My EGR valve is bad, diaphram is stuck, and I believe my CAT is bad as well. I have the new catalytic converter here and I still need to order the EGR. My question is, will the bad EGR damage the new cat if I go ahead and put that on first?

 

im gonna go ahead and say no on that one

 

Ditto. Put the cat in. Dosen't matter either way.

 

Really? Hmm, the bad EGR makes the car run rich, so I was thinking that might hurt the car...

 

For a fairly short period of time I don't think it will mattrer.