normally.
So finally, is it some sensor then that is not working? And where is it?
Thanks!
Steve

Answer
No,there isnt a sensor it is the fuel actually starting to freeze.32 degrees is freezing point and believe it or not gas will freeze up.I have seen this problem and the solution is what you have,a block heater.Sometimes the fuel will freeze in the lines and have to be thawed but its really extreme conditions that do this.So keep using the heater until the weather gets warmer theres nothing wrong with your car.