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.

[Bitter]

yes, it will cause running problems if the egr is leaking one of which will be a slightly lean mix but not that much, more of an issue with the computer not knowing the egr is open and not making needed adjustments. at idle the vac is the strongest so it'll pull in more exhaust than it should and begin to run rough and stumble.


i agree that high nox can be caused by running lean, lean burns hotter, burning hotter can raise nox. but higher compression can also raise nox, it could be a carbon buildup issue or ignition timing issue.