Q45 failed state emission test for Nitrous Oxide

[BHurvitz]

My 1991 Q45a with 127000 miles failed the CT emission for Nitrous Oxide. The acceptable level is 778 and I scored 1000. The car has new plugs and runs well. Any ideas on what is wrong, or how I can find the problemThanksBob

[Q45tech]

EGR system not functioning as brand new...........EGR flow is low or non existant. Clean it up and out.

[BHurvitz]

Does anyone have any instructions on the procedure to clean or relpace the EGR system. What parts are involved. Which parts are known to be dirty. What can be cleaned and what needs to be replaced. Are any of them known to get stuck and brake due to age when they are removed.RegardsBob

[DAEDALUS]

The EGR gasket should be the only thing you need. You need to remove the EGR tube from the manifold, this is often completely blocked with carbon crud.