I finally got my car to startup and it was a bad trottle position sensor,when it started up there was a loud rattle so I cut it off and checked the oil level and it was 4 quarts low. After putting the oil in the noise went away until I started driving it. Can anyone tell me what is going on and how serious is this problem .The car is a 89 Grandprix. Thanks for any help
4 quarts low is really bad chances are you have some engine damage.the question i would ask though would be where did the oil go?if your losing oil too fast you might end up killing your engine try to find out where its going and if you can fix the problem and then move on to your rattling problem.
If he's lost that much oil chances are the rings/bores are pretty worn.
Rattle on startup is probably subsequent piston slap.
Compression test taylor and start saving.