talk to me about O2 sensors

[BATMANs]

My smog is coming up in a month.

110k~ miles on the original O2 sensors.

OBD-1

No check engine lights.

Should I replace it (OEM or aftermarket) or wait until the check engine light goes off?

 

[Briank]

If it ain't broke don' fix it.

 

[BATMANs]

If it ain't broke don' fix it.

I was thinking the same.

But do these O2 sensors start to degrade and become less efficient at doing their job before the heck engine light goes off?

California has reduced the allowable emissions by 30%.

 

[nsxnut]

What do the short term and long term fuel trims look like?

Worst case you will need to replace and bring it back for a retest.

 

[BATMANs]

What do the short term and long term fuel trims look like?

Worst case you will need to replace and bring it back for a retest.

I'm not following you on your question. Are you talking about having a "smog legal" fuel trim and one for performance?

This link will have the current AF ratios.

 

[nsxnut]

On an OBDII car if you scan it the short term and long term fuel trims should be Low values.
The computer should not be trying to pull allot of fuel out.

I am no expert.

You can also scan the O2 sensors.

A few years ago I failed smog. Mechanic told me to scan it and look at the fuel trims. Net result I had a marginal o2 sensor.
I replaced it and trims went back to normal and the car passed.

 

[BATMANs]

OK. I'm just worried about what happened to me in both my RX7 and truck years ago before the tougher smog standards (lowered emissions and dyno smog machines) where I failed the first time and was put on this gross polluter list to smog my car/truck EVERY year. Total PITA.

 

[DRIFTER]

OK. I'm just worried about what happened to me in both my RX7 and truck years ago before the tougher smog standards (lowered emissions and dyno smog machines) where I failed the first time and was put on this gross polluter list to smog my car/truck EVERY year. Total PITA.

Wow that sucks! Im glad NY isn't like that yet. Do they charge you every year?

 

[BATMANs]

Wow that sucks! Im glad NY isn't like that yet. Do they charge you every year?

Yes, I have to pay for the "test ONLY smog station to do their work.

 

[d.n]

The smog tech may be willing to do a sniff test first to see where you're at if they aren't busy. If you're passing or close you can then roll the dice. If not, then you can drive off and figure out what to do. This will save you from the gross polluter headache (I was under the impression they remove you from that list if you pass the next year without issue). It doesn't hurt to tip the tech.

 

[NSXclear]

CA has reduce the allowance for NOx considerably. This is where I see most NSX fail with the new requirements.

The key to getting the NOx numbers down is to clean the EGR and the passage pipe thoroughly. Mine was caked with carbon deposits. I used a soft pipe brush and seafoam to clean them out. My NOx numbers dropped over 80% after the clean.

Make sure you get the cats super hot, before taking it in for testing. Keep the car running and have the tech pull it into the bay immediately.

 

[02#154]

About these new emissions requirements...

So, a theoretical car that was bought new in 1995 (and therefore emissions legal for its day) and never driven once, would have to meet today's new emissions requirements to be legally operated in CA?

Something doesn't sound right.

J

 

[NSXclear]

Something doesn't sound right.

We live in CA. There is a lot about CA that isn't right and doesn't sound right :biggrin: ...where to begin!

 

[Daedalus]

About these new emissions requirements...

So, a theoretical car that was bought new in 1995 (and therefore emissions legal for its day) and never driven once, would have to meet today's new emissions requirements to be legally operated in CA?

Something doesn't sound right.

J

It's purely a numbers game and every car has its own requirements. A new undriven NSX from any year would have no trouble passing a sniff test. The cars that fail either have legitimate problems or they aren't tested properly. I'm pretty sure it's a statistical move, where the CARB uses past numbers to eliminate the worst x% of cars of each model/year. Keep this in mind when you hear about guys who pay off a smog tech to run a Civic in place of their NSX. That only makes it harder for all of us come the next year.