I just bought a 1992 Cutlass Supreme Convertible and it failed California Nox smog test. I am sure its the catalytic converter because it was sluggish at 50mph and was surging.
I changed out O2 sensor, Coolant Temp sensor, MAP, and evap canister...removed throttle body and EGR valve and all seem normal....
It looked like a new catalytic converter was put on 3 years ago, does anyone have problems with High Nox, running lean....3.1 L engines


There isnt adjustments on egr. I have found this particular year a California cat converter test case for my exact problem, but the paper never addressed how to correct the high nox other than going with a more expensive cat converter...
Do you have this problem with your exact year, smog emissions

 

I replaced the emissions parts, found ignition switch not moving to off position and floor shift handle sticking not allowing it to go into park..

Replacing the ignition switch is not difficult as it may seem. You dont have to remove the tilt wheel either and no spring tool, if you dont have locking steering wheel..like 92's dont have. Removing the tilt wheel spring will give access to prying out park sensor, a long plastic peice and a torq screw....

After getting a battery at walmart 48.00 for a 680 cc is pretty good deal, popped out the old stripped outbolts...easy to do, and reassembled everything.

I dummped a quart of AMAZING down the o2 port and let it sit for a week, and put a new o2 sensor in. I started it and was idling it, while soap bubles and grime came pouring out, I was purging air out of t-stat orfice....

When I revved it up, it stalled out, I did it several times...so , I allowed it to cool 30 minutes...tryed it agian and no stalling and ran fine...but after it warmed it stalled agian when reved up