CALIFORNIA SMOG SPECS

[apu8883]

Starting a tread on CA Smog limits. I am hoping owners would put up pics of their results so we can figure out reasons and fixes for smog fails.

Car year, model, miles, etc.


I bought the car out of Colorado and I had to put the exhaust back to oem. Got cats from ebay with unknown number of miles and failed smog.
Got a second pair of cats from a forum member and passed smog.



1995 MT with 60,000 miles. The forum member had indicated 104,000 miles on the cats that passed smog. The emission difference is striking.

 

[drew]

FYI the limits have become more restrictive over time.

CARB in their infinite wisdom aggregate the data and will start reducing the limits over the years as they see certain models generally pass well under the existing maximums.

I have yet to find a place that rebuilds cats....

 

[Old Guy]

I have yet to find a place that rebuilds cats....

Given the value of the guts, I think they all get rebuilt; but, by a more circuitous process. The guts get removed and then processed to reclaim the catalysts which then end up getting put back into new catalytic converters.

Back in the early '90s I remember making a business trip to a local steel mill. All of their input was reclaimed metal, a lot of which was vehicles. As I walked from the parking lot to their offices I remember looking over and seeing a small mountain of catalytic converters. I was told that whenever the pile got big enough a specialist recycler would come in with a semi and load them up and take them away. Even 30 years ago the guts had enough value that they would take 5 minutes to roll the vehicle over and take a torch to cut the converter out before sending the rest of the vehicle into the shredder and then the furnace.

 

[apu8883]

I wonder if cats would just get more and more expensive over time, not necessarily due to the precious metal getting more expensive but because there are fewer being made due to ev adoption.

Would still like to get another spare set.

 

[sid619]

I had just gotten my car last month and took a few tries to pass smog. One thing I will say is, take it somewhere that has done the car before. The first place I took it had me help do almost everything since they did not know where a lot of the parts where (which should have been a bad sign from the beginning) this is the failed first picture. The place that passed my car, did not have any questions, and about 30mins later came out with a passed test, the first picture. Seems like they ran the test at slightly different rpms at 15mph, and had different pass not pass reason on the ignition timing, no idea why.

the pass fail values are lower on some and higher on others

I am in San Diego btw

anyways hope this helps people

Failed



Pass

 

[apu8883]

Since the test had to be in rollers, the tech asked me how to turn off the TCS. The tech did ask another mechanic how to clamp what I assumed to be something related to the a vacuum tube.

Since there are two exhaust paths, I think if you don't pass with one, might want to try the other. Also, how far the test tube is inserted seems to matter. Your NO seems high relative to mine but well within the pass range.

 

[apu8883]

So many weird things comparing yours and mine. The rpm at 15 and 25, the max emission for each test, etc. Seems to be a crapshoot other than grossly failing.

 

[sid619]

Yeah it’s bizarre, nonetheless in 2 years I will be taking it to same place that passed this time and hope my I don’t roll craps haha

 

[Old Guy]

Since it is NO that you failed on. Two factors to consider

If you look at the RPM, they are clearly doing the 15 mph test in a different gear on the second test. @MotorMouth93 might be able to partially answer this because he might be familiar with the EGR control maps. You can't do a definitive answer without knowing the MAP value during the test; but, if 1500 RPM is at the bottom or just out of the EGR operating zone then that may be a partial explanation why the change from fail to pass with the higher RPM.

I recall a number of years ago that some guys were 'doing things' with the EGR valve vacuum lines to insure EGR opening during the tests because the testing regimen was not getting the cars reliably into the EGR control zone. Another factor you might want to consider is how plugged up is your EGR system. The EGR valve may be opening; but, if the pipe into the intake manifold is crudded up you may not be getting the required flow at low EGR lifts. The OBDII system on the NSX monitors operation of the EGR valve to confirm that it is opening as much as it is being asked to open. Unfortunately, if the pipes are crudded up that does not mean that the required amount of exhaust gas is flowing.

The second factor is the temperature of the catalytic converters. On the first test if the 15 mph test was done first before the converters were up to operating temperature then conversion efficiency will be poor. Experienced smog techs will know that on vintage cars this is a problem. Later cars have strategies to get the cat up to operating temperature very quickly. On my 2000 NSX there is an air pump that runs briefly after start up to inject O2 into the exhaust manifold. During start the fuel mix is probably set for less than 14.7 AFR and the unburnt HC then completes combustion with the injected air in the header which generates heat to fire up the cat quickly. Other cars use electric heaters right inside the converter.

 

[tdiggity]

re: getting the cats hot - you have to drive it like you stole it and let the shop know you're coming in and to get it on the rollers right away.

Are you in NorCal or SoCal? There are fb groups for each and they can recommend smog shops that are familiar with the NSX.