I have these two codes 171 and 174 keep popping up. I replaced the MAF sensor, PVC and the Air filter. Also checked out the vacuum leak by smoke testing by a professional mechanic. He claimed he could not find any leak. I am sure he did not check for the Plenum leak.

Can some one post a image of the plenum location on a 2001 Cadillac Sevilleso I can spray the starter fluid to check out the leak. I will appreciate your help.

Thanks in advance.