My car has passed smog every time since new but now I am worried about the next check soon. After having all my coils fail, I have repeatedly driven several miles at a time with no spark in one cylinder and gas going straight through the cats. This has produced the characteristic rotten egg smell when it has occurred.

Everything is fixed now and have no CEL, no rattly loose stuff in exhaust, and I can see on my temp gun that the outlet of each cat is much hotter than the inlet, so it is working somewhat at least. Also, I just replaced the downstream O2 and it was not melted or anything so all looks fine that I can see.



Basically I'm asking if you think it's worth it to pay less for the cheaper smog test that does not actually certify the car for the state, but checks if it is likely to pass the real test. Or just go for the real deal now?

Also, in the case of it needing work, I have read that the big downstream cat does most of the work when the car is hot and so I may be able to pass by just replacing that? Does this sound right?


This is a CA-spec car in California.

 

It all depends on how your local veip emissions branch wants to handle the problem. Here if you go for the real thing pay up front for the amount cost is for the test than, hope it passes on the first try, if not it fails they will give you the results and send you in their office where your forced to make the next appointment and a print out sheet with error code and come back on that date to get it done. The print out has a window of time to get the problem fixed than try the test again without paying, if you passed its done with. Find out how it works in your local area than get back to us. If you have a place where someone can hook you up go for it. Good luck on whatever you decide to choose.

 

I used to live in Cali and had a car that failed the emissions test. I was given a 30 day extension on the deadline to get the car fixed and then take it to a California operated testing station where it would be checked for free.

I would just go and get the regular test done. I think the cat is still OK, you really didn't drive it that much.

The main cat that you call the big downstream cat is the one that does the work. If the car were to fail the test, this is the one to replace. The 2 precats in the y-pipe are to control the emissions on a cold start until the main cat heats up and can do its job. The main cat only needs a minute to warm up.

 

Since I live in Cali, I have dealt with this problem before with older cars. This state is a PITA when it comes to emissions. Your cats are probably okay. What I would do is add some TCW-3 outboard motor oil to your gas. It was designed to reduce emissions. I run it in my car before and during emissions tests. Many members here use it and it does work. Use 1 ounce to every 5 gallons of gas. Be sure to use premium gas for your test. I know the anxiety you are going through. These tests suck because not all the test equipment is uniform. I always test early in the morning before other vehicles contaminate the test equipment. I always pass with low emissions.

 

Thanks so much guys, I'm going to give it a try with the outboard oil added and let you know what happens.

 

As an update, I ran a few tanks of premium through it with that oil and it easily passed. Especially the NOx was extremely low, like 0.4 with a max of 700 or something like that.

 

Congratulations!!!!!! Thank you for the update. I just smogged my 98 I30 with TCW-3 in the gas. Out of 717ppm allowed it recorded 4. Every time you get your emissions test, use the TCW-3 and you will easily pass. You should run it in your gas regularly anyway. I have been putting it in my gas every fill up for the last 7 years.