AAHHHH! rotary gods, save this thread!

in short: mazda emission engineering is a PITA!

BTW: rotary resurrection; CHECK UR PM'S i want my s4 gasket kit! haha

 

...and I thought this was only a problem with Wives and Girlfriends...

 

interesting... so you dont need to run the cat on the day of the emission check???

 

************************************************** ********8
No. Port air is injected to create a afr closer to stoic because the converter is more efficient when the air fuel mixture is at stoic. That's why air is injected in the exhaust ports. Converters don't like raw gas. They fail with a too rich mixture. Early failure is the result of a too rich mixute.

And air is not sent to the split air pipe all the time. Your plumbing the split air pipe wrong and the result is, someone is going to follow this bullshit advice and ruin and expensive new catalytic converter.



The cat works better at hwy speeds because the 02 sensor is working in conjunction with the ECU to put out a stoic mixture. Cats work better with a stoic mixture.


**********In the short term, it can likely do without the air pump altogether if it is nice and hot for the*********

UTTER Nonsense. Whats going to result in sending fresh air to the rear secton of the cat, is that it's not going to burn all the emissions and it's going to clog the mesh up. Sooner or later, and probably sooner than later, that mess is going to burn up, and it isn't going to be the controlled burn of a normal catalytic converter. It's basically going to turn into a large, expensive brick turd and about as usefull as one.

****jackhild59 ...and I thought this was only a problem with Wives and Girlfriends **** What? Words from the peanut gallery? Yeah. I know. You and AGreen (got that moniker a bit wrong, sorry) are the REAL converter knowledgable guys.

 

^ thanks for the tips, i'm glad the last owner left most of the emissions intact on my TII

 

Hey, when you and Keven are discussing technical details to this depth, I just sit back and learn. I feel like I am in back in school. I wasn't the class clown; I was the guy that sat behind him and got him in trouble.

Back to the peanut gallery.

 

I put my cat on. Get all the ACV crap back on and working, re-tune with my rtek and take it to emmisions. The next day I pull the cat back off and block the ACV and re-tune. Tuning is easy as it only effects my idle and I only chang one cell inmy rtek. No risk of ruining the cat, it has about 1000miles tops on it as I was lazy when it was first on my vert.

 

i realize i'm new here, and probably stepping in a bit over my head, but....couple things:

1. No manufacturer ever tunes an engine to 14.7:1...ever. 14.7:1 is the ideal ratio, not the standard. there would be more grenaded motors everywhere if this were the case. it leaves no room for error. granted this is a BIG generalization, but N/A cars tend to run about 12:1, and boosted engines 10-11:1 under load. Again, this is all under load, cruise and light throttle will be much closer to 14:1, unless you can tune, at which point you can get 14.7 or higher at cruise....

2. A rich exhaust can and will fail a convertor quick, as will a severely lean condition, at which point you nuke the honecomb in the convertor and basically clog it with melted matrix.

3. depending on your situation (getting more on topic), an dyour state, and the testing process, you can pass with no actual convertor, provided you have a shell for inspection (if req'd) and a basic means to tune. there are a ton of ways to fool an emmissions test, but it all depends on what you need to fix. Too many Hc's? lean the car out a bit, or run a bit of alcohol in the tank (not recommended here). CO to high, NoX (if tested)there's a solution for that. you should look at your initial inspection and see where you failed, do some research, and go from there.

If the easiest solition is to hook up th eemissions crap, then by all means, source the correct components (i'm sure they'd be cheap at the j'yard (minus the convertor)) and put it together.

 

"
If the easiest solition is to hook up th eemissions crap, then by all means, source the correct components (i'm sure they'd be cheap at the j'yard (minus the convertor)) and put it together."

Thats what I did for $45... had to get exhaust for $50 and cat/precat for $20... all I need is a belt then I'm off to test only... such a P.I.T.A. and waste of effin money. I coulda went to a drift event for that much dough! DOH!

 

I hate to bring back old threads from the dead but...

I was reading through this is and it chock full of inaccurate information, so anyone looking to keep their cats in good condition could be very, VERY misled.

Continuously pumping air to a catalytic converter is NOT what you want to do. Cats are designed to catalyze reactions (NOx to N2, CO to Co2, etc) and NOT as a combustion chamber! Pumping air to a cat when the engine is running AFR's much less than stoic (<12:1) will result in a very dead cat, very quickly. The air will mix with the rich conditioned exhaust gasses and litterally combust inside the converter, melting and clogging the mesh.

HAILERS has pointed some of this out, and understands why mazda has this system in place, and why port air is necessary (as opposed to continuous cat air).

 

My cat can whistle!

 

More armchair engineering at hand I see. What the stock system was designed to do for longevity of the cat, and what a few individuals need it to do 20 years later to pass a single test every 2 years and then put the mods back on, are 2 different things.

MANY people have passed the sniff test with an air pump, cat, air pipe between, and a bit of denatured alcohol in the tank. If any of us were truly worried about the design and function of emissions components over a long period of time, we would probably not be driving a rotary at all.

The people that would make use of this thread are trying to pass a temporary test with a modded car. After all, if you wanted to drive a stock car around, you dont necessarily need to know how every little part functions and how/why it was designed...you just install working parts and let it be.

 

Come on guys! It's Valentine's Day, where's the love?

I'll summarize this thread for any searchers. I think we can settle this by saying that Kevin's way (air straight to the cat) is probably the quickest and easiest to pass the test, but restoring the ACV at least partially (per Hailers) is optimal for absolute maximum cat life especially if you just bought one. BOTH WAYS will work if done properly but have tradeoffs.

Restoring the ACV:

-- longer cat life, although we cannot quantify exactly how much longer
-- more complexity of plumbing
-- probably better if you plan to keep the cat on there on a permanent basis (Cali cars for example)

Running the airpump straight to the cat:

-- less cat life, although how much less we cannot quantify exactly
-- simpler to do, no need for the ACV and its associated plumbing
-- best if you plan to just pass emissions tests and then take all the crap off

Also, for purposes of this thread, you MUST have a cat and an airpump hooked up in some way. Rotaries are not 4 cylinder honda engines that really could get away without a cat. The airpump is necessary because a rotary engine needs to idle at a richer AFR than a piston engine, and so you must hook it up either through Hailer's ACV method or straight to the cat per RotaryResurrection/Kevin.

 

I live in CA, and have a street legal 13b-rew swap, with a cheap aftermarket cat. I have found that NOT running any air to the cat when not trying to pass the test preserves the cat, even if running PIG STINKING RICH. I always read from people that it clogs the cat, I am here to say that that is false what clogs the cat is heat, there can't be heat if there is not enough oxygen to convert excess hydrocarbon.

The point, if you live somewhere that the cops can't give you a 2000 dollar fine and impound your car for not having a CAT than just take it off in between smogs.

But another option is to route air away from the CAT, or use an FD air pump that has the eclectic clutch, and keep air out of the cat between smogs.

The cat will last between smogs, the car won't pass without it, but it will cut down the smell way down and cut down pollution to maybe just 3 or 4 times the max limit for HC's rather than like 15 times the max limit.

 

If someone wanter the ACV to blow all the time (turbo???) there's better ways to do it than run a obvious non stock hose from the airpump to the split air pipe.

All you'd have to do is remove the Switching diaphram from the ACV. You could even do that with the ACV on the engine. Just four screws to remove. Then you'll see the poppet valve that covers the Port air hole.

You'd take the diaphram and remove its outboard cover to access the nylon looking diaphram. You'd get several washers with slots cut in them. You'd shove the poppet towards the diaphram.

Then you'd see the rod that connects the diaphram with the poppet valve. The slots you cut in the washers are made to slide b/t the rod and the front cover. You stack them so when you relieve pressure on the poppet valve, the poppet valve can't return to cover the Port air hole. Therefore when you put it back on the ACV air will always blow into the Port air hole. There's now nothing to stop the air from going to the Port air hole. This makes more sense if you actually remove the four screws for the switching diaphram and look at it. Then it Should make sense.

Or you could just cut the poppet valve off the rod if the diaphram for the switching diaphram is toast. You can't buy new diaphrams so the ACV is useless anyway. You'd cut the poppet off instead of putting washers b/t the diaphram and the valves body.

You'd also have to block one of the two hose for the relief diaphram for this to work and not dump air overboard at certain times. A simple 10mm screw/bolt with the head cut off and shoved up the line would do the trick.

The non turbo is a bit different.

By the way, on a stock car, there is NO air going to the split air pipe or anywhere else for that matter, during a lot of the driving. If you ever look you'll see the Relief solenoid is de-energized a huge percentage of the time, meaning the silencer in the right front fender is seeing a lot more air than the engine/exhaust. I think I wrote that before somewhere.

You and also kiss that new converter bye, bye because it's going to become useless in a few thousand miles.

 

JPG of parts: The IDEA is that if the Poppet isn't there, then there is nothing to stop the airpump air from going to the Port air port.

 

is the port air port go the stock exhaust manifold? honestly I have never messed with an rx-7 that has fully working emissions...

 

Air leaves the ACV and goes down the intermediate housing and exits into a triangular cavity on the rotor housings and enters a half inch hole that leads to the exhaust port. Same scenario for both rotor housings. That is a description of the Turbo engine. Non turbo has a different routing on a series four.

 

If both solenoids are powered, both the split air pipe and port air are being taken advantage, correct? I don't have my FSM sitting here so I can't confirm but I seem to remember this being the case on T2s.

 

\

I dont know about that... IF you are running the air to the PORTS the whole time, as opposed to the CAT, it might actually last a decent amount of time. A lot longer than running air directly to the cat, thats for sure.

The reason behind this is because the air to the ports will cause combustion in the ports and exhaust headers, aka before it reaches the cat.

So the bonus you get here is that you can pass smog with a stock look, while preserving your cats for longer than you would if you were running air to them continuously.

 

You could REMOVE both those solenoids and their poppet valves, and then reinstall them without the poppet valves.

Then you will have constant air going to the port air hole and I think the Split air hole. But have you ever notice how small those two holes are? The feed to the split air pipe from the ACV is a rather small hole. Same with the Port Air SOLENOID hole. Especially compared with the Large hole opening if the Switching poppet valve is eliminated or held open all the time.

Split Air SOLENOID is only energized in FIFTH gear. Port air Solenoid is a on/off hard to pinpoint when in either mode. Then again, you could energize them at will with a little wire........or just remove their poppets to do the same.

 

If you send air full time to the exhaust port then your gas mileage is going to drop significantly because your car won't be able to go into open loop when cruising.

 

Very much true. I can only defend myself by saying ............I was suggesting other ways to feed air from the airpump constantly to the exhaust. With the caveat that once emissions checked out, then it would be returned to a non functioning ACV again or removed ACV.

But now that I think of it, when the tester does the 15mph and 25mph test on the rollers, the ECU won't go into closed loop, like you say.

The afr will be??? undetermined unless you looked earlier at the afr at those speeds with no airpump action. But even if rich, the converter MIGHT be able to handle the low afr.........if it's a fairly new converter.

Then again, with a stock engine and ACV/Airpump, the afr seen is lean prior to the 02 sensor at idle and lower speeds. Because of the air from the airpump going to the Port air (exhaust ports). The ECU/O2 sensor isn't going into closed loop til the Port air is cut off from the exhaust ports. There's other angles to that.

 

My car is in closed loop at 500 rpm.

If you don't have a newer haltech then you don't know what your missing.

The stock system with a precat and main cat is splitting the thermal load between the two converts by using the split air system. Thats a major part of its function.

On the FD the airpump (as stock) is clutched like an A/C compressor, and its on an RPM switch that turns it off at 3500 rpm.

 

About that comment of mine about the ECU not going into closed loop at 15mph or 25mph. On a normal ACV that has not been fooled with, then the ECU will go into closed loop or might not go into closed loop at those speeds.

It depends a bit on what your right foot is doing. If real gentle on the throttle, then it might not go closed loop because the Relief solenoid is energized and the Switching not energized.

If the pedal has a bit more aggressive, then the switching solenoid gets energized (kills air to the exhaust ports and feeds the split air pipe), then the engine goes closed loop because of no Port air being fed into the exhaust ports and being mixed with the *real* exhaust gases.

I'm under the impression that IF the afr is too lean, the ECU won't go closed loop beacause it can't trim the lean mixture to the 14.7AFR range.

More often than not I run with no airpump/acv and I go into closed loop at lower speeds much more often. How much more. Never counted.

Anyway, duing those tests at 15 and 25mph it almost does not matter. The afr if read on a wideband will be in the 15's or 16's afr when not in closed loop anyway.

Series four ACV dumps all the air at 3800rpm and sometimes earlier. Depends on the manipulation of the right pedal (TPS signal and manifold pressure).

I see what your talking about. Just rambling on. I'll look and see how low of a rpm I can go to get in closed loop. I've a car right now with no converter/acv/airpump.

Anyway, I'm done.