Above 3750 rpms doesn't open Secondary ports at light load
 

That's right, I have connected LED lights to my SSV switch and Aux motor to see when these ports open. This is part of my current experiment with port timing here: https://www.rx8club.com/series-i-tech-garage-22/experiment-changing-intake-port-settings-76447/

For those who don't know, the Secondary ports are suppose to open up above 3750 rpms along with the secondary fuel injectors. This has made most of us who are concerned about MPG to cruise below that dreadful RPM.

Well, good news! With my LED light as indicator, I did some runs to test when these ports open up:
- At high loads (speed runs), they open up at 3750 rpm or 4K rpms. The Aux ports open up above 6K rpms.
- At light loads (cruising), they open up above 5K or so.
- At deceleration from top end, the Aux ports indicators flicker so fast. This tells me that the actuators open and close almost every half a second. I'm not sure why this is so or what effects this has on the A/F.
- At deceleration from top end, the Secondary ports stay open until 4K rpm. After that, it shuts off.

So what does this mean to us? It's ok to cruise on the freeway above 4K rpms, heck even 5K rpms. The secondary ports do not open as long as the load is light, no heavy acceleration. Go cruise at 80 without staring at your fuel light :D

Oh and one more thing: You know when you turn off the ignition and you can hear something in the engine by that sounds like robot arms? I just found out that those are the Secondary and Aux ports opening and closing, maybe as part of the ECU testing those ports before shutting off. First, the secondary ports are tested open and then closed. Second, the Aux ports are tested open and then closed.

I will be connecting the Secondary switch signal to the Aux port signal. Hopefully, this would trigger the Aux ports to open at the same time Secondary ports open. I hope I won't fry anything :fingersx:

very sweet.

Nice work Xyntax!!

Yes they are also load dependent and not only rpm dependent.

I wouldn't say don't worry about mileage just because they aren't opening at light loads. Whether or not you've got 2 injectors firing or 4 at any one spot, it is only going to spray what you need. When the secondary injectors come online, the primaries decrease their duty cycle and the secondaries come on just enough that the transition was seamless. This means it is no different if they add in or if they don't and the primaries just spray a little more as rpms rise. Fuel is fuel regardless of where it came from. There are 2 things and only 2 things that determine how much fuel you are using. The first is the load you are at. the second is the rpm you are at. It has nothing to do with a port opening up or not.

Why people are scared of any 1 rpm to cross is beyond me. It doesn't work that way. It's no different than being scared of a lower rpm. There is always the same amount of fuel being used for your particular load and rpm regardless of how many injectors are spraying it.

^ Thanks RG! That's true, the higher the rpm the more fuel is used. This is universal regardless of being rotary or piston.

Any advice whether I should go for connecting Secondary switch and Aux port signal together RG? Would I fry anything? I made the mistake of plugging to the L/Y wire that goes from the SSV solenoid to the ECU. After looking at the repair manual again, I realized that they were ground wires. Weird. So, I went with the SSV switch that tells the ECU if the Secondary ports are open or not.

I posted a circuit design on here a while ago that would allow you to have complete control of those ports if you're brave enough to try it - I'm not. If you want I'll send it to you and help any way I can.

Sure, post it here so that anyone who's interested in testing this can. I'm a bit disappointed how untouched this subject is. At nopistons.com, testing and changing port timing is a very common subject. Too bad, most of those guys haven't played with the Renesis yet. I'd really like to see the experts out there do their own tests. I'm a newbie, but a very curious one :D

I would think that opening the APV and VDI earlier on a boosted motor would help with the flow. If they are tuned to flow at 8kish all open.... NA then they would need to flow that a lot earlier at 50-60% higher mass flow in a FI motor.
Could the APV and VDI be setup to open at the same time? and earlier? If the solenoid can be actuvated by a +V signal..and not interfere with the ECU...then it should work

^ It should. This is one of the reasons why I'm trying to do this coz someone here mentioned that opening the APV at boost would really help. Well, if we just hook up the SSV and APV signals together, that should be close. The APV is motorized, so a voltage signal can activate it. As for the SSV and VDI, the connectors that go to the ECU are ground connectors. The signal that you could probably activate it is in its main relay. The main relay control a bunch of other solenoids too.

BTW, PTP actually disabled VDI and got a smoother torque curve at the top end. I've done it too and didn't notice much change, except the dip at 7K rpm is gone.

Although this isn't on a Renesis, I can tell you what works good from past experience with the 13B 6 port engine. Alot of RX-7 guys like to "wire open" the auxiliary ports. Somehow they think they are getting a gain when all they are doing is losing low end power below 4K. Definitely don't leave them open full time. They open at around 3800 rpm on those engines whereas the Renesis opens them at over 6250, load dependent on both. You might want to try playing with different opening points but definitely keep them functional.

The VDI on the 89-91 RX-7's was set to open at around 5500 rpm. This is all based on port timing and intake length and those manifolds are different than the Renesis so don't think that is the spot to hit on yours. Mazda did pick the perfect spot to open it on that engine as that was the exact transition point between the tuning of the effective short runner length ad the effective long runner length. Porting however could affect which rpm it works best at as tuned lengths now change and the transition point does as well.

On the 86-88 cars, the auxiliary ports were operated by exhaust backpressure. At low oad levels, the ports would stay shut. At high load levels they'd open. This meant that although they were supposed to open around 3800 rpm, they could open later or earlier depending on load. This system was a problem because everything worked fine with the stock exhaust but not always the aftermarket. People found out that an exhaust that flowed too good could actually lead to too liitle pressure to open the auxiliary ports. Many have since figured out a way around this. The 89-91 cars use a system that is similar to the Renesis in that the auxiliary ports and the VDI have electronic solenoids going to them that open send air to them based on rpm and load.

A nice upgrade which made the cars more drivable at part throttle cruising (and how I currently have my RX-7 set up) is to use the air pump to directly open the ports and VDI at a set pressure level. This will open them at the same rpm each time regardless of load. Of course I have a mechanical air pump so I can do this easily. I have found that just because load doesn't open the ports at a certain spot doesn't mean it wouldn't work better there. I like them opening at the same exact spot every time. You may not notice anything at full throttle but there is a difference at a few spots at lower throttle settings.

Let me know what you want to use as a trigger to open and close them and the amount of time you want the pulse applied to the actuators for, and I'll post a circuit that will do that.

my SSV has been stuck open for 2 weeks now... i have learned that the ports always being open causes no drivability issues or fuel milage issues, only a CEL that lights up and stays light when the ecu tries to open the SSV and see's that its already open.

^ Which is why I will not tamper with the SSV. My plan is to use the SSV signal to trigger the APV. That way at loads when the SSV should open, APV will come on too.

BTW, I reconnected the VDI back and airflow up top could barely get above 213 gm/sec. With them off, I had 223 - 230 gm/sec with pulsating readings. I don't know if it's the VDI or just difference in weather conditions, because back in February I had airflows up to 223 straight up.

^^cooler air...more mass flow in Feb :)

Hmm, so when I go to get my dyno tune this week, do you think it would be a good idea to disconnect the VDI system then?

^ Try it with VDI on and off. That would be interesting.

Check this out: http://store.summitracing.com/partde...5&autoview=sku

I found out about that product from reading RX7club threads. Any 7 driver here that has something like this?

I understand that the APV may be destroyed if voltage is applied more than 3 seconds. I wonder how the computer keeps it open then. My LED indicator shows that voltage is supplied the entire time the APV is opened.

Some types of valves will have opening and closing voltages ...haven't checked the valves on the 8.....I'll look in the shop man and see if I see anything about how they work

^ Page 104 of the repair manual (engine specs) gives a table that goes like this:

[Terminal] [Gear Rotation]
[B] [D]
[B+] [GND] [Clockwise]
[GND] [B+] [Counterclockwise]

For years when the secondaries opened it was almost unnoticible. Lately though I am getting a distinct hesitation at opening, most noticible in 1st and 2nd. Any reason for this development? Does it indicate something failing?

Well good on you for not starting a new thread.

Could be this ... check this thread out

https://www.rx8club.com/showthread.p...ight=SSV+Video

Yeah that's possible. I was getting a significant idle fluctuation anytime I lifted the clutch and idled in neutral. Then I got the cel for the ssv a couple months back. Took it to the shop and they confirmed the valve stuck open and replaced the solenoid. There was no difference following the repair except that my idling when in neutral stopped surging. It just seems that there is a much more defined "jolt" or pause in acceleration now which was not present before or immediately following the ssv solenoid replacement.

7 year necro-bump... I'm impressed.

But under a thread that even I have learned a few new things from. Heck, in 2005 I was still driving an FD on my Playstation, let alone a real car.

It's better that he bumped this thread, rather than making a new one, given those two options.