Consume Glue

I've searched this site for hours and just can't seem to find what I'm looking for. I really want to clean up the amount of things on my engine and have as few vacuum lines as possible. If the ACV just chooses where to divert air from the air pump, (either to the cat or the VDI and 5/6th ports) why can't I just bypass the ACV altogether and "T" off the air pump straight to the VDI and 5/6th ports solenoids? As far as I understand, the ports and VDI are actuated at certain RPM by the ECU, so the ACV is really just the middle man. Does the ACV constantly supply them with pressure or only at those certain RPM and that's why you need the ACV?

If I can "T" off the air pump and run directly to the VDI and port actuators, do I need to have a bleed valve to ensure there is not too much pressure going to them?
I've read a lot about this but I haven't seen anyone do what I'm asking. It could also be because I don't understand how the whole system works.

j9fd3s

iTrader: (3)

if you look at the ACV there is a little vacuum (i guess its technically pressure) hose right on the inlet, and that is the hose that goes to the solenoids.

there isn't a lot of air flow to the solenoids, its mostly just pressure, the air flow goes to the ACV.

i've always thought it was simpler to leave it alone, but ymmv

Consume Glue

Right, so if that is what goes to the solenoids, then why couldn't I just delete the ACV and connect right to that hose straight from the air pump? I just don't see a need for the ACV if I can run a pressurize line from the air pump straight to those solenoids and bypass the ACV altogether. Unless the ACV actually controls when air is supplied to those solenoids, I see absolutely no use in keeping it considering that i have no cats.

professionalpyroman

This might not be the answer you like, but Mazda didn't put extra vacuum equipment in your engine bay. Especially on the S5 NA, you need all that stuff, including the vacuum routing and solenoids. There was a new Rx7 owner that I helped last year because he did just what you are suggesting, and sold off all the vacuum stuff and wondered why it ran like garbage. He ended up having to buy back all the items he sold off for more than he sold them for in the first place.

The vacuum systems of rotaries are more complex than that of your typical piston engine. This is partially due to the wide range of airflow that each intake has to accommodate compared to that encountered in a typical piston engine. Here are a few examples of vacuum systems you will encounter on your S5 NA engine, what they do, and why they are important. When I say vacuum systems, I am just talking about air controlled circuits regardless of operating pressures/vacuum.

On your NA, you will have about 6 different systems that your vacuum system is using to mechanically control your intake of air. They are:
1. 2x Emissions solenoids (ACV) Distributes positive air pressure to 6-port actuators, and to Split Air solenoid for Catalytic Converter
2. Fuel Pressure regulator
3. 6 port actuators - open at higher rpm range to supply more airflow into engine (turbo engines have a compressor shoving air in instead)
4. VDI - acts similar to long tube runners, allowing better performance by opening up at high rpm, and using short runner lengths at low rpm
5. PCV - removes vapors from crank case, gas tank, and burns them in the engine
6. Air bleeds (includes air supply for oil injectors) - Bypass air around throttle body to maintain airflow around fuel injectors. By eliminating these, you cause a number of issues including: fuel wetting on intake runners since atomized fuel is not being adequately mixed into air stream, improper airflow into engine causing bogging under idle, and if you readjust the throttle body to account for eliminating these, your initial throttle position will be errant if you are using the stock ecu. These are meant to provide not only moving air past the injectors at all times, but to provide a metered amount of air when the throttle valves are closed.

If you are wanting to tidy up the engine bay, one way is to get a silicone vacuum hose kit and replace the old crusty hoses. If you order extra lengths of it, you can tuck and clip them around so they don't stick out all over the place. Mazda did their best to try to pack these systems in as compact manner as the times allowed. This was a brief overview of the systems, hopefully it increased your understanding of them. I'd encourage you to spend some more time looking at the systems and trying to see where they fit in the bigger picture. Best of luck, let us know what other questions you have!

Consume Glue

I understand this, and I know that I cant just delete everything. I actually planned on keeping all of that stuff and deleting everything, I just figured that I might be able to delete the acv but if it's not reasonable to do so then I wont, it was just an idea I guess.

I bought a ton of vacuum hose and zip ties to make sure everything is new and on tight, I will be rerouting it all for cleanliness. I just dont want all those metal lines there so i will be running all soft lines, and I want to get rid of as much as possible and only keep the essentials like you listed. I appreciate your help.

professionalpyroman

Is it a matter of looking at rusty metal lines? You can sandblast and paint or electro plate them if you want them to look nice. You can even color code them.

At some point, Mazda decided to have someone design those metal lines to more effectively organize the vacuum system and other plumbing. Then they made bent and welded rigid lines which cost way more than rubber hoses to produce. There was probably a reason they went with the more expensive solution. If you eliminate the metal lines, you may have a spaghetti mess on your hands.

Consume Glue

For me it's more so a matter of trying to eliminate as many points for vacuum leak as possible since I have done leak tests before and it isnt even holding pressure.

NCross

iTrader: (18)

The hoses that "blow" for the actuators will not cause a vacuum leak. The split air pipe for the cat will not cause a vacuum leak. The hoses that "pull" (vacuum) to pull on the diaphragms for the solenoids on the ACV can cause a vacuum leak, as well as the gasket itself. Those two hoses come off of the top of the ACV and route to the blue and gray solenoids on the rack for switch and relief. One tip I'll give you is to unplug the blue solenoid, if idle drops and smooth out a bit suspect an internal problem with the ACV.

I have actually taken the acv off and reinstalled it with a block off plate and 2nd gasket to eliminate all ACV function except port activation.

Consume Glue

Can someone confirms this works????? I want to do this now!

NCross

iTrader: (18)

It will be just like you put a block off plate on an earlier 12a/13b except your auxiliary ports and VDEI will still work (as long as you run vacuum lines to the correct places). You do this when you suspect an internal failure of the ACV. I have this setup on one of my series 5 cars right now due to a torn internal diaphragm for port air relief causing an internal vacuum leak. Auxiliary ports and VDEI are still functioning.