How do I tell if my car has a bad camshaft or if it has a bad cam position sensor? When I first start the car it runs kind of rough doesnt die just lopes a little. once it levels out it is pretty quiet very little valve noise, but as soon as it gets RPM's it ticks. I dont have any problems with the car other then that it runs perfect when warm and starts up every time. it just struggles the first time you crank it over.