92 NSX won't pass CA emissions

[snipesusaf]

Getting really frustrated, 1992 NSX failed CA emissions 4 times! <O></O>
<O></O>
Aftermarket mods that may affect emissions: DC headers and Comptech exhaust. Background, Shad at Driving Ambition did a 1996 motor swap last year and it's the first time I’ve smogged with new motor.<O></O>
<O></O>
First time: Check engine light came on (automatic fail). Shad checked and sure enough it was the O2 sensor, changed both out, problem solved? No.<O></O>
Second time: Emissions way too high, not really in the ball park either.<O></O>
Third time: Shad advised me to get my CATS really hot, so I drove around for a while at high RPM. Failed again, but this time it did much better<O></O>
Fourth time: Horrible decision... I let AutoZone convince me to put a "Guarantee to pass or twice your money back" BS solution in my gas tank, which SPIKED my numbers through the roof to almost gross a polluter!<O></O>
<O></O>
What are your thoughts?<O></O>

 

[TrustJDM]

Post your numbers so those knowledgeable are better able to diagnose possible solutions. Guaranteed to pass stuff isn't magic but does help on a few occasions. Requires a lot of driving to burn through a whole tank of gas only to refill again before the actual test.

 

[Rope]

Have you checked you IAT sensor and cleaned all the gunk off of it. That was the cause of another member failing.

 

[I1O101I]

Getting really frustrated, 1992 NSX failed CA emissions 4 times! <O></O>
<O></O>
Aftermarket mods that may affect emissions: DC headers and Comptech exhaust. Background, Shad at Driving Ambition did a 1996 motor swap last year and it's the first time I’ve smogged with new motor.<O></O>
<O></O>
First time: Check engine light came on (automatic fail). Shad checked and sure enough it was the O2 sensor, changed both out, problem solved? No.<O></O>
Second time: Emissions way too high, not really in the ball park either.<O></O>
Third time: Shad advised me to get my CATS really hot, so I drove around for a while at high RPM. Failed again, but this time it did much better<O></O>
Fourth time: Horrible decision... I let AutoZone convince me to put a "Guarantee to pass or twice your money back" BS solution in my gas tank, which SPIKED my numbers through the roof to almost gross a polluter!<O></O>
<O></O>
What are your thoughts?<O></O>

Can you upload the test results?


you might have to get new cats, and make sure you have a fresh oil change and clean your air filter before you go in again

bryan

 

[skafia]

More information about the IAT issue, I cleaned mine and I passed:

http://www.nsxprime.com/forum/showthread.php/159564-Is-your-NSX-failing-smog-Read-this

 

[snipesusaf]

OK here what my sensor looked like (one on the left)

 

[RaulGCustom]

great info on this thread

 

[snipesusaf]

cleaned with brake cleaner now. (Left) On one the right is my buddies car with the same amount of miles... why's mine so dirty

 

[snipesusaf]

Failed again after cleanig Air sensor... Here are the numbers. yikes

- - - Updated - - -

I'm serisouly thinking about selling.. this is frustrating. Im deployed right now, a buddy cleaned the air sensor for me. thought that fixed the prob, but I guess not. Its worse then ever. The car has been sitting for about 3 months on the old gas too. So maybe that caused the spike, I dunno.. any suggestions???

 

[cmthomson]

Looks like the cats were cold, or have failed. Before testing, be sure to drive a few miles, and leave the car running while waiting.

 

[NRG]

Unfortunately, I believe it's the seller's responsibility to pass the smog check in CA.

Good luck...

When a car is sold, who is responsible for the inspection?

The seller is required to provide the buyer with a valid smog inspection certification at the time of the sale or transfer. Smog certifications are good for 90 days from the date of issuance.

http://www.dmv.ca.gov/vr/smogfaq.htm#BM2537

I'm serisouly thinking about selling.. this is frustrating.

 

[shane91nsx]

If your car doesn't pass smog, can you sell it to a dealership or trade into something else instead of spending money to fix the car?

 

[g3driver]

I will buy your car. No worries about smog. I register as non op and use it for a parts / track car. Pm me

 

[I1O101I]

Failed again after cleanig Air sensor... Here are the numbers. yikesView attachment 104156

- - - Updated - - -

I'm serisouly thinking about selling.. this is frustrating. Im deployed right now, a buddy cleaned the air sensor for me. thought that fixed the prob, but I guess not. Its worse then ever. The car has been sitting for about 3 months on the old gas too. So maybe that caused the spike, I dunno.. any suggestions???

Have you tried an BG air induction service? that might clean up alot of carbon in the heads and valves, also check the EGR if it is working, take the EGR pipe off and clean it. also check the PCV valve. that the process I would start with.

I had the same problem passing emissions, when I found out it was a blown cat, it fail like 3 times.

Bryan

 

[snipesusaf]

A little more background... Factors behind my latest fail. Im deployed right now, a friend cleaned the Air sensor as suggested and took it to be smogged for me. The vehicle sat for almost 5 months with old gas, also the battery was disconnected in those 5 months. I'm thinking that didn't help my numbers improve from the last time 4 failures. The tech aslso couldn't find a 'carb legal' sticker on my DC headers, so he failed me on the visual inspection too. This was the first tech to look for this, they charged 83 bucks with NO retest too. Which seemed a little much, seeing I paid 40 bucks and got 3 free retests last time. but anyways, i'll check the EGR pipe PCV valve then retest. I have roughy 25K invested and LOVE my car, just be nice to drive it again :tongue:

 

[nis350]

In addition to cleaning the EGR pipe, do you need to also clean the port it attached to on the intake manifold? Are the gaskets on the EGR pipe reusable? thx.

Have you tried an BG air induction service? that might clean up alot of carbon in the heads and valves, also check the EGR if it is working, take the EGR pipe off and clean it. also check the PCV valve. that the process I would start with.

I had the same problem passing emissions, when I found out it was a blown cat, it fail like 3 times.

Bryan

 

[I1O101I]

In addition to cleaning the EGR pipe, do you need to also clean the port it attached to on the intake manifold? Are the gaskets on the EGR pipe reusable? thx.

I would just run air through the small pipes attached to the intake manifold, if there is no damage to the EGR gasket I would reuse it.

Bryan

 

[nis350]

so you remove the egr pipe completely and just run air to clean it? Will you be able to get all the gunk out with just air? I was thinking soaking it with brake fluid or carb cleaner....

Are those metal gaskets on both end of the egr pipe?

Thx.

I would just run air through the small pipes attached to the intake manifold, if there is no damage to the EGR gasket I would reuse it.

Bryan

 

[goldNSX]

We've comparable tests here in Europe (not talking of the east and the south ).

Get cats that are known for passing the Emission test and re-check. I even know of cars here (not mine) which passed smog with a lot of mods, exhausts, headers all systems and sport cats. Even a Random tech cat will pass and again we've strict tests.

Getting the cats hot helps but I've even passed smog with an semi-warm cat if it's in good shape. Yours seems to be shot.

 

[Vytas]

I'll throw something in here. Did you check the plugs? I had the same issue with a friend's 33K mile '91. After four tries, it failed the CA smog test. Ran Chevron Techron fuel system cleaner and it helped but not enough. EGR was clean, air filter clean, vacuum tests came out perfect and O2 sensors on the SnapOn diagnostic tool came up fine (but a bit on the lazy side). The O2 sensors were replaced and it helped but again, not enough to pass. With nothing else left to replace, the plugs were checked. They looked to be okay but replaced them with properly gapped Bosch platinums. What do you know? It passed! These plugs weren't that old but apparently they made a significant difference.

Here's another thing I discovered. Even though my '92 is the same as a '91, CA emissions have more stringent numbers for a '91 to pass than a '92. I compared my last report with my friend's and all allowable maximums were higher for a '92 thus making it much easier to pass. If these maximums were applied to my friend's '91, it would have passed. Why CA has tougher emissions for a '91 than a '92, with both cars being identical, is unclear. Was told by a shop that first year models always have tougher emissions standards but not 100% convinced.

Hope this helps.

 

[willabeest]

Getting really frustrated, 1992 NSX failed CA emissions 4 times! <O></O>
<O></O>
Aftermarket mods that may affect emissions: DC headers and Comptech exhaust. Background, Shad at Driving Ambition did a 1996 motor swap last year and it's the first time I’ve smogged with new motor.<O></O>
<O></O>
First time: Check engine light came on (automatic fail). Shad checked and sure enough it was the O2 sensor, changed both out, problem solved? No.<O></O>
Second time: Emissions way too high, not really in the ball park either.<O></O>
Third time: Shad advised me to get my CATS really hot, so I drove around for a while at high RPM. Failed again, but this time it did much better<O></O>
Fourth time: Horrible decision... I let AutoZone convince me to put a "Guarantee to pass or twice your money back" BS solution in my gas tank, which SPIKED my numbers through the roof to almost gross a polluter!<O></O>
<O></O>
What are your thoughts?<O></O>

suggestions and comments
1. no more techron in the gas - it can poison cats
2. reason NSX smog 1991 cut off is more stringent than for 1992 NSX is that there are way more 1991 NSX on the road, therefore a "bigger" problem.
3. generic cats are now CARB legal and way cheaper - you can buy them online. no idea if they are as good as OEM, but they worked for me.
4. the simplest, easiest, perhaps even least expensive way to pass smog is to drop off your NSX at your mechanic's garage and ask him/her to call you when the NSX is smogged.
combine it with an oil, filter change. life is good

 

[snipesusaf]

I'll drop it off at DA have have them check plugs and everything. He's a pro and sure could identify the problem quickly. Maybe even provide "loner CATS" for the day.
T

hanks for the input!

I'll throw something in here. Did you check the plugs? I had the same issue with a friend's 33K mile '91. After four tries, it failed the CA smog test. Ran Chevron Techron fuel system cleaner and it helped but not enough. EGR was clean, air filter clean, vacuum tests came out perfect and O2 sensors on the SnapOn diagnostic tool came up fine (but a bit on the lazy side). The O2 sensors were replaced and it helped but again, not enough to pass. With nothing else left to replace, the plugs were checked. They looked to be okay but replaced them with properly gapped Bosch platinums. What do you know? It passed! These plugs weren't that old but apparently they made a significant difference.

Here's another thing I discovered. Even though my '92 is the same as a '91, CA emissions have more stringent numbers for a '91 to pass than a '92. I compared my last report with my friend's and all allowable maximums were higher for a '92 thus making it much easier to pass. If these maximums were applied to my friend's '91, it would have passed. Why CA has tougher emissions for a '91 than a '92, with both cars being identical, is unclear. Was told by a shop that first year models always have tougher emissions standards but not 100% convinced.

Hope this helps.