Although you may think that you are clearly stating the problem, I will point out a number of reasons that a Nissan Sentra will not start:
- No key in the ignition.
- Key placed in the wrong hole.
- No gasoline in car.
- Wrong key in the ignition.
- Attempting to start the car using the power of your mind.
I'm fairly sure that none of the scenarios above apply to your circumstance but, without a more thorough explanation of the circumstances surrounding the failure of your Nissan Centra (of unspecified year and engine) to start as you would like.
Please state the YEAR of your Nissan Centra, as well as which ENGINE it has, and please describe the circumstances under which the failure occurs, as well as stating any precursors to the failure, and any insights you may have as to conditions which may have caused it (such as "car has been running rough since 1989" or "drove the car off a cliff recently and the battery exploded).
Once you provide a thorough explanation of the problem you are trying to solve, I'm sure that if I'm still clueless about the issue, someone else will be able to answer your question.