Ran my 1989 oldsmobile 88 out of fuel then added gas to start the vehicle. when turning the car over the engine started to make a noisy rattle sound. since that day the engine continues making that annoying sound during start up and at lower rpm's. i cannot determine for a fact where the noise is actually coming from. the vehicle is front wheel drive and it runs but the noise continues. i thank you for any help or advise you would send my way. i was told the knock sensor should be remove but i couldn't even tell you where it was located.