1991 Pontiac Sunbird emissions high NOX

1991 PONTIAC SUNBIRD
110,000 MILES • 6 CYL • FWD • AUTOMATIC
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JOHN MURPHY1956
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Ive had a problem for several yrs passing emissions on the hi NOX. replaced the EGR, two cats, barely passing each yr. All other emissions co2 HC are great and mileage is 24 mpg city no prob there.
NOX is 2X max. I have not replaced the o2 sensors they are OEM i think.
any ideas are appreciated!
JM
Dec 30, 2009 at 11:00 AM
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DOCFIXIT
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Nox is caused by high cumbustion temps. The EGR recirculates burnt fuel to low temp. EGR is faulty or passage ways carboned. The sloe purpose of EGr is to lower Nox
Dec 30, 2009 at 4:27 PM