I am doing project in which I need to estimate weibull parameters for car part failures ( I know data follows weibull ). I have 1000 cars data (part failure data). Now the problem is suppose some part fails after 6 year( from date of manufacturing) . But i have data of only first three year. Now in this three years data this particular part may have failed in very few cars. Since I am taking miles driven as cycle to estimate parameters. So all the samples( very few) I am gonna have will be less than some threshold.So when i estimate parameters based on these sample. It gives me wrong results. Can anyone help me how to do this.