I want to know why it grinds when I put it in reverse and want Move.

Sometimes the reverse dog clutches fail on those. Do you have any codes?

Looks like a cat code with the P0420 and the P0171 is system too lean I dont see. P0170 code maybe you remembered or wrote down the wrong number.

Does it drive normal?Have you checked the axle yet?

They should be able to see if the axle is bad without removing the axle or taking it apart.

Saturntech9, some scan tools would show a P0170 when P0171 or P0172 is present.

If the axle is bad, you would not be able to drive at all.

Were there any crocking noise while making turns prior to this?

Symptoms indicates a possible wheel bearing failure.

The code thing makes sense some of the cheaper scan tools will read incorrect codes sometimes. As far as a bad wheel bearing I can't see that only allowing the car to go forward and not reverse. Also while driving forward it would make a lot of noise. Even the axle would I know the hondas have reverse dog clutches issues when they fail they produce those symptoms. Which the acura would fall into that honda catogorey. Use a long screwdriver to see where the noise is coming from.

When wheel bearings fails, thay can result in too much much side way movement of the rotor and this can get caught by the calipers. Moving in one direction is easier than the opposite. If a lower arm ball joint fails, it can cause the same problem as the axles would be stretched and this can cause the inner CV joint tripod to catch in one direction.

If it was wheel there should be a noise while driving especially if its that bad like say. Also does when you put it in reverse with your foot on the brake does it make noise denise12?