98 XJ, i6, auto transmission.

I recently replaced my injectors and when I went to back out of my garage I noticed a fairly loud knocking when I am in reverse. The sound is coming from under and slightly in front on me. It does not clunk into reverse, there is no grinding noise, no popping while moving. If I put it in reverse, press the brakes, and increase rpms, the knocking increases in frequency but not in volume. The knocking noise is not present in any other gear, though I may have heard it when in drive facing down a steep slope.

I've tried searching for solutions but most of what I find has to do with shifting problems or popping while moving.

Any ideas about where to start looking?

 

Engine and trans mounts. I'd guess they're soft and loose and when in reverse the torque is making ske come in contact with the crossmember. Something like the exhaust.

 

Figured it out.

All my mounts were good. When I reinstalled the THOR intake I must have shifted it and the filter was knocking on the firewall.

Readjusted and it's no longer a problem.

 

Thanks for the update.

 

I think this noise is coming from my right lower control arm.

 

Odd place for a knocking noise. Easy enough to visually inspect though.