There are a few signs that your car's fuel injectors may need to be cleaned or replaced:

1. Poor gas mileage: If you notice that your car is getting fewer miles per gallon than usual, it could be a sign of dirty or clogged fuel injectors.

2. Engine misfires or hesitation: If your engine is misfiring or hesitating while accelerating, it could be due to dirty or clogged fuel injectors.

3. Rough idle: If your car is idling roughly or stalling, it could be due to dirty or clogged fuel injectors.

4. Strange smells or exhaust: If you notice strange smells or unusual exhaust emissions, it could be a sign of dirty or clogged fuel injectors.

If you are experiencing any of these symptoms, it's best to have your car inspected by a professional mechanic. They can diagnose the root cause of the issue and recommend the best course of action.