rotorpower27

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….

celbii

iTrader: (2)

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

RETed

Why don't you post the actual numbers?


-Ted

rotorpower27

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

rotorpower27

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.

RETed

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

j9fd3s

iTrader: (3)

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

13b_cookie_monster

iTrader: (14)

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?

lax-rotor

iTrader: (1)

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

jackhild59

iTrader: (7)

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!

rotorpower27

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.

rotorpower27

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

rotorpower27

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

jackhild59

iTrader: (7)

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.

jackhild59

iTrader: (7)

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

HAILERS

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.

rotorpower27

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

rotorpower27

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

misterstyx69

iTrader: (142)

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.

hurleysurf24

iTrader: (3)

just tack weld on 2 extra cats for the day

HAILERS

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.

lax-rotor

iTrader: (1)

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

HAILERS

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.

rotorpower27

any other ideas besides just replacing the cat?

PvillKnight7

iTrader: (16)

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.