Twins80s

iTrader: (3)

Well I am currently putting some of my emission stuff on my car as the last owner took them all off and I cant pass emissions. I was curious if there is away to set it up so it is always blowing into the cat. I know this might sound odd but I figure getting it to pump all the time instead of off and on would be easier as I am using junkyard parts.

NoDOHC

From looking at the FSM, it appears to me that without vacuum on the control line to the air control valve, the air pump will pump into the catalytic converter all the time. I can check this for you when I get home.

RotaryResurrection

iTrader: (8)

Don't run an ACV, simply run the outlet of the air pump right to the cat. You can use metal plumbing **** from lowe's if you need an extra length of pipe, and use thick rubber hose with clamps to join them.

stylEmon

iTrader: (2)

funny, we were talking about this today. wouldnt the back pressure from the exhaust negate the effect of the weak air pump?

If I'm not mistaken, the Air Control Valve acts as a check valve so the back pressure wont effect the air coming in the cat from the air pump...

NoDOHC

The stock air pump makes 1.7 psi at idle, while the exhaust makes about 2.1 psi at redline and 1.6 psi at 3500 or so (stock components). I think that the air pump can keep up with that, but doesn't the air pump do other things too?

If this is an S5 then the VDI and aux. ports will need the air pump to make pressure, which it may not without the ACV.

The exhaust backpressure may still be enough to operate these devices (if the exhaust is stock, which I doubt).

HAILERS

Blockoff the outlet pipe on the bottom of the ACV. Thats the large nipple that should have a large hose on it leading to the right front fender.

Then the airpump air has no option other than to feed air to the exhaust ports and incidently to the split air pipe. Split air pipe normally does not much of anything in life. You want the air to go the exhaust ports prior to the catalytic converter.

Just buy a cheap CATCO converter online. They sell for only a C note plus change. No need for trickery.

Twins80s

iTrader: (3)

Ok I have installed the RB header and a bonez high flow cat which were bought from rx7.com.

RotaryResurrection I cant belive I didnt think of that! I even looked at how the air pump is on my dads z28 and it is the same way.

Thanks for all the help guys!

RotaryResurrection

iTrader: (8)

There is a check valve installed on the end of the SAP on all FC's in stock form that prevents exhaust at the cat from pushing back through the acv/airpump.

The checkvalve in teh ACV is to keep exhaust pressure from the exhaust ports from pushing back through.

RotaryResurrection

iTrader: (8)

As far as the cat life and passing emissions, either entry point for airpump air would probably be fine. The air injection at the exhaust ports is more for afterburn control than emissions/cat life. It does make sense to inject it at the exhaust ports/manifold, BUT it also requires that he reinstall an ACV to make that happen, which defeats the simplicity he is after.

Twins80s

iTrader: (3)

Well I already have the ACV installed. the only thing it looks like I am missing is something that controles the other things next to where the air pump feeds into

RETed

Easiest way to do this is...

You see that one-way, "butterfly" check valve?
Flip it backwards.


-Ted

RETed

This doesn't really matter.
The ACV redirects the air pump supply of air to bypass completely around 3,000RPM.
There's no reason to be injecting air into the cat at higher RPM's.


-Ted

phoenix7

I read a thread a while back about the corvette electric pump. Hook it up to a switch and you have have it blowing all the time or off?

HAILERS

Too rich a fuel mixture reaching the catalytic converter dooms it to a short life span i.e. clogging.

The purpose of the ACV is to.........prevent too rich a fuel mixture reaching the converter by mixing fresh air in the EXHAUST PORTS prior to the converter.

A common mixute coming out of a RX at idle is in the 13afr range i.e. a rich mixture. That is with no mixing of airpump air with it. Once the airpump is working, that afr is in the range of 15-16afr.

The airpump air is not injected in the exhaust ports when driving at a cruise speed, because the engine is in closed loop mode for the 02 sensor resulting in a 14.7 afr range.

Step on the pedal at cruise and the *switching* action is taken within the ACV and air is injected in the exaust ports again. There's several variations with the switching action in in the ACV.

Ever notice WHERE the air tube is on that converter? Take a look in case you forgot. Ain't prior to the exhaust air entering the catalytic converter. Here's hoping you did'nt spend more than a C note on that converter and are'nt going to leave it on the car for more than the time it takes to get inspected.

Think about this just for a half second or so. Your being told that MAZDA eng were such block heads, that they didn't realize that all they had to do was run a straight tube from the airpump to the catalytci converter.

So? What was it. They had brothers in law that made ACV and they thought they'd just throw some business their way? Or had stock in the big ACV company? Yeah. A consiracy.

RotaryResurrection

iTrader: (8)

Hailers, you sound like one of the purists who "restore" cars back to bone stock, "the way mazda intended" way back in 1988 or whatever, and think that any modification from stock is blasphemy. At this point in the car's life, who really cares? It doesnt matter "how mazda intended" the emissions system to work, bottom line, just do what you have to do and make the car pass, and leave the armchair engineering lectures to the newer platforms where it really matters. No matter what you do, the rotary in the FC is not going to run "clean" compared to modern standards, nor is the fuel economy going to improve.

HAILERS

Run the airpump straight to the side of the cat will burn the sucker up. Common knowledge. You trying to convince people that there are no consequences to doing that and that is bullshit.

There's a reason the airpump air enters the exaust ports prior to the catalytic converter. Wake up and get your head out of yiour dark spot.

And another thing. The ACV is held on with but three nuts/studs. Now how difficult would it be to do the job the RIGHT way and have the system work and not FAIL like your telling people to do? You have to be pretty simple not to be able to reinstall the ACV and get it woking right. Just read the FSM.

RotaryResurrection

iTrader: (8)

I will say it again. I'll even bold it for those who are reading comprehension challenged. There is a check valve present in the split air pipe for all FC's that prevents exhaust pressure from running back into the airpump and causing damage.

Care to explain exactly how a purely mechanical, belt driven air pump can be damaged by exhaust gases that can't reach it to begin with? Or perhaps you believe (mistakenly) that the ACV presents some sort of necessary restriction that keeps the airpump from "tearing up". Common knowledge that the airpump will "burn up" huh? Please, show me the source of this common knowledge. In fact, I'd love to hear from all these owners of airpumps that have burned up due to improper air exhaust routing.

Bottom line, unless you let water or a foreign object get inside, the airpump is BULLETPROOF. It produces X amount of air at Y rpm and nothing can change that. What you do with that air is a doesn't make a rat's ***...vent it back to atmosphere, send it to the exhaust ports, send it to the cat, try to use it for a supercharger, hell you could even plumb it inside the car and have a blow up doll for a passenger, it doesn't matter, that air pump is not going to tear up.

stylEmon

iTrader: (2)

i think he was saying the cat will burn up faster if you route air directly to it.

My reason for not using the acv is because i dont have one... and i really need to pass emissions NOW!!

I ran her through yesterday with just a cat, and charcoal canister. (failed) I have an air pump bolted on, but not hooked up. I wonder what difference it would make in the test if I ran the air straight to the cat...?


I was double the limit on HC and CO. But passed all other areas...

hhn2002

well im no expert of emissions but from what i know oxygen is needed to burn off the rest of the HC and also to jump start the conversion of CO to CO2. to the point: you need more oxygen(dont we all) in ur exhaust. at the very least routing the airpump directly into ur cat will at the very least help considerably but will it be enough, i cant say for sure. you can certainly try though.although for the most optimal effect reinstallation of the acv is the only option i fear.

RotaryResurrection

iTrader: (8)

He may have been saying that, but it is *common knowledge* that the opposite is in fact true.

Airpump air is injected into the cat to keep it cooler and extend its life under the intensity of the rotary exhaust, not so much to impact AFRs entering the cat.

AUGieDogie

iTrader: (4)

I solve the problem by only running my cat for about two days. One day befor the emmisons check, then one day after. Then back on goes the RB presilencer and into storage goes the cat, at least till i do my other car

As far as doing it the right way. What is missing from your car? The ACV does most of the hardwork of routing the air, but it is a RPITA. Going from memory there are 3 hoses and 2 solonoids (sp?) on the ACV. The hoses all come from the drivers side and are controled by the little black, solinoids with colored dots on them. The to electric connectors control ones on the ACV.

You need a working check (buterfly) valve in the ACV, as well as one on the cat supply valve. Appley vacuume to the "pots" on the ACV and make sure they they move and hold a decent vacuume. apply voltage and ground to the two sets of connectors to make sure they both click. OH and make sure your Air Pump is acctually pumping air.

Good call with the bonz cat, I love mine. I don't really even notice a difference between performance with it on versus the pre silencer.

Good luck.

HAILERS

No. The air is injected at certain times into the split air pipe, not all the time, for oxidation of the exhaust gas in the rear *brick*. The air is cutoff to the split air pipe over approx 3800rpm and not injected to the split air pipe at all during Idle.

Drive the car on the hwy for over a couple of minutes and the relief valve opens and the airpump air is dumped into the fender silencer. In other words not to the port air nor the split air pipe. Rekon there's a REASON they do that? Yes.

staticguitar313

iTrader: (2)

Food for thought:
I had a Bonez cat in my stock 86 GXL, car runs great, i turned it into chunks and dust, rear section of the catalyst desintegrated . . . .

HAILERS

There's a thing called the LIGHT- OFF TEMPERATURE for the catalyst. Until the catalyst reached that temperature it is inefficient.

Pumping fresh air continuously into the oxidizing section of the cat is counter productive. The hydrocarbons won't be oxidized (burnt). They'll eventually clog that sucker up.

That's most likely why there is no continuous supply of air to the oxidizing section of the catalytic converter. Counter productive. Senseless.

If your going to run air directly to it, then get the thing inspected right away and then remove it so it can be used again. Or leave it on and waste your dough.

EDIT: And while here, do a little looking on the Web and you'll find that the catalytic converter work best at approx stoichiometric afr values. Again, that's why we have Port air being injected in the exhaust ports at idle. Not as important(Port air) at cruise because the ECU is operating in closed loop with the 02 sensor which reuslts in afr close to stoichiometric.

RotaryResurrection

iTrader: (8)

Keeping a convertor up to operating temp with a rotary engine in front of it is never an issue. EGT temps generally rise as AFR increases, btw, so as the car runs closer to stoich on the highway, the cat runs hotter and works more efficiently, this is not the issue at all. The issue is keeping it cool enough from melting over a long period of time. In the short term, it can likely do without the air pump altogether if it is nice and hot for the test. If it sits in the parking lot for 30 minutes before being idle tested of course it is not going to work.

Next you're going to give a lecture on the benefits of fuel pulsation damper versus banjo bolt, I suppose? Save us the trouble.