1981 New plugs, air filter oil change etc

The numeric printout shows I passed CO (25gr/mi limit 30) but failed HC 1.8 gr/mi limit 0.8). If you look at the graphical data the CO dosen't look good.

Any suggestions, the attachement shows the grams per mile on a rolling dyno. The dark line is vehicle speed, the flat line is the limit and the light grey line is the measurement from the exhaust.

The cat is aboput 4 years old. When I got it inspected then it failed and I found the air pipe rusted off the side of the converter. It passed 2 years ago no problem.

My first step was to look at the float bowl levels and put a carb kit in. That however sounds like work.

 

If your CO is OK,it means the air/fuel mixture going into the engine is good.CO content is a direct indicator of your mixture.Left over HC is unavoidable since no engine burns all its fuel.It should however, consume most/all of the availible oxygen in the intake mixture.
Rotaries leave unburned HC due to thier long combustion chamber.Good CO and bad HC is almost always an indication of a bad cat,provided the air injection system is intact and working.
Is your newish cat a generic one, or a rotary specific cat?(Bonez,Mazda)

 

It is probably a generic Cat but it does have the air pipe on the side, something I've only seen on rotaries.

To test the air injection should I feel air when I disconnect the tube into the cat?

 

high HC is an ignition problem or a lean misfire.

 

that is why I always pay off someone to pass me

 

You can check it at the air pump, it's easier, then check that the system is intact to the cat.

 

I've done some checking;

There is a vacuum at the pump inlet when the engine is running.

The fuel level in the front is about 3/4 of the way up the window and in the back is about 1/2. Is the front ok?

Does anybody know what "Choke Pull-Off: CARB. TYPE: N-4 " does? It is obvious it hasen't moved in quit some time. here is a picture.
http://www.partsamerica.com/ProductD...pe=275&ptset=B
I should add the choke plate on the top of the primaries is fully open.

 

You were right!! The old cat (5 years old) had a hole burned through the first section. I welded falnges from JC WHitney on a generic Walker 15031 three way catylist with air. It passed. I think i'll put the old one back in till next inspection.

 

ok i had this same problem, have them do the test manually, so the computer dont tell it when to do stuff. but anyways when ur engine gets nice and hot it will pass. i had the hardest time doing it for mine, i took it to the place at least 7 times before it finally passed.

 

I don't even have to pay anyone off. I played my cards right with his daughter, and became good friends with the family. =P

 

correct there,for future refference,do that! keep that cat only for inspection time,use an old one or none the rest of the time. rotaries chew up cats,period! and,ive found with my gas anylyzer that the berrymans emissions additive actually does work,slightly,but in many cases enough to pass it,and if you dont pass it,they will refund your money! no i dont work for them lol. the only other thing is make sure its fully warmed as stated above and youll rarely have trouble passing.