Failed my smog test, what to do next?

[RYU]

Its pretty easy. First tine could take 45 min depending on how tight the bolts are on there. It really is simple, all u need is a 14mm wrench and ratchet or what ever size it is again.

And i know this is a little off but we have 4 02's correct? I ask cause everyone talks about tbem going out or the car running rich or lean but my headers are stock but i use anti fouler mod for sensors in the straight pipes. How will this affect the rich lean stuff? Anyone else doing this for ur set up?

Earlier NSXs have 2 pre-cat O2 sensors. Later cars have 4 (2 pre-cat, 2 post-cat). I believe the cutoff was the time the switch from OBDI to OBDII was made. I've never owned a OBDII NSX so I someone here will have to verify. I know I definitely have two.. and you definitely have four. Its not surprising that by removing the cat it could throw off a CEL from the rear 02s.

Not sure if this helps but in my LS1 OBDII Chevelle I had to reprogram the ECU to ignore the rear pair post-cat 02s. It was strictly for emissions control. Wasn't for the fuel map.

EDIT: I think OBDII started in 95+ not to be confused with NA2s starting at 97+. The info is on prime somewhere

 

[SuperSonic]

My mind must have been else where yesterday lol. I forgot the rears were just for emissions, thats why i stuck them in antifoulers

 

[SoCalDude]

Dropped my car off with Ramon today. He looked at the numbers and thinks it may be the O2 sensors. Getting all the maintenance stuff done with him this week and hope to pass the test after that without replacing the cats.

 

[SoCalDude]

So after new spark plugs, O2 sensors, oil change, air filter change, guaranteed to pass, I FAILED AGAIN! Look at the numbers for the 15 mph. It's even worse than last time before the service. Unbelievable!

 

[lithiumus]

Emissions is a finicky thing and many things could be at play. IMHO if the mechanic that you are going to does NOT have an emissions dyno / 5 gas analyzer so that they can get direct feedback, it's just going to be trial and error.

Everyone can have an opinion and guess at what could be wrong. The numbers will suggest a general direction but unless your car is hooked up to a live emissions dyno and you can for example, pinch the PVC and see the effects on the emission output or swap the cats and see the results with certainty and be able to pinpoint the problem...

It's just a guessing game via trial and error... and the only person who is going to pay the price is you. The last thing you want is to spend a bunch of money replacing "suspected" parts only to go back and forth to the emissions testing and your mechanic trying to fix the problem.

In Canada there is a service limit of something like $450. i.e if you spend $450 and still don't pass, they will give you a pass anyway but you have to test again next year. You could end up spending $450 every year until you figure out what the issue is...

Ideally, you want to bring it to someone (your choice) who is able to "guarantee" that they find the problem. Only way to do that is have emissions feedback while troubleshooting. At least the OBD2 cars have more diagnostics to ensure all components are working. OBD1 cars are not so lucky. If you have an emission problem and no CEL is coming on, it may be more difficult to pin point the root cause.

Sorry to pull up my own post, but I was really trying to save you some time and money when I wrote it... I'm assuming that Ramon does not have an emissions dyno / 5 gas analyzer?

Without accurate feedback, you are going to continue down the path of trial and error. Find someone who can actually measure your emissions output while testing and swapping parts so you can (as best you can...) guarantee a pass...

 

[NSXclear]

Did you reset the ECU before the smog?

I always reset the ECU right before a smog check. I make sure I let it idle for about 15 minutes, then drive around for a few miles normally to let the ECU relearn.

Do you have the stock ECU? Is is mod or chipped?

 

[SoCalDude]

Find someone who can actually measure your emissions output while testing and swapping parts so you can (as best you can...) guarantee a pass...

Not easy to find.

 

[SoCalDude]

Did you reset the ECU before the smog?

I always reset the ECU right before a smog check. I make sure I let it idle for about 15 minutes, then drive around for a few miles normally to let the ECU relearn.

Do you have the stock ECU? Is is mod or chipped?

I would think Ramon would have done that. I showed him the smog test when I brought the car. It's a stock ECU. BTW, How do you rest it?

 

[Malibu Rapper]

I would think Ramon would have done that. I showed him the smog test when I brought the car. It's a stock ECU. BTW, How do you rest it?

Pull the clock fuse for 10 seconds. you will lose your programmed radio stations and clock setting.

 

[ss_md]

Pull the clock fuse for 10 seconds. you will lose your programmed radio stations and clock setting.

I know if you reset the ECU or the battery dies on an OBDII vehicle you need to drive the car for at least 200 miles for the ECU to reacquire measurements before taking it back for the smog test, does this apply to OBDI?

 

[NSXclear]

I know if you reset the ECU or the battery dies on an OBDII vehicle you need to drive the car for at least 200 miles for the ECU to reacquire measurements before taking it back for the smog test, does this apply to OBDI?

I just did a smog on two 91 NSX (ODB1) this month and reseted the ECU before I took it to smog. The smog place was only 10 miles from me. I did let it idle for 15 minutes, before I started to drive it. I passed easily, even with the stricter emission numbers.

So the answer to your question is:
NO, you do not need to drive it at least 200 miles for the ECU to relearn for OBD1

 

[Hapa88]

How warm was the car when you tested it the second time? Did you drive it a good 20 minutes beforehand?

 

[BATMANs]

So after new spark plugs, O2 sensors, oil change, air filter change, guaranteed to pass, I FAILED AGAIN! Look at the numbers for the 15 mph. It's even worse than last time before the service. Unbelievable!

spark plug gap correct?

That made a difference for my last smog test.

Do a compression test. If that checks out OK, I'll say that the cats are old and probably worn out.

 

[SoCalDude]

How warm was the car when you tested it the second time? Did you drive it a good 20 minutes beforehand?

It was warm Drove it on the freeway for a bit first.

 

[SoCalDude]

Pull the clock fuse for 10 seconds. you will lose your programmed radio stations and clock setting.

I think I should try this. Where is the clock fuse?

 

[Malibu Rapper]

I think I should try this. Where is the clock fuse?

Under the hood in the fuse box.

 

[FelonyRuckus]

drive the car hard!! also, don't let it cool off...seriously, the cats will do better for you at very high temps but, cool off very quickly.

Also, I believe that OBDII its a minimum of driving 85 miles if you reset the ECU otherwise it will show a soft CEL on the smog computer when they hook it up.


I still think you should borrow someones cats or buy some used ones...

 

[ss_md]

Gene,
Did you get your NSX smogged yet?

 

[Prospeed]

you could always try replacing your cat's with a set of hi-flow cats and call it a day? hehe jp But seriously seems like you did everything else except replacing the cats. Go OEM or aftermarket. :smile:

 

[nsxotic911]

On my trashed Civic by the previous owner <tsk> <tsk> I tried everythign and nothing worked until I put in some RXP... http://www.rxp.com/

 

[SoCalDude]

Gene,
Did you get your NSX smogged yet?

Not yet. May try again this weekend. I did pull the fuse but need to put a few more miles on it.

 

[SoCalDude]

you could always try replacing your cat's with a set of hi-flow cats and call it a day? hehe jp But seriously seems like you did everything else except replacing the cats. Go OEM or aftermarket. :smile:

I may do that a some point. Any way to test if the original cats really are bad?

 

[SoCalDude]

On my trashed Civic by the previous owner <tsk> <tsk> I tried everythign and nothing worked until I put in some RXP... http://www.rxp.com/

I did put in Guaranteed to Pass. Is this stuff any different?