I've looked through the haynes and Factory service manuals, and I still cant figure it out.

I know it has to do with the emissions, but not much more than that.

I need to block it off because I'm fitting a S5 manifold on an s4 block. What are the problems with doing this? Can I still pass emissions?

 

port air does two things:

1) helps in combusting HC (unburnt fuel) past the combustion chambers

2) provides extra air to the cats for better oxidation

It is very important for emissions. You may be able to get away with it if your car is very well tuned and/or you just want to be emissions legal for a short period of time (just the cat, no air injection)

For more info on this,
check

The MAZDA RX-7 86-88 technical page

under emissions->secondary air

Hugues-

 

That's a confusing question. Both series four and series five use PORT air. The acv sends air from the air pump thru passages in the intake manifold, then thru passages in the front and rear side housings, to be mixed in the exaust Ports.

So I'm confused. Just what makes you say the port air is going to be blocked off????? Sorry but I don't have a series five to look at. Just where is this blockage happening?????

If you go to the http://www.iluvmyrx7.com you can download and look at bothe series four and series five FUEL sections and see that both use PORT air. as an emission tool.

 

Schematic of the series five acv and PORT air passages:

 

Series four acv/port air jpg:

While waiting forever for this site to accept a jpg, I thought about your problem. I think you have a misunderstanding about Port Air.

I think what is happening is your looking at the series four exaust gasket that has a one half inch hole in it that matches a hole in the exaust manifold and a hole in the *block*. That hole is for the EGR on a series four. A series five does not have an EGR valve so it does not have that hole in the manifold or the gasket.

So if you are blocking off that hole in the block, you are not blocking off PORT AIR. The PORT AIR is sent to the exaust thru the diffusers in the exaust ports. Hard to see the passages unless the diffusers are out or the rotor housings are seperated.

 

Not a chance. The port air is injected into the exhaust sleeves to help burn hydrocarbons. Without it, your emissions will go through the roof even if your car is leaned out.

I went through this when I put an S5 intake on my S4 block. My solution was to use the S4 lower intake with the S5 VDI and Dynamic chamber. This works fine except that one of the studs on the S4 lower intake does not line up with the S5 VDI. Remove the stud...

Jeff

 

Let me help:
There is a difference in the passage that the port air takes from the lower intake into the S4 and S5 blocks.

The S4 lower intake routes the port air from the ACV into holes in the end plates of the engine block.

The S5 lower intake routes the port air into one hole located in the center section of the engine block...

Jeff

 

Makes sense to me. Gotta buy a junk series five engine to play with.

 

damn damn damn!!!

so i'm going to have to use the lower intake from an s4??

I do have a lower intake manifold from a s4 lying around, but ALL the other components are s5.

What do I do about VDI? Do the vacuum hoses line up correctly?

This REALLY messes up my plans as I was going to install my manifold on tuesday!

 

On a series five the VDI and the aux ports are driven by air pump air that is sent thru a solenoid for each. The solenoid is actuated by a ground signal from the ECU. Your series four ECU does not have a output to drive these two components nor does it have the solenoids.

Both problems can be overcome with a aftermarket electronics unit from Summit Racing catalog. About fifty bucks for a unit. This http://www.summitracing.com/ Part number SUM-830449

 

yeah I did a search on this and nothing seems to match my current situation.

Perhaps its would be better if I present a senario to better illustrate what I'm talking about.

Suppose you have an s5 rx-7. The you replace the motor with the s4 BLOCK only. You also need to pass emissions, so blocking off the port air is not an option. You also have a s4 lower intake, and thats it.

what would you have to do to make the lower intake work correctly with all the s5 components?

I would assume that you would use the s4 lower intake and the s5 upper. but no example out there shows this swap done while using all s5 compnents. (ecu and everything)

Do you guys understand what I'm saying?

So what mods whould I have to do?