Trying to pass smog. 8 months of failing
 

Alright before anyone just say's "go search”. I have over and over again

I have had this issue for over 8 months now.
Car is running to rich to pass smog.
HC and CO levels are to high, NOX levels are okay
(do not post J-rats tricks)

For reference my car is a 1988 GXL NA
About 2k miles ago I rebuilt my engine due to an oil control ring failure. While I was at it I ported the motor. You could call it a street port but it was more of polishing the casting more than anything.

Now on to making the car run right.
I checked the ATP and boost sensor: both were fine and functional.
The TPS is also functional and dialed right at 1 ohm.
Replaced all vacuum lines when motor was out
Cleaned and flowed fuel injectors, new fuel filter, fuel pressure regulator is perfect.
New spark plug wires (NGK).
BAC functional
EGR functional

Things I have checked that were bad:
I knew something was wrong when no matter how I drove the car I would get 14mpg.
I found out the AFM carbon stripe is almost completely worn down, so it was giving erratic reading to the computer, basically the AFM was telling the comp I was floored going up a hill all the time. I have fixed this problem, and it reads perfectly. Which made a huge difference to the cars drivability. Also checked the air temp sender in the AFM: perfect.

Changed spark plugs just the other day to Denso sd31a all around. I’ve been running the standard NGK stock plugs, but I have noticed a considerable difference with the new plugs.

Alright so my questions are:
Does anyone know why my car is still running rich?
Or
How can I make the computer run the car leaner?
(messing with AFM does not work, or messing with the ATP)

im sure im leaving something forgotten….

Not trying to hijack, but how do you check the afm carbon stripe, seems similar to what mine is doing mpg wise

Why don't you post the actual numbers?


-Ted

my #'s have been around this roughly. ive been many times and this is has good as it has gotten.

HC =140-160 (max 120 low speed 96 high speed) used to be up at 400+
CO = 0.80 (max .76 low speed .65 high speed)
NO = 100-200 (Max 700)

these results tell me it too rich

pull it off the car, read the fsm, check the sweep on the flapper.
if the numbers jump around then: open the black top, check the strip for wear with a magnifing glass, if you see carbon dust all over and the strip is worn then you have an issue.
what i did was clean up the area until it reads correctly.

Actually, those results tell me the car is running lean.
When you lean out the mixture, the NOx skyrockets, and this is exactly what the numbers tell us.
If it was rich, the HC's would be really high.

As for the other numbers, you're very close to passing.
Since we're dealing with a rolling smog, double check your O2 to make sure it's working correctly.
Also might want to double check your ignition timing...


-Ted

o2 sensor has a big impact on the mixture

also the air pump air MUST go thru the air control vale into the EXHAUST ports, if you rebuilt the engine and swapped the rotor housings front to rear it blocks this off and it prolly wont pass no matter what

from what i heard i thought a streetport and emissions don't mix... once your port it its far from passing... because i wanted to street port but i dont want to worry about emissions... hows your cats?

Did you replace the Vacuum line going to the Boost Sensor? If you did, that might be part of your problem.

No, these numbers tell you that your catalytic converter is NOT WORKING.

Your NOx would be low double digits if it were working...

Your CO would be something like .05%

Your HC would be low double digits.

Seriously, I think your results speak to a car that is running pretty well, but the cat is shot.

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

Good Luck!

the NOx levels are low and used be lower around 20-50 during which the HC were at 400.
when the car was in that configuration it was really boggy, now with the HC considerably lower and NOx higher= leaner, it much more like it should be.
correct me if im wrong.

i have replaced the O2 sensor already (denso exact replacement)
before i fixed the AFM i hooked a scope up to the O2 sensor right at the computer and looked at it under driving conditions. i plan to do that again now that the AFM is functional. before it was just pegged to full rich.
i have an excel spred sheet of the measurements from 1st gear to 5th getting on to a freeway, very interesting, if you want to see it.
timing is spot on. i tried advancing it on the dyno, but it had little affect to the #'s

i made sure the housing went back in the right places

no i did not replace the vac line, but i dont believe there is a pill in it though.
what size pill should be in it, if thats what you are referring to.

i replaced the main cat already, this only had an effect on the NOx levels, that i can easily verify with old test results prior to replacement. from my understanding thats what the cat is really designed to so. High HC is due to un-burnt fuel or misfire, both of which a cat wont fix.
but the two precats are still stock and most likely shot

im not trying to come off sounding like i know everything, because i know i dont. just looking for solutions

You don't fully understand what the cats do. The front brick reduces the NOx into N2 and O2, the back brick reduces HC and CO into H20 and CO2 using the extra O2 from the front reaction as well as O2 from the air pump.

From Wikipedia:

Three-way catalytic converters

A three-way catalytic converter has three simultaneous tasks:

1. Reduction of nitrogen oxides to nitrogen and oxygen: 2NOx → xO2 + N2
2. Oxidation of carbon monoxide to carbon dioxide: 2CO + O2 → 2CO2
3. Oxidation of unburnt hydrocarbons (HC) to carbon dioxide and water: 2CxHy + (2x+y/2)O2 → 2xCO2 + yH2O


Make sure that the air pump is moving air into the center of the converter at the appropriate times; if you cannot verify this, then you can directly connect the airpump to the converter. Some say this is only a temporary fix (Hailers) others say the car can live this way (Kevin Landers). I say, if you can make it work right, why not do it?

If you are getting that level of unburned HC out the back of the pipe, and the NOx is at the stated levels, then you have likely melted your cat with the previously mentioned problems. If the car truly runs so rich/misfire it will melt the ceramic in the bricks. The cat should be replaced only after all the other systems are verified, otherwise the same problem that fried the original cat gets the replacement. You may also have had debris from the front cats continue to pass into the new main cat, contaminating, clogging and abrading the brick(s).

In other words, you may have to replace the cat again.:(

In CA you have visual, so you cannot remove the front pre-cats. Remove them and hollow them out, leaving the casings in the system. Then replace the main cat with a high capacity 3way w/air cat. Pick one with a carb number. :)

Hey, I may come off sounding like I know it all as well. Just trying to help.

Seven months is a long time to be frustrated. Read my thread, look at my old numbers. They look a lot like yours do. My old cat was verified as working at the muffler shop.

https://www.rx7club.com/showthread.php?t=465422

You might try this site to figure things out: http://www.aircare.ca/index.php?repinfo-ere-causes.php

Also make sure the ACV is working and sending air to the exhaust ports etc. and not dumping it overboard to the silencer in the right fender.

02 can't be the problem at idle only driving.

The TPS should output one volt dc when the engine is HOT and up and idling. The TPS determines when the Relief and Switching solenods open and close. Those two determine where the air from the airpump goes INSIDE the ACV.

Pin 2G on the ECU or the green/red wire at the tps's connector (harness side not tps pigtail side).

The cheaper catalytic oonverters are not meant to last more than about two year or so. Says so on their sites. They have less material inside than the stock ones.

EDIT: I missed the post by JACKHILD59 above. His says it all. He's the guy who sat in front of me in emissions class and I copied off his papers.

your thread has been helpful.
you seem to me that your running really lean, getting 24 mpg is crazy to me, i get 18 on the freeway at best, 14 in the city.
oh and i would pass in texas, my car could pass under those #'s
so do i need the two pre cats to be functional?
the first one is empty, the second is intact but useless...

this is the cat that i bought, that has been on the car. is this is correct part?
http://www.performancepeddler.com/de...CT_ID=MAG23688

i will check my TPS again to make sure everything is okay there.

Throw a NEW catalytic on that Baby..It Screams Shot Cat..YOu can get by with What you Posted..IF it is new..you can also Rig up one that is For a V-8 Engine,as long as you have that Split air Pipe going to the Cat..One of the Tricks of the Test is to GO Driving the car about Twenty minutes before you get to the test,,Doing some spirited driving.That gets the cat Hot,and when it is hot,it does it's job better than it would cold.

just tack weld on 2 extra cats for the day :D

http://www.autopartswarehouse.com/se...20Mazda%20RX-7

There's a part there 4689 for RX-7 that includes all three catalytic converters.

But I've gotten by with the 4489 all by itself before.

I was told there was:
http://www.mazdatrix.com/getprice.as...m=13-9860-8931

http://www.mazdatrix.com/getprice.as...m=13-9860-8931

That is the orifice that goes in the boost/pressure sensor line. I kinda doubt it's messing with your emissions problem. But I'd get one if you don't have one. Or make one.

any other ideas besides just replacing the cat?

Rig a high volume electric air pump like a vacuum cleaner run on reverse and wire it to force air constantly into the middle of the cat.

88NON TURBO...........Fully warm up the engine. Idle the car. Pull the large black hose off the bottom of the ACV. Feel for air. There should be only a minor amount of air coming out that large nipple.

Now pull the BLUE electrical plug off the relief solenoid on the other side of the engine. Now a Large amount of air should come out the large nipple on the bottom of the ACV. Proves the solenoid is working and part of the ACV is working.

Put the elect plug back on. Now at idle, pull the two vacuum lines that are just above the ACV off. One at a time. Both vacuum hose should have a vacuum on them. Feel for it with your fingers. IF both have a vacuum, that is good. Put the hoses back on.

Now at idle feel for the air coming out the bottom large nipple. Rev the engine over 3800rpms. At approx 3800rpm the air coming out the large nipple should really blow out hard, proving the relief solenoid is working and the ECU is operating the swtching and relief solenod and acv right.

What you also might do, is look at the voltage coming from the 02 sensor at idle. It should be close to zero. Now pull the plug off the blue relief sonenoid. Now the 02 sensor should read rich. Like 0.7 or 0.8vdc. Because NOW there is no air going to the exhaust ports located prior to the 02 sensor and the airpump air is now being sent overboard into the right fenders silencer.

If the ACV works as above, then it is the catalytic converter gone kaput or a seriously malfunctioning engine running too rich. You know there is a variable resistor on your car? It controls idle mixture. It has a R and L screw that mean just what you think. Turn to L til the engine starts stumbling a touch and then back til the engine is steadier at idle. Might help. Might not. Just a main cat should do the job if things are right with the engine..

Try a diffrent smog shop!

My buddy bought a TII in santa cruz. He tried to smog it there and it wouldn't smog. Came to humboldt and it passed no problem.

Mileage isn't a good indicator; I can drive my Vert and get 10mpg in the city and 15 on the highway but then I attract every law enforcement official in a 500 mile radius...

At what stage of your odyssey did you replace the cat? I am afraid that if you replaced it prior to all your other fixes, you may have cooked it.

I have trouble believing the cat is working because the NOx numbers would be very very low. Rotaries are inherently low NOx producers. My front brick, the one that reduces NOx was completely crumbled and still my NOx was a pass. Your NOx numbers look like the cat is not working at all.

The two front pre-cats are intended to heat up and light off very quickly after startup, reducing emissions during a cold start. You do not need them to function to pass a sniffer test. You do need them to pass the visual portion of the test. Just remove them and completely gut the housings, then reinstall.

The cat I used is universal and was sized for a very large V8 engine and a large vehicle, 7.4 L (460 ci) and 7000 lb.
http://www.autozone.com/selectedZip,.../selectZip.htm

The theory was told to me by Jerry at Jerry's Muffler in Lewisville, TX. Jerry is a stand-up high performance exhaust guy (He also does a helluva good job with high performance 4 wheel alignments) Jerry told me that ALL modern brick type cats are by default high-flow design. He said that what I needed for my Rotary was a high flow and HIGH CAPACITY cat-that way the bricks would be larger and beefier spreading the reduction and oxidation reactions over a larger surface area. This would effectively reduce the surface temperature on the bricks, thereby extending the life of the cat. It was good advice. I am on my third test with the same cat, 2nd year of actually running on the car.

BTW, in case i hurt your feelings, Santa doesn't really hate you. :)

It's best to check it with a lab scope, and since most people don't own one, it is usually checked with a multimeter. You can do a resistance check or a voltage check, either one will do. Since you're local I can check it with my lab scope if you like. Send me a pm if you're interested. I can also show you how to check your coolant sensor and both IAT sensors

thanks everyone
 

alright, well i guess i need to slap some money down on a big beefy cat then....
ill let you know what the results are, thanks for the help :D

honestly i could care less about an rx7, i just love the motor. look at my avatar, i deal with a v8 enough already

just a thought but you may have fried the first replacement cat if you went too lean or something, i DISTROYED a bonez highflow cat, less than a half year turned it itno dust and element rattling in my exhaust.

once again
 

Alright i cot another cat and welded it in front of the main cat.
Problem is it didn’t really change the number that much.
i still feel that my motor is consuming to much fuel, and that is why my hydrocarbons are way too high.
After running my new setup the new cat, which im going to cal a pre cat. got very hot, to point of glowing red, i dont want to destroy this cat.

basically im looking to run leaner so i can pass smog, any suggestion on this would help.

pictures of my new setup

(the first pre cat is still on the car, but it has no brick in it)

http://i104.photobucket.com/albums/m...1608_1622a.jpg

i failed smog 2 times the 3rd time i passed...what i did was get new cats....(2 new cats)....it made a huge difference on my numbers...hope this helps.


[edit]

oh wait you already did that...hahaah..sorry i was too slow..

the money you spend repairing your car for smog, passing , failing.. you could find someone and pay under the table...

unfortunately this is true.. sucks for our environment, but you could spend tons of money on repairs..

always good to have friends..........................
who said that?
seriously, start making friends with the smog people. good enough where you can ask certain..........questions..........hint hint..........cough cough.........
might be a bad idea though

peace

How I Passed
 

this is what I did

8 gallons of gasoline
2 gallons of methanol mixed in the tank


results
15mph HC 10 CO .03 NO 49
25mph HC 17 CO .12 NO 29

passed with no problem

PS. the ratio is critical, I first showed up with 4 gall of gasoline and 2 gall of methanol, the car ran like shit and wouldn’t run stable on the dyno

As for anyone who wants to try this method just remember that Methanol is corrosive to aluminum and should not be left in the car for any long period of time.