Just Failed CA Smog. Now what?
 

I bought my Z just over a year ago. Presumably it would have had to pass smog at that time. This time, everything passed except for NOX. Max for the 15MPH test is 545 PPM. My Z measured 587 PPM. The 25MPH test passed with 459 PPM. The Max is 502 PPM. The car is stock except for a KnN filter. I just went through some of the CA smog related threads and there seem to be folks who got a measurement in the 200s. In this thread by Z51JEFF, it looks like he passed by replacing his O2 sensors. Is this what I should try? If so, does anyone know what model and where I can get them and how many? Is there any way to tell after replacing the sensors whether it will work short of taking another smog test? Thanks!

Re: Just Failed CA Smog. Now what?
 

Did you have the power key in the FULL position during the test? If so, you may want to switch to NORMAL and run the test again. Ask me how I know.

Re: Just Failed CA Smog. Now what?
 

Nope. I had the key in my pocket.

Re: Just Failed CA Smog. Now what?
 

Nuts! Too bad it couldn't be something so simple. Good luck.

Re: Just Failed CA Smog. Now what?
 

Do you have the stock prom? Jerry's sells the O2's. Will the testers in Calf. let you run the test in a test mode to see if it will pass after you change the O2's?

Re: Just Failed CA Smog. Now what?
 

additional ignition timing would elevate NOx, but usually the port throttle closed timing map at the lower rev ranges doesn't deviate from stock much on some tunes.

If the other numbers were looking good except for NOx you surely need new O2 sensors. Cleaned my car right up. I will need to see your exact results for a more specific diagnosis though. Another easy fix is if you have a bad vacuum leak under the plenum somewhere (you can tell by a high idle).

I got the oxygen sensors from O'Reillys- they have the proper length 3 conductor wire harnesses.

Re: Just Failed CA Smog. Now what?
 

Was the car hot when tested? have you given it a good run @ wot beforehand and clean oil? My SS failed ever so slightly.. I gave it balls to the wall for 15 mins and came back and it passed with flying colors.

Re: Just Failed CA Smog. Now what?
 

First time I tried to pass smog. Failed 3 times. Changed Eprom/Chip. Passed.

Last year I failed too many times. lol

Changed out the O2's. Picked up a pair of Bosch at the local parts store. Failed
Had to change out a bad injector it had 8.8 ohm's. Failed.
Then shop noticed the key in full power. They switched the key and passed. For got about the key after I changed out the injectors.

15-518 25-452

My shop suggested to change out the cats.

Re: Just Failed CA Smog. Now what?
 

AFAIK, it's the stock prom. I haven't touched it at least. I doubt the tester will do a test pass. I do get a second official attempt for free within 30 days though.

Re: Just Failed CA Smog. Now what?
 

Yes. All of the other numbers looked good. Here's the report:

http://i34.photobucket.com/albums/d1...pschga0cwq.jpg


Now that you mention it, I haven't heard that clicking sound indicative of a vacuum leak when I start the engine in a long time. How high is considered a high idle?

I looked up both O'Reilly and Jerry's and found the following sensors:

1) O'Reilly: Bosch - Oxygen Sensor - Part#13077 ($45.99)
2) O'Reilly: Bosch - Universal Oxygen Sensor - Part#15726 ($57.99)
3) Jerry's: Delphi - Oxygen Sensor - OEM? GM PN 10137641 ($47.75)
4) Jerry's: Denso - Oxygen Sensor - GM PN 10137641 ($59.75)

Would all these work? Which is the preferred part?

Is this something I can easily swap out or should I take it to my mechanic?

Re: Just Failed CA Smog. Now what?
 

It was about a 10 minute drive from work to the smog check station. Half local half freeway. I had the power key out. It's been around 2500 miles since my last oil change.

Re: Just Failed CA Smog. Now what?
 

Is there a limit to how many times CA allows you to fail or can you try as many times as you need? My registration renewal deadline is 3/8/2015. Does that mean I need to pass before this date?

Re: Just Failed CA Smog. Now what?
 

Pay the registration before 3-8-15.
Dont want to get dinged on the late reg. Cal DMV wants there money....
My reg was up in Feb 2014 passed in Jul 2014

Re: Just Failed CA Smog. Now what?
 

No limit.... I think mine failed 4 or 5 times before it passed.

https://scontent-a.xx.fbcdn.net/hpho...03&oe=554923EE

https://scontent-b.xx.fbcdn.net/hpho...40&oe=55542239

Re: Just Failed CA Smog. Now what?
 

The O2 sensors.

the drive side is easy.
This is what I used to get the passenger side one off.
https://fbcdn-sphotos-f-a.akamaihd.n...86ae497676f3a9

Re: Just Failed CA Smog. Now what?
 

The hotter the combustion temps are the better it will be on emissions. flip that power key and nail it a few times to heat it up and clean it out. Drive it around for 15-20 minutes with a few wot and take it hot to the test. I know you probably don't want to chance it on that but if they'll retest for free im fairly certain it would be enough to pass was for me. Oh and also the catalytic converters work better when hotter too so that may be all it needs.

Re: Just Failed CA Smog. Now what?
 

I found a couple of threads here and here about replacing the passenger side sensor.

Ummm...here comes a dumb question...where are the sensors located? Would I be able to find a diagram in the FSM?

Re: Just Failed CA Smog. Now what?
 

Before the cats on my 90

Drivers side.
https://fbcdn-sphotos-c-a.akamaihd.n...53a3629892c296
Passenger Side (From the bottom) best pic I have....
https://fbcdn-sphotos-e-a.akamaihd.n...8753fd83bc399d

Re: Just Failed CA Smog. Now what?
 

I have the $45 Bosch ones from the parts store. They have been thru two smog test cycles now and pass. The originals were German made (also Bosch), but these are of US manufacture. One of the ones i got from Jerry a couple of years back had awfully short leads...I don't know if he is selling a different one now.

the o2's might clean up the low speed hydrocarbons a little too. They don't last forever. For NOx they have to be dead accurate as the sensitivity to lean or rich conditions elevate that gas quite rapidly. I'm sure you'll do better after you swap them for new.

Re: Just Failed CA Smog. Now what?
 

The cats need to be hot and the coolant up to temp (so it doesn't run rich), but hotter combustion, extra ign timing, lugging in gears at low rpm etc will spike the oxides of nitrogens thru the roof. If anything, run with a chip made to be all stock except for the part where it turns the cooling fans on at 205 degrees (instead of the factory 228 deg F). high combustion temps bad, high catalyst temps good.

Basically pinging is the ultimate NOx production condition. egr normally blows a puff of dirty air right when you crack the throttle to keep combustion temp below the threshold for nox. but of course the early cars have 11:1 compression and no egr.

Re: Just Failed CA Smog. Now what?
 

I agree with Z51Jeff and Mike100. I had the NOX issue too. Everthing passed except for that on the IM240 test. I found out that I had a lazy O2 sensor on the left side by using my Mastertech 3100 to watch the voltage swing. Replaced the O2's and passed. The new results were about 40% lower. I used the Bosch ones.

Re: Just Failed CA Smog. Now what?
 

I just saw this thread. I feel for you, OkDok!
I had the same problem passing CA smog with my Z.
All the recs already given are GREAT ideas.
I did them all (and some others!) to jump through
the hoops to finally get it to legitimately pass the sniffer.
Let me know if you want to talk privately....

PS: Some of the steps you do, like new O2 sensors, oil change
you can think of as general maintenance for an (old) car anyway.
What's a better word than "old"?

Re: Just Failed CA Smog. Now what?
 

Move to Texas :-)

Re: Just Failed CA Smog. Now what?
 

What's really frustrating is that the pass levels are much tougher now
than when the car was originally designed and built. So how are we
supposed to clean them up? In their minds, this is how they get rid of
the "smog machines".

I agree that the air is MUCH better now than in the 70's, so there has
to be a comprimise. As others have said, if a stock Z is running (really)
well, it should pass, maybe with a few changes/tricks.
With mods is a different story.

Re: Just Failed CA Smog. Now what?
 

I have not had my "Welcome to California" smog testing yet. I guess I am too scared to find out. Actually have not had any time to attempt registering the car in this great State. I'm considering buying a nice, stock, low mileage ZR-1 and getting rid of mine...we'll see. Thanks for sharing all the tips and tricks and I will see if I can pass one day.

Best wishes to the OP.

Re: Just Failed CA Smog. Now what?
 

After you fail a few times you will be instructed to take the car to a referee station. This is a State owned facility,this place will make a decision as to weather the car will not pass,pass the car with an exemption or not sure after that,I couldn't get a straight answer out the guy when I there a few years ago. I got a little help from our friend in Ill when it comes to passing the test. Is it legal,I could care less. Ca has dropped the max limits on the Nox levels from 702 in 2008 down to 502 in 2014. Replacing the O2 sensors in not an easy job,at least getting one of the plugs in. I had o jump through hoops to get a bone stock 91 to pass with 20,000 original miles. What really suck,my car at 6000 original miles wouldn't pass today. I can help with the smog issue if needed.

Re: Just Failed CA Smog. Now what?
 

Geeez, maybe I should look at the 68 Convertible instead if I plan to live in Cali for a long time? I'm starting to think my car with the Stage I cams will never pass. Thanks for sharing. Now I see why the locals say the "SMOG Nazis"!

Re: Just Failed CA Smog. Now what?
 

Locals.. heck I call the Cali Smog people that here in Chicago... Meanign they are well known as Smog Nazis outside of the Peoples Republic of Kalifornia

Re: Just Failed CA Smog. Now what?
 

What happens in CA won't necessarily stay in CA. The above examples of lowered NOx levels on our emissions tests come from what I believe were EPA limits that kicked in during 2012 or so from some law passed back in the 90's setting tiers to be met at certain future dates. We just happen to follow that trend (or actually set them in many cases that the EPA adopts later). What worries me is if they can/will lower them any lower knowing full well our older cars were designed to meet limits of the day, not modern ones.

As it sits now...big deal, you can definitely pass the testing- it is just that oxygen sensors don't work that well when they are 20 years old- you gotta get new ones. The problem is not clean tailpipes, but the rigid visual in this state.

Re: Just Failed CA Smog. Now what?
 

I understand what you mean. The only other SMOG state I lived in was Connecticut about 15 years ago. Back then it seemed I just tested because I had too and routine, but had an issue passing. The car would have to be a POS and was running very poorly it seemed.

Re: Just Failed CA Smog. Now what?
 

I can see that I will have to try to get you to help me to pass when the time comes. I have not even looked into all the stuff I have to replace to pass visual since no C.A.R.B. approved stuff. I did buy a stock air cleaner so far and exhaust manifolds/cats from a 95 take off with 2K miles.

Re: Just Failed CA Smog. Now what?
 

Off topic:

Hawaii, when did you relocate to Cali? I must have missed that

Re: Just Failed CA Smog. Now what?
 

I had to suddenly relocate to Cali last May after I returned to Hawaii from Japan in March. Long story, but basically for a job offer after my position in Hawaii being obligated to someone else returning from overseas. Thanks for your thoughts.:cheers:

Re: Just Failed CA Smog. Now what?
 

The one saving grace you have is that your car is not yet assigned to any particular zip code and bringing it in-state for the first time will get your target limits assigned to unenhanced area levels (higher limits). The next time will be the enhanced urban area test at the tighter limits though.

Re: Just Failed CA Smog. Now what?
 

I can help when the time comes.

Re: Just Failed CA Smog. Now what?
 

Thanks for the info and I have to dive into this more. I know they are going to penalize me for not changing title and all over knowing I brought it in last summer. They want their money (use tax) even if it is sitting in my garage with Hawaii storage title. I thought I might sell it so did not want to bother until I make a decision. Thanks again!:cheers:

Re: Just Failed CA Smog. Now what?
 

Thanks for the offer and greatly appreciated. I have a few issues to address when I have some time before I can even think about trying to SMOG it. I wish there was a way to get a test to just see where I am at without them putting the car in the system.

Re: Just Failed CA Smog. Now what?
 

I see on reason why you can't do a pre test. Getting the car to the testing facility is the problem. Use a trailer or get a temp pass from the DMV.

Re: Just Failed CA Smog. Now what?
 

Ok. I'll bite.

How does some one from Mesa AZ know you can "pass" the CA Smog Check only with the secondaries disabled.

Re: Just Failed CA Smog. Now what?
 

"tf95ZR1" gets a "Beacon of Reality" Award.

The reason the max. limits for the Smog Check have been getting incrementally higher is that the State of California wants to drive old cars it believes are "high-polluters" off the road and the 2G ZR-1s are considered "high-polluters". Because there are so few of them, the politicians have nothing to loose by forcing them off the road or out of the State. Sadly, this NOx problem is really tough for 90-92s which lack the EGR valve.

Here are some tips:

Fresh fuel
Clean combustion chambers and piston tops
Stock spark schedule
Proper O2 sensors. I use Densos. I think they are better than Bosch or Delphi. PN 2343005 $28.79 from Rockauto.com
Cats really f'ing hot.
ECT as low as it can get after getting the cats really not

For those with '93-'95 who flunk NOx...buy a revised cal from Marc Haibeck which turns the EGR on at 14-mph rather than 17-mph.