Single EBC shared over Precontrol and Wastegate actuators
 

Regarding attached image and the linked thread

https://www.rx7club.com/3rd-generati...lation-836617/

Has anyone had any luck with a single EBC controlling both the precontrol and wastegate air lines?

I just bought a HKS EVC5 with is meant to be a stepper motor EBC. The plan was to run a fresh engine in on the base pressure of the factory actuators and then slowly win it up about 1.5psi every month or so as I got the engine mapped out.

I have a PRofec B Spec-II controlling both and it works fine.

Do a search on here for "EBC Version 2". This is the setup I use and many others use for a single stepper type EBC--works great. When you see how it is hooked up, be very careful to cap the "other" side of the wastegates. No cap (or cap blowin off,etc.) = full boost which may equal blown engine! I actually welded mine closed when I had them out for other repairs.

I know there are lots and lots of FD's running around with 1 boost controller controlling 2 different actuators (wastegate valve and precontrol valve). Lots of those owners feel that the boost control is fine. The stock system has two separate solenoids for a reason however. When you are asking one solenoid/stepper motor to control two independent devices you are making compromises when you do it that way.

On the stock system, with stock ECU or Power FC, the wastegate is forced shut by running max duty cycle until the transition point takes place. Without a separate solenoid for the wastegate, you can't do that, so your wastegate can bleed exhaust away.

After the turbo transition point, on a stock system the precontrol valve is forced open by running 0% duty. Without a separate solenoid for the precontrol, you can't do that. So your precontrol valve could be partially open, causing a restriction in the exhaust manifold.

The precontrol and wastegate operate under two different conditions and are run more optimally with different duty cycle and gain parameters. Without separate solenoids you don't have that flexibility.

I can't provide scientifically quantified data showing the drawbacks of having one solenoid control two different valves but you should at least be aware of that. That's why some people run say two MBC's, or I personally prefer to have the ECU control the actuators separately (whether it's a PFC or some other ECU). If you have a Haltech with two PWM outputs, or any system with PWM outputs, you can control them independently and coordinate them with the turbo transition. If you need any help with how you could configure that let me know.

^^ Agree with Arghx. I've measured the duty cycle of the stock ECU's wastegate and precontrol outputs, and the ECU is trying to keep the wastegate closed at low RPM, varying the duty cycle of the prespool output to control boost pressure and prepare for the secondary transition. I'm not sure how you could replicate this with manual boost controllers.
I configured the AEM EMS in my car to mimic the stock ECU prespool and wastegate control methods (independent duty cycle maps for each output, reacting to measured boost pressure in attempts to reach desired boost), and the secondary transition is pretty smooth.

No promises, but if I have an opportunity to test a fixed duty cycle on both solenoids I will try to post the results here.

I've been running "version 2" with greddy profec B boost controller & apexi power fc. Lately I've noticed a problem with boost coming back after tranistion and letting off throttle. Getting back into throttle my boost does not go above 5 psi, so I am running primary turbo only. I've tested a lot of my solenoids over the weekend and have found that my charge control was trash, and my charge relief was slow leaking. If replacing those with new don't fix my issue I'll try ebc "version 1".

ARGX, is your post suggesting that if you have a power fc, you should not use an EBC at all?

I have another solution.

Use a upgraded pressure actuator on the wastegate, and leave the pre control as standard and set the EBC a few psi above the base spring pressure of the upgraded wastegate actuator.

During primary the system will be using the correct duty to regulate the boost using the pre control and the wastegate will be more shut than the pre control because it has a higher base pressure.

Then post transition the duty will be lower because the boost will be regulated by the higher spring pressure of the wastegate actuator, so the pre control should get more psi than it would with the precontrol and wastegate having the same psi diaphragms.

Obviously not good as 2 independent controllers but it should work better than a 'balanced system' I think.

Jobro's idea is interesting and warrants more investigation.

You can also use the 'transition' signal to switch one EBC between two different solenoids: one for pre control and the other for the wastegate. I used the Profec Lo boost setting for the primary and automatically switch it over to the high boost setting for post transition/wastegate. I've also used fixed pill/boost for the primary only with the ebc on wastegate, which actually works very well and is simple.

I am suggesting we expand our minds about boost control and think about it as a system. In the boost control system there is the hardware, the hoses and solenoids and actuators (plus the turbo itself). There is the software - the logic used to control the hardware. Then there is the tuning - these are the actual values put inside some table or setting.

The Power FC is already a type of EBC. All an EBC does is send a duty signal to a solenoid (or in some cases a stepper motor) according to some control logic and tuning. You can have the Power FC control the precontrol and not the wastegate. You can have the Power FC control the wastegate and not the precontrol. You can have the Power FC control nothing. You can use a stock solenoid with a restricter pill. You can use a 3 port solenoid, the same type of solenoid you would find in most external controllers. You can use a 4 port solenoid. You can use whatever combination of solenoids you want, if you can make it work. You can use 1 MBC and a Power FC. You can use an external EBC and the Power FC.

One thing the Power FC does that an external MBC or EBC does not do, is directly coordinate the precontrol and wastegate with the turbocharger transition. That is the point I am trying to make. However if you have an AEM EMS, or a Haltech. You just have to know how the system works. I have offered suggestions in the past and I don't mind answering questions on how to do this. It is at most just a few dumb lookup tables and some settings--nowhere near as complicated as the model-based stuff modern cars use for boost control.

You can't replicate such a thing with manual boost controllers, but at least you have independent control over the two valves. Any information you could share about your setup would be great (AEM EMS files, datalogs, screenshots of maps, etc).

I'm not sure where I remember reading it but someone/somewhere on this board make a strong case to use an EBC, which is why I installed one to begin with (not just for fun). But after reading what you're saying I'm not sure I understand why you wouldn't want the power fc controlling boost.
I can revert back (power fc controlling boost) pretty easily as I still have the solenoids / wiring in tact. I don't think I have the restrictor pills anymore.

Reasons to run Power FC boost control:

1) it's already built into an ECU lots of cars are running
2) it coordinates control of the precontrol and wastegate with the sequential turbo transition, and is integrated with an overboost fuel cut
3) it allows you to record duty cycle if you have a Datalogit, making your logging more powerful
4) it can be controlled externally with the PFC Commander without using a laptop/Datalogit

Reasons to NOT run Power FC boost control

1) limited flexibility in tuning it. You have two settings to change (boost setting and duty setting), with separate ones for precontrol and wastegate. They are not intuitive to tune but you can play around with them and figure it out.
2) no gear based control or other such advanced features
3) it may be difficult to control with the stock solenoids + restricter pills, although you can switch solenoids
4) There's still some general confusion about how the PFC controls boost. Until a few years ago, nobody really understood how the PFC boost control worked. The Power FC manual from Apex'i wasn't clear. I did a bunch of testing and have extensively documented in other threads how to use a datalogit to understand your turbo transition, your wastegate, and your precontrol valve.

I would personally recommend switching to 3 port solenoids rather than stock solenoid + pill, unless your car has only very basic modifications. Look online for the MAC boost control solenoid, which is the same as the AEM and Haltech solenoids.

When someone tells you to run an EBC on an engine with sequential twins, the root cause of it is a mismatch between the stock solenoids & restricter pills with the rest of the hardware (intake and exhaust restriction for example). The PFC and stock ECU are just solenoid drivers with basic feedback. They don't know what's hardware is hooked up to the engine.

arghx perhaps you can answer my question. I am running a single MBC on a PFC ECU. I've placed the MBC on what I believed to be the primary turbo wastegate actuator. The secondary hose does not have a pill. I have noticed that my boost pattern is 5-10-10. Does this mean that I have instead placed my MBC on the secondary? I used the thread on running two MBC's and I am certain I have it installed correctly. I do have another MBC, but was told I only really needed one to control boost with the PFC. Do I need to run the other MBC because I do not have a pill in the other hose? Do you happen to have a better diagram than the one posted on that particular thread? (My solution to a perfect boost pattern was the name of the thread I believe). Thanks in advance!

maybe you put the MBC on the wrong actuator, or maybe you have some other leak going on. It's hard to say.

This is one of the setups I recommend to most people running sequential twins and Power FC, explained in this thread https://www.rx7club.com/3rd-generati...tegies-874031/

You will be running two 3-port solenoids with no pills, the same solenoids you would find in an AEM boost controller, but they are controlled by the Power FC. They are replacements for the stock 2 port solenoid + pill.

I'd guess you put the controller on the wrong actuator. I run them on the waste gate ONLY and have so for many many years without any issues. If I need to restrict one or the other, I will. Then go tuning happens with the ebc settings and the sequential settings in the pfc.

Or as Raymond suggested, you may have a leak or an issue somewhere else in the system.

-J

Hmmmm. I'll put the other one on and see if anything changes. Thanks!