Thread: 2003 3.8 grand prix enigine noise

Well, since you have no history with the car it could be a lot of things. Because you had a mechanic say it was knocking, I would change out the spark plugs ASAP. I would personally use Autolite 605s in your position.

If that doesn’t work I’d move on to the MAF and MAP sensors.

Good luck.

i unpluged the maf and it still ran the same, i know there was a recall on some type of plug harness or somthing pontiac told me but they have a place only next week. shouldnt the engine knock at all times instead of only when i rev it up in neutral fast, and also while im driving when its starts hesitating and bogging u might hear it.