Trying to pass emissions with my 10th Anny. Haven't had to actually pass emissions with this car yet as I was living in NC and they only check to see if you have all the original equipment.

Now living in NM I have to pass the emissions test and have failed miserably on the low end.

High Speed 2500rpm
HC 371 Limit 200
CO 2.78 Limit 1.20
CO2 13.4
O2 0.07

Low Speed
HC 1089 Limit 200
CO 2.03 Limit 1.20
CO2 13.1
O2 1.18

For this latest test the car was setup with the air pump connected directly to the catalytic converter, denatured alcohol was added to the gas, and I had replaced the spark plugs, adjusted the TPS, idle speed and mixture.


For tomorrow's test I have replaced the O2 sensor and swapped out another MAF sensor from my previous turboII that had been used when it successfully passed emissions a few years ago.

So I am just looking for any suggestions or things that someone might notice from the results from the emissions test that I can do to correct what ever is wrong.

Perhaps the Catalytic converters are just too old?

 

How many miles on the cat?

 

Assuming it is the stock exhaust from the same car it would have near 90000 miles on it.

 

1.) install new cat

2.) pass emissions

 

easier

1. make air control valve work correctly

2. pass smog

 

move to illinois? no emissions on 1995 and older vehicles.

i would say buy a new cat..

 

Jack is right.,If the cat has 90 THOUSAND miles on it,It went for a Dump when Christ was a Cowboy(long time ago Bubba)..Get a New Cat,your CO2's Show that.

 

Well I tried to bypass the ACV altogether to make sure that air was being pumped to the cat...would connecting the ACV back up work better for some reason?

 

1.) Fix your car.

https://www.rx7club.com/showthread.p...emission+texas

 

Those limits are actually pretty high. They are higher than cali or texas.

Being that they dont test for Nox you could lean it out a bit if you had some kind of engine management to lower your hydrocarbons and carbon monoxide. But if you dont have engine management I would just buy a cat that you can install only when you go to take your emissions test.

 

try with a new cat and o2 sensor first. the ACV is going to inject the air into the exhaust ports (before the O2 sensor) depending on the running conditions, leaning out the mixture before the air enters the cat at all. it won't necessarily solve your problems.

 

new cat first, that will most likely do it for you by itself. But you can also gut the ACV so it dumps a ton of fresh air in to the exhaust ports and cat, this will dilute the exhaust gasses a bit as well.

 

Make sure you save the receipt for your new cat. Many states offer an emissions waiver if you spend enough money on emissions-related repairs and the car still does not pass for some reason. I've never lived in New Mexico so I can't tell you if that's the law there, but it may be.

 

yes. pumping air into the exhaust ports works much much better than pumping air thru a 3/16" hole into the back half of the cat

 

Well I think I am going to get a high flow converter and weld some flanges on it to replace the first muffler on my racing beat full exhaust system and just get rid of the stock exhaust all together.

So my next question is do I need to get a cat that has an air tube port on it?
Or can I just get away with re-connecting the ACV in stock configuration and just leave the block of plate for the split air tube on the manifold?

 

LOL wtf.....

I agree. New cats would probably solve your probem.

 

Well, with how rich rotaries run, you may want to get a cat with a split air tube and hook it up if you are going to be running it all the time. If your just going to install it for emissions testing purposes then don't worry about it.

 

Depends what you want to do. You need the air (oxygen) to the cat to pass. You can do it temporary, the remove or you can redo it to stock standards and live with it. Note: This method is called "fixing your car".

There's lots of marginal-to-bad info being posted here.


The supply of air into the exhaust and preferably into the space between the bricks is necessary to provide oxygen for the Oxidation reaction that occurs in the rear brick to Oxidize the hydrocarbons.

Note the emphasis on oxidation. You need oxygen for oxidation. On our FC's, it comes primarily from the air pumped into the exhaust (on rotaries) and from the NOx reduction reaction in the front brick. Rotaries have inherently low NOx due to the relatively slow combustion speed and relatively low combustion temperatures.

So, on our rotaries, controlled by 1980's era technology, the pumped air. (exhaust and split air) is necessary to successfully oxidize the Hydrocarbons.

I recommend a universal 3-way w/air cat. The one I use is available from Autozone, part number is 38734, brand is Maremount, 2-1/2" inlet/outlet rated for a V-8 of 7.8 liters and over 8000# vehicle. I have passed emissions 3 times with this one cat. In a couple of weeks, I will try it for a 4th time.