EGR, relation to lean? Options

[6gcnoob]

guys i keep failing the emissions test. im good on everything but my NOx. Ive been told time and time again that its my EGR or cat.

i am running two cats one on the stock mani and one new one down below. i got fed emissions.

i am also throwning a CEL # 25, lean air/fuel ratio. does the EGR have any relation to this code. if my VSV or temp sensor for the EGR failed wouldnt i be throwing a code for the EGR. i applied vacuum to the valve itself and the engine stumbled and died like it should. i cleaned the injectors and filter too but im still getting the code and failing.

[enderswift]

id imagine that if the egr valve were stuck open, then that would be 'sort' of like a vacuum leak and thus cause a lean condition.

but if that were the case it should throw a code metioning ur egr... im not sure but thats my 2 cents

[dgbldr]

id imagine that if the egr valve were stuck open, then that would be 'sort' of like a vacuum leak and thus cause a lean condition.

No it wouldn't. Air contains 20% oxygen. Exhaust contains 1-2% oxygen.

The symptoms could be related. A lean mixture often produces excessive NOx. Could be EGR problem, but not likely. Does it fail at idle or part throttle?

Is it running closed loop? Any other symptoms? How does it drive?