[steely]

if you are lucky, and the wire in the grommet that you are bumping into is the same one you are replacing, I would cut it and pull it from the engine side. You'll get a bit more room.

If it isn't, at least you will have one less cable in the grommet, and it (the grommet) will come out a bit easier.

For replacement, I found that cleaning the grommet and the firewall hole edges real good to eliminate any friction causing dirt - then use a water based lubricant to op the sucker back in.

in the future if you replace the CHT (white wire, it will come with a new grommet BTW.