CA smog help
 

Been doing a lot of reading on the site regarding failed emissions and thought it would be better just to start a new thread to ask for help rather than bump an old one. Getting close to my wits end with this smog business so I'm hoping that someone may have had a similar situation and can point me in the right direction. Here is the background:

I've only had this FD for about the last 6 months. It is 100% bone stock (even the precat). It has not been driven much over the last 10 years so I did the following before I dared get it tested:

1) Compression test (~105 Front, ~75 Rear).
2) Changed oil and coolant twice.
3) Drained gas to be safe.
4) Changed fuel filter
5) Changed all silicon hoses and tested all the solenoids. Had to replace a couple.
6) Cleaned/Tested EGR, ACV. Did a quick test on the airpump.
7) Had a look inside the cat. Screen looked clear.
8) Changed wires and plugs.
9) Full tank of 91 gas

Took it for the smog test after a good 30 minute drive on the highway and crossed my fingers. here were the results:

https://cimg3.ibsrv.net/gimg/www.rx7...1aef6677f5.jpg

Not too bad right?

So I figured I needed to make a couple small adjustments to take it over the finish line so I did the following.

1) Changed the O2 sensor. This made a huge difference on how the car ran. Much smoother. 3K hesitation was much improved but not fixed :(
2) Found out I had high oil consumption. Lots of oil in the intake so I switched the turbo assembly with a know good system. So far oil consumption seems normal now. This could have affected HC.
3) Ran seafoam through the system to hopefully clean the injectors a bit.
4) Changed the plugs again. Old ones with 200 miles on them were black. Slightly worse on the rear rotor. I think this was from oil but could be running way too rich from the compression....
5) Ran the tank down and put about a 1/3 of 91 in and added another can of seafoam (was told this could help with HC).

Went to retest and got even worse results:

https://cimg6.ibsrv.net/gimg/www.rx7...e74f9aef5f.jpg

Now the exhaust does stink like rotten eggs a bit. If my memory serves my old FD was the same except it passed with no issues. I'm leaning towards changing the cat with the Bonez high flow and try again, however the NOX is ok so I'm not sure. . .

What I am worried about that it would be impossible to pass smog with low compression on the rear. For now I do not want to rebuild the engine as it runs fine. No starting issues at all and never comes close to stalling. Quite frankly if I had not done a compression test I would have not known it was that low. The only thing noticeable would be the idle sometimes dips but then recovers really quick.

My plan was just get it to pass now and then over the next year or so rebuild the engine. So I'm looking for some input whether this is a lost cause and just do the rebuild now. It just seems like such an extreme action just to pass the test. I was hoping to enjoy the FD for a while before taking it down for the rebuild.

Thanks for reading this far!

A good stock cat is what you need for smog. The Bonez might make it worse.
I'd try again without seafoam.
I don't think the compression will make that much of a difference

For what it's worth, I trust Ari (rx7store.com) and he claims the Bonez has a better loadout and runs CLEANER than stock.

At any rate I will be finding out soon as I'm up for smog, too... :eek:

OP, please do post back when you find your issue and get it smogged.

I am going to assume by the pictures you posted that this is a test on the rollers. We don’t have rollers like that here in Maryland any longer so it’s been some years since I had to deal with that. Chances are it’s nothing you’re doing wrong. A lot of times it’s the person administering the test rolling into boost causing it to jump up like that. Have you verified the air pump is working and factory ecm? I would run the tank down put a couple gallons of the highest grade fuel available with some octane booster and loosen the clamps on the y pipe so you’ll have zero boost when they drive it.


~ GW

That test is steady state, not an IM240 test where it measures acceleration.

This really looks like an air pump/ACV issue to me. You already changed the o2 sensor. You're consistently low on NOX (low relative to "average" of passing vehicles, per the chart) and high on HC and CO. That means there's not enough oxidation reactions, which is likely not enough fresh air being pumped into the exhaust ports or the cat.

ive seen worse pass, there is something else going on besides the engine. it might be worth checking for codes, i wonder about the coolant temp sensor, but i have to say i would have suggested the O2 sensor...

does it have a CARB EO on it? if it doesn't its not legal here

Of course I could be wrong, but I'm guessing you're to the left of the window in the chart below, based on what your test results indicate. The root causes of that are typically O2 Sensor, and air pump, assuming there isn't some other major mechanical issue with the vehicle. Your car is stock and should have CEL illuminate if there are some dead sensors (unplugged etc). However OBD 1 is not very smart, and it mostly only knows whether stuff is unplugged, rather than if the sensors are "working" but inaccurate.


https://www.researchgate.net/profile...n-emission.png

agreed, it can be there for a bunch of reasons, but if the air pump is good that is usually enough if the O2 is good.
my miata has high NOX's and after a really long time i found that it was the PCV valve...

I noticed the 15 mph and 25 mph on the left side.

I agree it’s likely not enough air getting to the exhaust ports. The acv round screen that’s sandwiched under the acv itself I’ve seen clogged with junk not allowing air to get by. The ecu wouldn’t know any better. It’s pain to get at tho.

~ GW

good point on the ACV. I'm in the process of fixing mine and that round screen is absolutely covered in carbon.

Thanks for all the input. When I changed the vacuum lines I did clean up the ACV. I can't actually remember if I tested it at the same time. Looking at the FSM I can do more thorough testing on the airpump as well to ensure it is pumping enough air.

I'll remove the UIM and take another look. Once this is resolved I will definitely post the solution so we have a record of it on the site.

That's good to know. I was really beginning to think I would have no choice but to build the engine now. At least now I can focus on the air injection. Hopefully something will turn up there, otherwise I think that only leaves me with the cat. For CA there is only a magnaflow cat that is CARB legal. Only issue is that it would have to be welded in...

the stock cat is basically bulletproof, and the air injection makes it so the cat is less important than it would be on most cars.

I was wondering what happened to that car...can't believe it got away

For the smog, double check the AC fuse in the engine bay and check the voltage at the connector

Quick update

I checked the air pump wiring and operation and found it was working fine. All checks in the FSM passed and it pumping out plenty of air.

Next on to the ACV. Found the air relief valve was completely carboned up and not moving. The switching valve was moving but had a lot of carbon as well. Disassembled both and cleaned. I thought I had checked this before when I did the vacuum lines but I guess I skipped the ACV...

Car is running much smoothly and the spotty idle I mentioned before seems to have been cleared (Will confirm after a few more drives). The smell of the exhaust is much better as I don't detect the rotten egg smell anymore. Not sure when I will have time to get it smogged but when I do I will post the results here. Thanks for all your help in pointing me in the right direction. This community is the best!

Merry Christmas !!

Great to hear! Please post the emission results. I bet HC and CO are way down.

The results are in and it passed! Here are the numbers:

https://cimg3.ibsrv.net/gimg/www.rx7...f9e05b6957.jpg

So cleaning the ACV was critical to get it to pass the test. Also no seafoam in the gas...

Just to summarize for future searches. Low compression cars can pass emissions in California. In my case the rear rotor was a bit low and front rotor was fine (~75/~105). As long as all the emissions equipment is in place/working and the car fully tuned up you should be fine. The only part I could not really test was the cat. Just did a visual inside to make sure the screen is clear. The combination of a tired cat and lower compression might make it impossible to pass.

Another point to consider. The tech did mention that some of these Bosch replacement O2 sensors might not work very well compared to OEM. Not sure if there is any truth to that but my CO2 numbers are much higher than my previous FD.

Nice job!! I’m sure you feel relieved. My stock FD didn’t pass CA emission last year, either. Luckily for me, it was just a bad O2 sensor.

The fact that your 15 and 25mph CO concentration is higher than average, and your NOX is lower than average (again, average of passing vehicles), tells me that it's still running a bit rich. That could be caused by the O2 sensor. It's also possible the cat is losing a bit of efficiency. You passed though, and could probably pass for a few more years hopefully with the existing equipment.

i've seen this as well. the Bosch stuff just doesn't do very well on these cars. next time :)

Glad to hear it. The discussion on FB was rather gloomy.

It's a huge relief that it passed. Since I don't drive it much I should be good in 2 years as well. I am also getting organized to build the engine so that should put any emissions issues to bed. On FB I was looking for where to bring it for testing as opposed to technical advice and ended up being a bit of both. The technical expertise on this forum is incredible. I don't think there is a single issue with our cars that can't be hashed out here.

The shop I've been going to for the last 5 years does not like rotaries and even went so far to tell me to sell it and move on as it would never pass. He also said the same thing 2 years ago with my previous FD with 39K miles and was shocked when it passed with flying colors... So I switched shops as the tech was more positive on getting it to pass as opposed to being negative from the start.

you might take the car on a long drive, where it can run nicely and be up to temp for a while and compression test it. its weird but how well the car runs can effect the compression test.

Well FB is FB, you know how it is. FB Groups have become a lot more popular than old school forums like this, but the format of an FB group is not conducive to technical discussion. It's designed for the user experience and discussion to meet FB's business objectives, as we all know. We don't have to have a discussion about it, but I'm not surprised you had that experience.

In our case here on this forum, you have a group of owners with a lot of accumulated experience who have learned a lot of stuff by trying different things. And specifically here with passing emissions, I am literally an OEM emissions engineer who does tailpipe emission testing and development for a living. I've also written detailed articles on this forum about how the FD emission control and turbo control systems work. So I know what the results mean in the specific context of an FD, and have been able to help multiple users pass emissions by looking at the actual technical details of the test results.

You'll find similar examples where life and career experiences have enhanced the contributions of forum members. Maybe someone has a background in fabrication, or sourcing parts, or worked for Mazda at one point, or whatever else. You gotta stick together to keep the community strong.

Worth noting for future reference that the ACV check valve is still available new (PN# 1480-13-730, about $18). I replaced mine rather than cleaning the existing one (which might be overkill but I wanted to be sure).

ive lived in CA my whole life, and i've had to smog every car i've owned, plus others, at one point it was 8 cars a year.
Top Tip: go to the same smog guy for everything.

the car most clean; was either the Rx8 or a 1980 MGB tuned a bit lean,
runner up was the 99 FD that thing was squeaky clean...

funniest was the Lancia Scorpion, it was like a comedy. first try it failed badly. so i put the cat from the FC in it (its the same size), and it blew up the coolant overflow bottle on the dyno. try three melted the rear bumper (Rx7 cat works hard) and then try four it actually passed.....

I'm definitely going to stick with the same guy with my other cars as well. I don't think he will forget me and he really took his time to make sure I had the best chance at passing. He even set up a huge fan in front to provide some airflow which is something I had not seen before for smog.

My RX8 is also super clean. Probably will stay that way until the cat gets tired...

i like to go old timey, and have a good cat for Smog days and then run some beater the rest of the time. the Rx8 cats go bad and they are not cheap, in fact cats are so expensive that the OE Mazda part is probably the cheapest and its $1000

This. Have a spare ~5K mile OEM cat for smog check sitting, just in case my "daily driver" cat gives out one day.

Will having pre-mix in the gas affect emissions? Just wondering if I need to drain my gas prior to testing.

Yes it will affect the test. Make sure there are no additives in the tank to give yourself the best chance of passing. I would not drain the tank but just run it down and fill it up with premium.

My 1980 SA just failed. When I resurrected it (inherited from a deceased relative) a few years ago to get it licensed in CA, it passed just fine. Now, a few thousand miles later, not so much. I was adding some pre-mix, but ran the tank down and filled with premium before the test (with no pre-mix), no luck. Took it to my mechanic (the guys that resurrected it in the first place), they leaned it a bit, still no luck.

Any pointers of the above situation? Anybody know if / when CA will decide a 1980 vehicle no longer needs to get smogged?

Thanks.


https://cimg8.ibsrv.net/gimg/www.rx7...fe6012837a.jpg

Sorry, should have added this to the 1st Gen Forum. But the search for "CA Smog" came up here in 3rd Gen.

In any case, I'd suggest your cat is not fully doing its job. Did you make sure to get it very warm before the test by driving at highway speeds for 20 miles or so?

Yes, ran it for a good long time before the test. The mechanic that took it in for the re-test did the same. I'd say you're right, though, about the cat. They checked readings before the cat and after, essentially the same.

CO is often tied to the combustion/ignition timing. At the most basic level, check the plugs, wires and base timing.
Correction -that was meant for the original post...

a 1980 car has a Thermal Reactor, no cat

write your representative and tell them the program has been a success and they can just make it go away, please. i did and i heard back from the assembly-person before i heard back from the BAR (Bureau of Automotive Repair, which was a pretty useless phone call, they are responsible for the smog licenses and the software, and YOU are responsible for everything else)
they had a list of 3 bills that were dead, and a 4th that was probably going to be. the smog program isn't popular, so if they can get rid of it without looking like they are soft on the environment they probably don't care much.
if you don't know (i didn't) the CA govt uses an Assemblyman, which can be a woman, and a State Senator. took longer to find out who these people were than to write the email.

Hi all, new owner of 93 touring. Maybe I should start a new thread, but I figured this is kind of related. Has anyone had any luck passing CA smog with any mods? For example, stock ECU/tune, stock turbos, stock fuel system, but upgrades on both intake side and exhaust side? I was hoping to do some light upgrades and tune with PFC, but swap to stock ECU for smog.

@nmoffatt thanks for documenting your smog tips!

This has been covered quite a bit. California is a tricky state, the big thing here is that you can fail with a visual inspection in some instances - open air filters, big exhaust, etc.

For passing the sniffer test, working air pump, good stock main cat, stock ECU, good fresh plugs, good gas - that all helps a great deal.

Dale

I'd say you need to check your air pump operation.

CO and HC are high (above average according to the report), and NOx is below average. That shows you're not having enough oxidation reactions, and the air is likely not lean enough.

@DaleClark thanks I will do more searching on the subject. I’m a little bit more optimistic that passing with a few mods is not impossible :). Btw, I’ve been a lurker since 2004 and I remember reading up on your advice back then. Fast forward 18yrs, I finally have an FD and am looking forward to working with the helpful and knowledgable community on here! Lucky to have cool dudes like you.

@arghx sorry for the confusion. I hijacked OP’s thread a little. The test results are from OP, but looks like cleaning the ACV is what did it.

Dale is right, the visual gets tricky. the aggravating part is that you can follow the rules (HKS and Greddy had CARB legal stuff), but the smog guy may or may not follow them. the smog guys are, or seem to be under a lot of pressure, apparently the state has the money and time to send fake cars around or even rent the place across the street and shoot video (which is really crazy because 2/3's of the state doesn't smog cars at all). actually around here they don't really want to even smog cars older than 95 anymore, its "too much work". i would suggest finding someone and bringing the car to them, if they know you and recognize it, it helps.

anyways two stories. last time i smogged my car, which is an REW swapped FC, it passed with the Re Amemyia ecu, and the down pipe. i didn't even warm it up, he spent enough time doing the inspections that i guess it was fine.

the second one was my friends car, it had a down pipe, and a 99 spec engine, and 99 ecu. i took it to guy #1, he did the entire test, which it passed, and then says "i dont like the down pipe i can't do it" i should point out that his is fair, it should have the precat, its just frustrating because it had passed the test
shop #2, after a while there is a guy looking at something, and then two, and then 3, and after 45 minutes i walk up and ask if i can help. they say they are looking for the EGR valve, i tell them it has a code for that. they say they don't care they need to test it. i ask if they are going to tear apart the intake for 2 hours to test the valve. they say they can't do it. they ask for the full fee...
guy number 3 just did the test and the car passed for the third time

please write your representatives and tell them this program is not needed anymore :)

Yes, the CA BAR is really cracking down on shops that clean pipe or otherwise falsify the inspection. The RX7 is a high tampering vehicle, so if you live in a part of the state that requires testing you generally have to use a test only station. I have been going to the same shop for the last 3 renewals, and I bring last year's inspection report to "help" them and it does seem to give them more assurance about the car. My FD has a JDM Mazda downpipe, it is pretty old looking and with the heat shielding it looks like it belongs there. They always spend much time looking the car over from top to bottom for any illegal mods despite my history with the shop, fortunately they have not flagged the DP.

@j9fd3s and @jza80 thank you for the info. Good to know it is possible to pass with stock ECU and down pipe (assuming visual passes). Did you have any mods on intake side?

I passed with a 'cheap bastard' intake which is a modified stock airbox, a downpipe, SMIC, PFC, and Racing Beat twin tip exhaust. I even have BNR stage 3 turbos. As long as it passes the sniffer test, just make it LOOK as stock as possible and get the hell out of that smog shop if the tech guy seems like he isn't in love with the FD. I've had more than one shop "work" with me on visuals because they flat-out liked the car. :)

my car has an HKS intake (which is CARB Legal) and intercooler, so yes. i've had all kinds of crazy crap pass.
the must haves are the Air Pump and a functional ACV. the FD also wants a good O2 sensor. the factory cat also is the best one, hands down, its also the most robust part of the car too.

since new cats are basically impossible to legally get in CA, we're starting to save the good cat just for smog tests, the Sunday cat, and then we have one for the rest of the time

I have a stock airbox fed by a 99-spec air inlet. But it looks completely stock. A "cheap bastard"-style airbox is also fine if you want more airflow, the cut out bottom section can't be seen in a visual. I had one of these on my car during my smog inspection ~2 years ago, however I have since removed it. When I first installed it, I found that the air pump honking noise was way to loud, so the solution was to insert a muffler plug in the air pump outlet hose. That removed the majority of the noise, but also seemed to create backpressure that messed up the ACV system and I saw considerably increased NOx levels from the test. For this latest test about a month ago, I had the OEM uncut airbox installed and the muffler plug removed and NOx was back down to normal with no other changes to the car. I think that when I had the muffler plug installed, some surplus output from the air pump was passing ahead of the cat or otherwise entering one of the air injection pathways at inappropriate times and creating some NOx. That air pump puts out a tremendous volume of air. Having the muffler plug installed, which resolved the majority of honking noise, also severely restricted the bypass air that normally feeds into the airbox. It had to go somewhere, I guess. YMMV..

Anyway, I think intake mods will not change the test result one way or the other, as long as you can pass visual. There isn't enough airflow from the ASM test mode to make a difference. A good condition stock cat is a must, though.

Just following up on this as it was time again for a smog check. Now that the FD is being driven more regularly it passed very easily. Since the last smog check the following has changed:

1) Added HKS Twin Power
2) Added SS Downpipe.
3) Had the injectors cleaned at RC.

I went for a 1 hour drive before the test after filling up with 91 at Chevron. Also changed the oil the day before.

Here are the results. Hopefully this could help someone down the road.

https://cimg8.ibsrv.net/gimg/www.rx7...dbc5e52ac3.png

I'm assuming that means you went from stock pre catted downpipe to aftermarket stainless steel open pipe. The reason that doesn't affect your emission test result is because the test isn't meant to capture a cold start. If Mazda could have passed the EPA testing (which cold starts in a lab at 75 degrees F) without an expensive pre cat they would have. So as much as we complain about regions with stricter emissions requirements, it's still not nearly as strict was what the car had to pass when new.