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

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

by in Gardena, CA on July 31, 2012
2 answers
ANSWER by on August 01, 2012
did you ck egr passages while valve was off they plug
ANSWER by on August 01, 2012
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.)

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