Smog

Yup so I failed it today. Had to get a software update from the dealer (some recall that the person before me never took care of). After that I took it to get smogged. Made sure it was nice and warm and put 91 in it. No luck tho.

1996 4.0

NO (PPM)

15 MPH max 527 meas 570
25 MPH max 780 meas 276

Any idea how to bring it down?

This is what I have done.
new plugs and wires
new cap and rotor
new fuel filter
Just changed the oil
Did the sea-foam thing a few tanks ago.

Could be a few things but I would guess a new cat would solve it. I guess you could clean the EGR but I doubt thats the root of the issue. Faulty oxygen sensor could be causing too lean a mixture. Umm I dont know Im no emissions expert, just some ideas.

If you want to try that "guaranteed to pass smog" stuff you might get away with it since you're so close to passing. It's only like $10 dollars or so I think, but Ive heard that it works. Good luck.

Mine failed with NO at 867/636. Passed after new cat with 86/147.

he just put new o2 sensors in it.

my vote is a cat as well. get a price locally and let me know Jon, i'll see if i can beat it through my work.

htwhite said:

Could be a few things but I would guess a new cat would solve it. I guess you could clean the EGR but I doubt thats the root of the issue. Faulty oxygen sensor could be causing too lean a mixture. Umm I dont know Im no emissions expert, just some ideas.

If you want to try that "guaranteed to pass smog" stuff you might get away with it since you're so close to passing. It's only like $10 dollars or so I think, but Ive heard that it works. Good luck.

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After Renix, on the 4.0L the EGR was deleted. I'm sure the cat needs to be replaced anyways. But some isoprop alchy in the fuel tank can help too.