1995 Chevrolet Blazer Q&A

1995 Chevrolet Blazer Question: won't pass smog high NOX mildy rough idle when warm

new egr-cat-O2-injectors sensor-MAF-good fuel pressure-vacuum-distributor- no diag codes- 6 months ago had O2 code and MAP code- replaced both -
Answer 1
did you ck egr passages while valve was off they plug -
Answer 2
AFTER you check and clean the EGR system , some other things to check would be ; engine temp.(195-210F) , make sure fan clutch is operating properly , IF it was an aftermarket cat. make sure it is in the original location and proper size I know CA. laws diff. from fed.. I do emissions inspections in VA. and I've seen many aftermarket cats that are 'legal' to sell , and supposedly meet 'specs' but can't clean up the exhaust the way a factory one would. Make sure your dist. timing isn't advanced to much. Check that the advance is working properly. If it's a high mileage engine, excessive carbon build-up on the pistons could cause high NOx.I believe GM has a 'top engine' cleaner for that issue- when used as directed I've seen good results.PLEASE , check the EGR first.(hint on the converter- if you have access to an infra-red thermometer you can check the cats temp and some of the other things mentioned.) -