i recently took my 1992 buick regal custom 3.1 litre 4 door in for an E-test and passed all the requirements except for a high NOx ppm what can i do to fix this problem so it is completely passible for driving
High NOx means that your combustion chamber is burning hot.You could check your timing...do you have pinging? This could indicate a timing problem. Carbon deposits are possible too and probably the easiest to fix. You could de-carbonize the engine. This involves having someone inject a cleaner into the system, then taking the vehicle out for a drive and then changing the oil.
Make sure you take your vehicle only to a technician who is ASE certified. You can find one in your area by going here:
〉 Answered on Dec 15th, 2006 by Lori Johnson, Owner and Instructor at Ladies Start Your Engines