The engine makes a chirping/grating sound while idling, sound goes away while accelerating. What could be wrong?
Most likely, you are hearing the noise of a belt (“drive belt”, “serpentine belt”, or as we called them in the old days, a “fan belt”) that is loose. However, that is just a guess from afar.
Have a mechanic check this situation for you and determine if you need a new belt, or if the tensioner for the belt is bad, or both–or if it is an entirely different issue. It is far better to have this remedied in a timely fashion than to be stranded on the road when a belt snaps or when another problem becomes critical.
I Don’t Know An Acura From Dracula (No Acuras Here), But . . .
. . . I do see that they made some 2002 MDXs with defective timing belt auto-tensioners that could leak oil (oil is in there to dampen oscillation) and cause engine noise. What the engine noise sounds like I don’t know.
This car is 9 or 10 years old, a senior citizen in car years. Way back in history (2003) owners were notified if their car needed updating. Are you the original owner ?
If you can’t find the noise then check with a dealer. They have information to determine if this vehicle was built with a defective part and whether or not it was updated.