Bad injectors can cause overheating. If the injectors are delivering too much fuel, the engine will run hotter than normal. The extra fuel will create more heat and also cause the engine to run lean, which can lead to pre-ignition and serious engine damage. If you're noticing that your engine is running hot, it's worth getting your injectors checked out. Injector problems are often hard to diagnose, so it's best to take your car to a mechanic who specializes in injector service.