CA smog: what causes my bad smog report?
 

Here's my actual smog report. This car has always passed easily and I put in a Bonerz cat about 5 years ago. But last year I replaced the intake manifold orings, or rather, my inept mechanic did. Since then it will only hold an idle when warm, and at 400rpm, so I have to do something.

It failed a "test only" smog test.

I'd rather have someone else do it.

I appreciate any light anyone can shed on this.

I want to sell this car, but vehicle prices have gone thru the floor around here because of gas prices and general economic misery.

Is your car running really lean? I think this because of your low NO numbers. Could this lead to high CO and HC numbers and also high CO2 levels? It is a good thing there is not any O2 because your catalytic converter is working.

I am not too sure but it could be possible that the engine should be rebuilt to be running clean and the car able to sell. Good luck

0% o2? that's pretty extreme.

Low o2, low NO, very high HC, high CO2... to me, that says extreme rich mix, or an air-control valve problem.

You're consuming absolutely all available oxy, and still not burning the HC's.

rich
 

NOX is usually high if it is running lean and low if rich. Your HC is high indicating a rich mixture OR misfire. Is this on a carbureted 12A or on a fuel injected 13B SE?
A full tuneup and a shot of seafoam would be a good start.

This is a stock 12A with nikki carb, low mileage, and never has been a problem. But it's been sitting around unused (except for weekly airing out), but it's been idling low ever since I replaced the manifold gasket and orings.

Seems to run good above idle.

your problem is probably related to the low idle. since it happened AFTER the intake gasket change, that would be the first place to look.

I hope it can be solved by adjusting the idle and mixture screws. I have the instructions from Sterling, I have the loooonnngg shaft screwdriver, now I have to remove the air cleaner (the whole canister, I think) to get at the screws and I have to cut off the factory cap (Dreml?) over the mixture screw. Then walk it thru the adjustments.

Has anyone ever tried "Smogtips"? they have a scheme where you crank the numbers, etc., into their form, along with any other info, and for $20 they diagnose it. After carefully transcribing the data into their form for about a half hour I paid the $20 and now I await their diagnosis in my email.

I'll check that before I pop the air cleaner off.

"Smogtips" provides the service *free* if you use one of their test stations, so I'm going to test ANOTHER car this afternoon at a Smogtips station (I got a $49 full price coupon).

Then, after all that, I have to "Test only" my 83, too, but that's usually a breeze (just one of the reasons it's my favorite alltime car).

I had success prying off the factory cap with opposing screwdrivers. Perhaps a dremel will work, but space is limited.

I just rocked mine up and down until the tang snapped, years ago.

(The Cali air mix screw smog caps are different from the rest - - they are a metal can that prevents you from reaching the screw with anything except a very special "security" screwdriver. They're atttached to the carb by a screw through a metal tang at the bottom. You can only pull the screw by removing the carb, but it's not that hard to bust the cap off.)

I'll try rocking the cap , after I remove the air cleaner : the whole thing, to get access to the two screws.

Meanwhile, I gotta lean out my 83 which flunked with high HC because it's running too rich. I leaned it down 4 half turns today to where it barely started hunting, and then backed it out 1/4 turn.

My 83 failed too, just barely.

I can see the mixture screw on the 83, so, since the idle was good, I started the tuning process with the mixture screw by turning it in (CW) until it started to hunt, then backed off 1/4 turn. The screw went in 2 whole turns before it started to hunt, and since the cap was missing I conclude that a previous smog checker had adjusted it and left it too rich and that's why I failed last week.

I'm going to put in fresh plugs and check timing then take it back to the "Test Only" station and get my free re-test. I figure it will pass this time. If not, I'll have to do more.

Too bad I don't have someway to test before going in.

I can see that the 85 has the screws buried under more stuff than the 83 has. But even on the 83 it's almost impossible to reach the idle speed screw without removing the air cleaner assembly. Fortunately, I don't think I have to.

Here's the 83 smog test result:

I've been searching, with no success so far, for a rental place that will rent an exhaust gas analyzer.

Portable ones exist, and I'm amazed that rental places don't have them.

It's probably because the new smog tests require a dynomometer for the actual pass/fail test.

Anyway, I still have to figure out what to do about the Fuel Evaporative Test, i.e., the charcoal canister that recycles gas back to the tank. I think that what's indicated is a leak in the return hose.

if you are pretty close to passing smog, you can try adding a little denatured alcohol introducing more oxygen into the mix and making your engine burn hotter

Here's my plan for a free re-test:

1-new plugs
2-check timing
3-add alcohol
4-drive an hour before going in.

Nuts! The 83 failed again, with even higher HC!

I leaned it out to where it started to stumble and hunt, and then backed off (CCW) 1/2 turn. Changed plugs, added some alcohol to the tank, and the HC is even higher!

Could be a leak in the carb (except this engine never runs rough and never backfires), but why would that be worsened by leaning the idle mixture?

I'm at a loss to explain it, or know what to try next on the 83.

Haven't touched the 85 until I get the 83 clear.

Rats! I was hoping some alcohol will do the trick. Hope you haven't lost too much faith.

I searched what would be a good ratio mix for the alcohol:gasoline mix and found a few different responses. I do not recall exactly how much I was recommended but I believe it was 1:2 alcohol:gas mix ratio.

Besides having the engine fully tuned up (plugs, oil change + filter, clean air filter, etc.) right before a smog look at the emissions equipment.

For myself I found out that my air control valve was malfunctioning. The car would run fine but I did a test (disconnect rubber recirculating pipe from ACV to bottom of air cleaner cover unit and rev engine past 2500 rpm). If more air flows out still as rpms increase, your CA ACV is not working right and there is no air flow to your catalytic converter to burn hotter and efficiently clean all the emissions. This can be a pricey fix.

Again let us know how the results go. Good luck! Hope you pass soon and get your car on the road legit!

ACV, eh? Well, I can see that possibility. A couple years ago while getting a Smog Check on the 83 the mechanic called me and recommended a new cat, so I said OK since it was 'only' $200 installed. But now I wonder if the air tube was hooked up properly and if the cat gets enough air to burn up the HCs that I'm reading high?

I have a spare ACV, but it's a Pick 'n Pull so it may be bad.

Yeah, I was hoping for your sake that it was mix, and not the ACV.

Cat's never an issue for the SA's (didn't have any, originally), but the ACV is crucial, cranky, and costly.

I wish I had more to contribute but all I can say is good luck.

I'm glad I live in an area where this isn't an issue. FBs are SO much easier to deal with when you don't have to worry about emissions control devices.

When I first read the title "CA smog: what causes my bad smog report? " my answer in my head was "Driving an FB" lol.

Jon

Maybe your cats prefer a slightly richer mixture like j9fd3s was saying. You're working to lean it out but perhaps it's producing a negative reaction.

Well, I read the California DMV website about smog stuff, and it recommended I call the Bureau of Automotive Repair, so I did. The number is 800-952-5210 and you have to push through a few voice menus, but eventually I got a *human*, who gave me some help and advise. Didn't have to wait long either.

He said that probably all I need is a carb overhaul, replace some gaskets and rotted out rubber/neoprene seals. said that sometimes the carb floats get gas or water inside and sink, resulting in too mush fuel. He was able to hustle up my failed smog charts.

So, if it's not TOO hard I'll overhaul the carb on the 83 and check the ACV and the hose-that-gets-burned while I'm in there.

Or maybe I should just put a Sterling in. Trouble is I need another core carb.

Carb o'haul kits are $46 at rockauto, $60 at NAPA, and $66 at mazdatric.

Really?

I suppose it's possible, especially since my O2 number is so low.

Too bad I don't have an easier way to check emissions that's better than spending $25 (average) at the Smog shop. I could richen it back out a turn or two.

Has anyone ever seen this?

Hey glad to hear you are working fast with your ride.

Hopefully if you do need to change your ACV, the one from Pick-n-Pull will work. There are two different kinds of ACV for the Series 2 (1981-1983). One is called "federal" and the other is for California models only. So I made sure I had the right part number for the CA model meant for CA emissions equipment installed on our CA FB. I have a thread about my smog woes and I posted some things I did to pass my car including the ACV part number and gasket part numbers, and other stuff.

Perhaps your carb does need a rebuild. I can not see what hurt it can do, but you say your car is running top notch so that may not be the case necessarily.

OH one more thing! When you put your hand (careful of the hot exhaust heat shields) or whatever to test air flow going to the cats you probably cannot feel it because the air going into the cats are very minimal just enough to make it burn a little hotter. I believe with load on the engine there will be more pressure going back to the cats. But the way I tested to see if an ACV works is by making sure the diaphragm "switches" when revved past 2500 RPM.
Good Luck! :icon_tup:

Well even if you richen the mixture up a little there should not be a problem if your cats are working fine. That's their job anyways to clean up any excess fuel/combustion bi-products. If there has not been any air supply to it since the time you replaced them, they go bad fast. Or perhaps it was a cat not meant to handle rotary engine exhaust temps and failed like mufflers not meant for rotaries do? I changed mine too but it was a Bonez unit I bought from Rotary Performance and it is suppose to handle high temperatures of a rotary exhaust and this made my car pass smog. Then also, my ACV has not been working probably since I bought the new cat system and I replaced my ACV for this year's smog check since I failed again, thus I do not know how efficient my cat is performing anymore. So if everything else still does not work for you, you may have to look into replacing your car again.

All the best!

yes. back in the old days, we played around with an 84 i had on a gas analyser.

when you set the mixture so the engine ran the best, it barely failed. leaning it out make it worse. richening it up made it pass.

if you were to put an o2 sensor right before the cat, on a stock, functioning car, you would see that the mixture is about 16:1 (it'll vary a little). this is due to the air pump supplying air into the exhaust ports. the cat works best with a mixture closer to 14.7, so running the engine a little richer than normal lowers the smog numbers.

running the engine lean creates misfires, which is like a full chamber of unburned fuel going into the exhaust. misfires will basically spike the hc's way up.

the evap test is pretty simple, they just pull the line from the charcoal cannister to the gas tank and see if it holds vacuum. it actually should, theres not many places for it to leak.

i'm in CA too, ive been smogging these things since like 1993, they all pass leagally too.

The PnP ACV I have is from a CA PnP so I'm guessing it's CA rather than federal.

Those ACVs cost about $400 from mazdatrix! I'm guessing that just the diaphragm (are there 2?) ruptures, or something. What else can go wrong with it?

I wish I could pinpoint the problem a little better. Right now the possibilities seem to be:

1-leaky carb
2-bad ACV
3-burned out cat
4-bad rubber tube under the carb

I need a way to eliminate some of those so I don't go replacing unnecessary stuff.

I put a new Bonerz in my 85 about 5 years ago, and I think they last long as well as flow well. Maybe I should do the same on the 83, just on General Principles.

Carb rebuild kits are about $50-60 but maybe I need floats, too. I suppose I have to remove the carb to rebuild it, which is a hassle. Do I have to remove it or can it be o'hauled from the top?

This is the 'smogtips' analysis I paid $20 for:


SMOGSMART VIR REPORT - 1983 MAZDA RX-7 1.1 LITER

SmogSmart VIR Report #154366



Your vehicle's emissions results: High CO at 15/25mph. High HC at 15/25mph. Possible rich fuel mixture. Vehicle failed CO with very high numbers. This condition is called a "rich fuel mixture". The diagnosis for this failure should include close inspection of your vehicle's fuel management and control systems, with heavy emphasis on the carburetor.



What causes a Rich Misfire, and how does that create high CO: CO stands for Carbon Monoxide. It is a by-product of incomplete combustion, more then often related to the presentation of too much fuel to the combustion chambers. The spark created at the sparkplug can only burn a small amount of fuel, the fuel it cannot burn is sent out the tailpipe and will normally contain high levels of partially burned fuel(CO) and un-burned fuel(HC). Let's look at two primary causes for excessive fuel presentation to the combustion chambers.



Fuel distribution in your vehicle’s engine is primarily controlled by the carburetor. If any component within the carburetor is defective air/fuel ratio can be disrupted and result in incomplete combustion. The presentation of too much fuel will produce high CO emissions. The presentation of not enough fuel will produce low CO emissions. If your engine's carburetor is defective you have two options. You can ask a local smog tech to try and adjust the carburetor (if possible) or you can ask to have the carburetor rebuilt (a little more expensive but the performance increase will definitely be noticeable).



On computer controlled engines, fuel distribution is also controlled by the vehicle's computer system (ECU). The engine has several emissions sensors such as the, TPS (Throttle Position Sensor), ECT (Engine Coolant Temperature Sensor) and the MAP or MAS (Vacuum/Pressure Sensor) which send vital engine information to the computer, and which the computer uses to determine proper air/fuel ratio.

Your vehicle's engine is NOT computer contorlled. Your vehicle does not rely on any electronics for fuel/air control... getting it to pass the smog test will be a simple matter of adjusting the carb or if need be getting it rebuilt.



Final Comment: There will be a few steps involved in finding out the root cause for your vehicle's failure/s. The emissions system/s responsible for causing high CO & HC will have to be individually diagnosed, and step-by-step eliminated as faults. Please Remember: California law only allows State Certified Smog Repair stations to conduct smog inspections and smog repairs on vehicles being driven in California. We highly recommend you search our database of SmogTips State Certified Smog Repairs stations. SmogTips Certified Stations are pre-screened for quality repairs, fast friendly service, and reasonable prices.



SMOGTIPS SMOGSMART VIR REPORTS - Save Money. Smog Smart. SmogTips.com - "California's Leading Smog Check Support Group" - 1-877-SMOG-TIPS

Aha! So maybe I should richen it a little and retest!

I can probably check that cannister hose with an airpump.

Well richening it up makes sense. I would have leaned the fuel out like you did but now I know it might have a reverse effect.

Anyways, sounds like you have a good start at where to look to troubleshoot your car to pass smog. Hope it passes on its next test! Make sure to drive it pretty hard for a good 20-30 minutes and get the engine real hot!

I'm going to try getting someone like Ivan to tune it before I start pulling parts out. If I do that then it's the carb first (which shows no sign of ovehaul otherwise), then the ACV, the the cat,....

If you still have your stock heat shields underneath I'll be crossing my fingers that you won't need to cut some of the hangers because the tiny bolts don't budge even with PB Blaster and get rounded lol.

if the car hasnt sat around long enough for fuel to turn solid (3-4+ years) then its not the carb.

ACV is a common failure, really easy to check. theres a big hose from the side of the acv to the side of the air cleaner, if there is air coming out of that at idle, ACV isnt working right.

The ACV seems to be working right.

I'm starting to think that replacing the cat might be the best. Even if it isn't the actual problem it should cleanup the HC.

I can't believe it's the carb, since it has always. like now, run smoothly.

Since you were just a tad off from passing a new cat should do your car well! They do go bad over time and since the rest of your car is running smoothly hopefully your car will be passing the next bunch of smog tests!

The cat on the 83 was put in 4 years ago, but it was only $200 installed, so it may have been just a cheap aftermarket unit.

Sure wish I knew how this turned out: Bliffle, did you ever pass?

If he put a new catalytic converter, he should have since he was just barely producing a little more over the limit.

HCs are high when ACV is dumping out air from air pump

ACV directs air 3 directions. port air, split air (cat) and relieve (dump)

the problem can be vacuum or switching or relieve solenoids on rats nest.


so a simple test. remove the dump hose from ACV. rev the engine to 3-4k rpm. there should be no air coming out.

I am having the same problem air is being dumped into my air cleaner. Can anyone till me which solenoid controls this? Ihave a another on to check it with .I will also put on a different acv and see if that helps. Cal smog is ruff

Wear points on the ACV are diaphragm rupture, port clogging, spring failure, and wear on the bypass valve bushing (round valve on the spring) where the shaft goes thru it. The hole wears larger, starts leaking progressively larger amounts of air, which prevents it from opening right, and from building enough pressure into the injection circuit.

It's useful to re-grease that shaft on occasion, even though it's not a maintenance item. Once the disk wears away sufficiently, the valve's done. No replacement available, as its retainer is swaged in.

does this only apply to 12a?

all rx-7s had air control valves if that's what youre asking

My info was specific to the SA ACV's, though the design concepts appear similar on later units.

i can't wait till our cars don't have to be smogged

i thought in cali they changed the law that only pre-1975 cars are smog exempt so our cars will have to be smogged forever

They did. Thank you, Arnold "my balls are in Maria's eco-friendly recycled purse" Schwartzentraitor.

Man I hate to hear abot this smog mess. It seems like such a pain for a car that is almost 25 years old. The technology was not top of the line back then, so I dont see how they think all of a sudden its just going to conform to todays standards.

They are not particularly interested in it complying at all; the government would much rather see us all driving brand-new cars, partly because they are cleaner, and partly because that generates the maximum in tax revenue for them, and makes their union taskmasters happy.

The fact that it is our money, our cars, and our state, does not concern them overmuch. They are interested only in the "greater good..." greater, for them, that is.

divindriver
 

Could you explain your post starting out " wear points on the acv ...." ? It was way above my limited knowledge but sounded relevent to my problem. My cat on my FB is shot and so was my Shutter valve. Replaced shutter, haven't tested the acv at the air cleaner yet, Boyee is helping me.

it did pass. it needed an intake gasket. my friend who did the work also has an N249 acv on his toolbox, so i think it needed that too.