WOW, So I finally took my new 7 to get emissions inspected and.....YIKES!!
the limit for Hydrocarbons is 220 PPM and I'm at 1629 PPM. The limit for Carbon Monoxide is 1.2% and I'm at 6.1%. The car runs ok, the only problem I've noticed is that most of the time the idle is poor. I'm getting new plugs and wires. I've also seen a lot of ppl say to adjust the TPS but I don't have the light tester thing that you need. Anyhow, if anyone can give me some pointers or common causes, that'd be great. If anyone lives in the Nashville area and could show me some things, that'd be even better. I'll buy ya lunch.

Thanks everyone

 

Your car sounds just as bad as mine. The only emissions removed on mine is the pre-cat and I still failed the test miserably. It's a good thing I have the hook up for a quick "fix" over here. I think there's a write-up on how to pass emissions with a 7 somewhere here if you want to do it the legit way. Check the FAQ.

 

ok...I ran a bottle of prestone fuel system cleaner through, then did a tune up. I put in new plugs and wires adjusted the idle fuel to full lean, adjusted the idle air to bring the idle rpms to about 850, and adjusted the TPS. I checked the BAC, Air pump, AFM, and vac lines. I retested yesterday and I'm still failing...

HC is now at 704 PPM and CO is now at 5.16%

Any ideas?

 

Your cat is bad. You get a new cat and you should pass with flying colors.

 

In the FAQ for FC there is a table on what needs fixing based on what your emssions tests come out at.

Always read the FAQ for FC sticky thread (found at the top of this, the 2nd gen technical section) before posting. It has the answers to many commonly asked questions... such as the one this thread was started with.

 

I already replaced the entire exaust from the reactor back including a new o2 sensor. I already read the FAQ which is a little vague on this subject. I already adjusted the variable resistor as far lean as it can go and adjusted the air/fuel mix at the TB with the screw on top. So, I'm guessing that there is a bad sensor or valve somewhere but, I'd just like to know if anyone had a good idea on where to start. Also, I don't really want to try and run alcohol through an engine with 197,xxx miles on it; Besides being hard on the engine, it won't actually fix the problem... i'll still continue to run a rich/high maintenance engine and possibly wind up carbon locked.

There is ten tons of emissions equipment on this thing so, if anyone can think of a part that is likely at fault... please let me know where to start looking.

Here is a list of parts that I have NOT checked yet:

AAV
ACV
Air Bypass Solenoid Valve
Pressure Sensor
Charcoal Canister
ECU
Dashpot
EGR Solenoid Valve
EGR Valve
Intake Air temp. Sensor
Pressure regulator
Pressure regulator control solenoid valve
PCV
Relief solenoid valve
Switching solenoid valve
Water thermo sensor
Water temp. switch

 

what is vague? For your symptoms (High HC and High CO) it says check your air/fuel ratio and that the air injection (read air pump and ACV) is working correctly.


the air fuel is not on the throttle body, but rather the idle control is. Sounds like you messed with the idle and the variable resistor. How did you bring idle up when you cranked it down on the throttle body???

extreamly doubtful
half those things are not even related to the symptoms you have. Are you sure you read the FAQ for FC sticky threads chart???

Have you checked spark plug condition??? Have you checked fuel and air filter condition??? Have you checked air pump operation??? These should be checked long long before 99.9999% of those things.

Again if you have high HC and high CO, you are running rich (easliy seen on the spark plugs) or your air pump/ ACV are not working correctly. This is covered in the FAQ for FC.

The EGR (BTW) only controls high NOx, which you didn't mention.

 

Ok then, maybe I'm just stupid. I assumed that by adjusting the screw on top of the TB I was opening or closing the butterfly(s) thereby allowing more or less air into the engine at idle consequently adjusting the Air/Fuel mix and the idle speed. I turned the Variable resistor to full lean, then opened up the butterfly(s) (as I understand it). By Vague, I meant that High High Low = Rich air/fuel and/or air injection is only a statement and does not tell me where to look unless of course I'm smart enough(aparently I'm not) to figure out that air injection = smog pump AND ACV.

SO, since I was not smart enough to think of the ACV when u said air injection...My fault, I'll check that and thanks for the help.

In the future though maybe you could just say "check your ACV". I think that would be easier for us both. lol

BTW...I was just listing off all emissions control stuff to jog ppls memory. I repair machines for a living and sometimes things that aren't supposed to affect other things can and do in the strangest ways.

 

After giving it some thought for a few minutes...I may understand how the air/fuel is NOT adjusted by the screw on top of the TB...I assume that the ECU compensates for the increase in air consumption by reading the signal from the afm. Thank you for straightening me out on that. But, in that case...is the variable resistor the only way to adjust the air/fuel? Also, I don't see a section in the FAQ referring to the air pump and ACV...do you mean to refer to the FSM?

The spark plugs and wires are brand new...put in last weekend. Air filter is also a brand new K&N. I already checked the Air Pump and it seems to be working fine. After the exhaust and o2 these were the first things I checked. I will check the ACV as you suggested and post my results.

 

Ok. Having trouble with terminology here. Did you replace the catalytic converter or not?

Also, what are your NOx number? Rotaries tend to be high in hydrocarbons and low in NOx by nature. Modern computer controlled piston engines (especially OBDII) engines are cleanburning and are much lower in HC's and much higher in NOx when compared to our rotaries. Since your rotary is naturally low in NOx you could pass the NOx standard with the cat not working. You would be in the middle to low end of the NOx range with a well tuned rotary and a failing cat. If your cat *is* working the NOx number will be low double digits or single digit.

The front half of the cat works on the NOx while the back half works on the hydrocarbons and CO. The 3-way cat on the rotary breaks the oxygen off the nitrogen and makes that oxygen available to oxidize the hydrocarbons. There is not enough available to supply all the oxygen needed for the hydrocarbons, so the system uses an airpump to supply extra air (oxygen).

If everything is working correctly on the car, and you have done a tune up and you have replaced the cat, then I would suspect the airpump is not pumping air to the cat. The suggestion to temporarily hook the airpump directly to the cat is a good one if that is the case.

If you haven't replaced the cat, you really need to do this after the tune-up.

Here is the thread from my testing. Read it all and look at the numbers on my tests. You may find some help there.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/emission-testing-texas-style-465422/

Good luck!

 

Yes, I replaced the cats. So far, I'm assuming that Icemark is correct about the ACV which from what I can tell in the FSM controls where and when air is sent from the Air pump. As far as connecting the air pump directly to the cat...I would prefer not to rig anything here...as a last ditch effort, if I cannot find the problem I may do just that. There is no measurement for NOx here. They only measure Hydrocarbons, Carbon Monoxide, and Carbon Dioxide.

 

There are two screws on the throttle body. Neither shoudl be messed with unless you want to change your idle OR the TPS readings.

The screw towards the back/firewall is the hardset idle screw. You need to get it to 800 rpm. Screwing it "in" will raise the idle.

The other screw is on the throttle lever. You should not mess with this since it will change your TPS readings. If you have then you need to get a multimeter and spec it out to the correct readings now. Search the forum for TPS adjustment to find out how.

The main/minimum things you need to pass are....

Air pump
ACV
Main Cat.

The cat will do a lot of the work AS long as it's getting air.

I modified my ACV to pump straight to the cat 24/7 and passed beautifully.

I failed the first time because the airpump had blown off it's hose to the ACV. As soon as I connected it , the readings all drastically dropped and I finished.

If your interested in the ACV mod I might be able to get some pics of what I did tonight.
It is a 10 minute job.

 

Yes the variable resistor is the only way to adjust lean to rich in the combustion. You can have clogged filters, misfiring plugs or other issues that can contribute, but the variable is the only adjustment at idle.

BTW they call the screw on the top of the throttle body the $1K screw, as it will take you about 100 hours for a mazda tech to get it set right once its been tweaked.

As far as info on what to look at, in the Emissions section of the FAQ for FC, tehre is a table. You can simply look at what you are high in, and that will point the way to what needs fixing. It is real simple.

When asking about spark plugs, I was asking about the condition. Do your old plugs have lots of black soot on them and look wet or shiney??? If they do, then you might really be running rich. If they don't; then your engine is not running rich, and the problem is related external to combustion (such as air pump, ACV, Cats, etc).

 

Icemark, yes the plugs looked as you described... but that was before I leaned the mix. I just got finished testing the ACV per the FSM...It blows air out to the silencer 100% of the time even at idle and does not blow anything out to the cat when I disconnect the vac line to the switching solenoid valve. I guess that's my problem. Thanks guys. I'll post test results after I replace it.

 

CRAP.....anyone know where I can get an affordable ACV for an 88 n/a mt? The wife is gonna shoot me if I tell her it's $400.00.

I thought I'd ask before posting on the F/S section... I'd prefer a new or rebuilt one but if I can't afford it....I'll take what I can get.

 

I find them on ebay all the time for $10-$20,

but make sure its not just a burnt solenoid in it (there are two).

If it is a burnt solenoid you may need a ECU as well as a failing solenoid tends to take the ECU control circuit for it out.

Or just jumper the air pump past the ACV an be done with it

 

If I bypass the ACV wouldn't that cut the supply of air to the exhaust port and render the reactor almost useless and possibly cause excessive wear on the main cat? If you don't think this would create a problem...I may do that at least until I can find a replacement.

 

no, just run the output from the air pump full time, direct into the split air pipe/cat.

The only thing that is bad is that it will take longer to warm the cat up to operating temps and the cat will run slightly cooler at constant highway speeds of less than 70 MPH or so.

Its not a perfect fix, as the ACV tends to also help stop after burn popping in the exhaust manifold, but it will let you pass emissions until you can find a good working ACV.

 

I quote these guys...

http://www.aircarecolorado.com/repair/fixesfor.htm

"Although the rotary engine is very different internally, control strategies and external hardware are comparable to its reciprocating engine cousin. Check for the following:

1) Air injection system function-switching;
2) Thermal reactor/catalytic converter burnout.

The carburetor on this application is relatively dependable. Rejetting is not recommended. If a rotary fails for hydrocarbons (HC), with low CO and a good ignition system, suspect worn apex seals on the engine rotors -- this situation is analogous to low compression in conventional engines."

If I were you, I'd lean the idle mixture setting, retard the timing as low as you can go and drive the car to the shop with the oil metering line discoed prior to getting tested. Should lower both readings.

or you could slip the guy a 50$.... ~rich

 

ok, since the ACV was always pumping to the silencer..I just ran a hose from the silencer outlet on the ACV to the split air pipe and retested today. Here are the results:

Hydrocarbons measured in parts per million: 6 PASS
Carbon Monoxide: 0.09% PASS
Carbon Dioxide: 12.94% no limit

From 1662 to 6...now THAT's improvement!

Thanks for the help guys!

 

grats!

 

I noticed that the ACV's that Mazdatrix sells are specific to year, aspiration, and tranny....Is it really going to matter or can I just get one off any 86-91?