I always thougth that the boost value is actually for the fuel cut and the duty is what actually controls boost; is this not true?

What happens if you leave your duty unchanged but increase the boost value?

IIRC Fuel cut happens when your actual boost > Set Boost Level + 0.1 kg/cm^2. Duty is what controls boost.

tuned my car last night. pfc was able to control boost up to 1.2kg. worked pretty damn well

Generally speaking it will go up but the best way to know is to log wastegate duty cycle and boost to see what happens. You've just got to play with it a little bit like any other kind of tuning. It's not really that complicated.

Technically it's supposed to be .25 kg/cm^2 higher than the set value, but I've seen it kick in lower or higher than that at times. There has to be some other calculation being performed behind the scenes that affects it. I think there might be a delay timer or other logic based on the rate of change of boost. Subaru for example uses a delay timer for overboost fuel cut on their factory ECU. Boost has to exceed a particular value for a particular amount of time.

On the PFC I have tried many combinations of different settings in different weather conditions. I have noticed that if there is a very very sudden spike the measured boost may exceed the target by more than .25 kg/cm^2 for a split second the fuel cut may kick in. On more sustained pulls in high gears it will kick in lower.

Anyone know which wires you would tap into on the ECU for the solenoid assuming the originally wires for the solenoid have been eliminated form the harness?

thewird

I have wired this up before. FD pin 4U is the pulsewidth modulated ground output for the wastegate solenoid and then you need a 12V power wire. FD pin 1B comes from the main relay so that's one option if you want to tap power from there. Don't tap into a 5V reference voltage wire for a sensor by mistake.

https://www.rx7club.com/attachment.p...1&d=1314494101

Awesome thanks :)

thewird

good to know that the pfc can control boost, will try this on my friends fd.

anyone has a picture of the boost control selonoid? ( I never had a chance to play with stock twin went straight to single turbo :(

http://www.mazdatrix.com/pictures/c-...-2850-N3A1.jpg

those are the stock FD 2-port boost control solenoids, if that's what you are asking. FC also has a 2 port solenoids; most turbo cars use that style, but there are some cars that come with a 3 port solenoid (like on an aftermarket controller) from the factory

Does the PFC utilize feedback at all, or is it strictly duty cycle. I am currently running the AEM Truboost and cannot get it to hold boost so I am looking at other options.
Thanks,
Dan

It utilizes feedback, but you do not have direct control over it (there is no actual "feedback" or "gain" setting). An AVC-R does, but it has a bigger learning curve and you do not have data logging integrated with your engine management system. On the AVC-R you set a target boost and a baseline duty cycle. You set a "feedback speed" which is basically a gain parameter. The AVC-R will add or subtract solenoid duty in an attempt to achieve the target boost--higher F/B speed increases this sensitivity, which means you are more likely to hold boost up top but also more likely to spike. The same idea carries over to other controllers.

The Tru Boost has only two settings: the pressure at which the wastegate is allowed to open, and a basic duty cycle. It is a dumb solenoid driver. Many other external controllers function like a Tru Boost + a gain function; a Greddy Profec Spec II and a Turbosmart are almost exactly like a Tru Boost except they have a gain option.

https://www.rx7club.com/attachment.p...1&d=1304450799

Check out my full boost controller comparison thread. https://www.rx7club.com/3rd-generation-specific-1993-2002-16/electronic-boost-controller-comparison-chart-952767/ The Tru Boost is one of the non-ebay EBC's available without feedback. I ultimately chose the PFC boost control for these reasons:

1) direct integration with engine hardware including use of the MAP sensor; lack of redundant hardware such as extra pressure sensors and boxes; integration with overboost fuel cut

2) direct integration with data logging (FC-Edit software)

3) low cost

4) ability to use the Commander to switch boost levels and monitor peak boost or quickly see the boost curve with the Commander chart display

when choosing the PFC I gave up the following:

1) boost-by-gear capability

2) the more intuitive control available with the simplest options of external controllers, like the knob-based units (Greddy Profec S)

3) direct control over feedback and wastegate opening pressure (no direct way of setting these, PFC decides indirectly based on other settings)

I'm interested in doing this to replace my Greddy Profec-B (don't like how bulky the solenoid is in the engine bay and like the datalogging/overboost protection capabilities of the PFC), but can't decide what solenoid would be best to use. Being plug and play doesn't matter to me since I am planning on rewiring my harness. Any opinions?

What is your setup?

Currently: Power FC with Datalogit and stock MAP sensor, street ported engine, T04Z (0.84 A/R) at 1kg/cm^2, 46mm Tial wastegate, 4" exhaust, HKS V-Mount
In Process: new ignition setup (IGN-1A's), water injection, rewire engine harness

http://www.ebay.com/itm/Boost-Soleno...923#vi-content this solenoid will work fine... MAC part# 35A-AAA-DDBA-1BA . It is the same as the AEM/Haltech/Grimmspeed solenoid without the markup. You can cut off the wastegate solenoid harness plug (hope you didn't "simplify" this and completely cut it out) and hardwire the new solenoid to it.

Or instead of cutting anything you can buy this plug pigtail as an adapter to put on the solenoid: http://www.bmotorsports.com/shop/pro...oducts_id/1674 then it will plug into the stock harness

Thanks, wasn't sure if the standard MAC solenoid would be good enough.

In strict terms of controlling boost, do you think that going to the PFC with the MAC solenoid will work as well as my Profec B? The OG Profec B really does work awesome, just quite bulky and doesn't have logging capabilities.

Also, what do you mean by "Hope you didn't 'simplify' this and completely cut it out"? How is this different than "cut off the wastegate solenoid harness plug and hardwire the new solenoid to it"?

If you have a working boost controller, why would you be debating switching to the powerfc? By using the powerfc to control boost, you lose the ability to have a tight fuel cut above your target boost since it will be forced to be 0.25 bar above your target boost. I have also found that boost is less similiar between pulls for some reason especially 2nd gear stuff.

thewird

The main reason I am thinking about switching is because of engine bay real estate. I am planning on installing a water injection system and a new ignition setup, so space is going to get tight. The Profec B solenoid box is quite bulky and has to be mounted so that the two vacuum ports are facing up, which really limits mounting options. Also, you have to run a vacuum line into the cabin to the back of the Profec B controller, which is less than optimal in my book. Here's a picture of how big the GReddy's solenoid box is...

http://www.floridasupras.com/attachm...yprofecb-1.jpg

I'm not dead set on doing this yet because like I said, the Profec B works great, but the smaller solenoid and additional mounting options, the capability of logging, and keeping all vacuum lines in the engine compartment sounds really nice. That's why I'm asking questions and want to be 100% positive I will be happy with my decision. The issue with boost being different in each gear is what scares me about the PFC control.

The plumbing (where you source the lines for example) and the individual characteristics of the setup (wastegate size and position) are all factors in how the PFC boost control (and any controller really) behaves. That being said, the Profec B (and Profec S) are among the simplest and most stable boost control systems out there. The Profec B uses the stepper motor as shown above. If you want something very similar to your Profec B with a smaller valve unit, just get a Profec S which uses a regular 3 port solenoid.

That really depends on what the final settings end up being. In practice they usually aren't that far apart. For example, on my own personal car my setting is 1.10 kg/cm^2 with 52% duty. My actual peak boost is usually 1.20 kg/cm^2 and fuel cut kicks in about 1.30 kg/cm^2 according to the Commander. Some people like the fact that the fuel cut will be automatically adjusted with the boost cut setting (as opposed to having to change an external boost controller and then change the fuel cut in the PFC, or eliminate the fuel cut altogether).


I can't say for sure whether you will be as happy with the PFC boost control. The Profec B (and its newer sibling, the Profec S) are basically the easiest to use controllers out there and for many people that trumps everything else. If you want the boost to behave the same way as it is now, don't switch controllers or if you do, switch to a Profec S.

I might do some experiments and try both since the cost to do so is pretty low. I already have the Profec B installed (might try and find a better mounting solution though) and it is less than $50 in parts to get the PFC boost control up and running. My gut says I will end up sticking with the Profec B though.

Also about to using the boostcontrol funtion on a S5 TII, streetport engine, BNR stage4

What would be the optimal solenoid to use? or the stock 20 year old TII solenoid, which will T in and require a restrictor of some sort to work. or a 3 port solenoid.

I have a healthy supplie to the pierburg one used mainly in VW/Audi 1.9 tdi engine with wastegate turbo. they run stock at 0.9 bar

http://www.krautwagenparts.com/images/028906283F.jpg

Or would it be better to use one with bigger hose connections, as found on newer 1.8T engines

http://imageshack.us/photo/my-images...qmokjketlk.jpg

Most people use the MAC valve which is what every aftermarket boost controller uses that doesn't use a stepper motor.

thewird

I went from a Profec S to PFC control using the greddy solenoid and have been running this way for a couple years and love it. My boost is very consistent, ive never experienced a single overboost and there is less junk inside the car. Where I live seasonal changes are very mild so Ive never even had to adjust for different seasons like some people have mentioned. I will say I never had any problems with the spec S and it was very simple and easy to use, I just prefer to keep the wires and electronic crap to a minimum inside the car.

You can make almost any solenoid with the proper voltage work. I have used an FD solenoid on an external gate. For a BNR it would be easiest to use a 3 port like the MAC valve. If you have something else, give it a shot.

Sorry I didn't get involved in this thread sooner, I remember when you were asking for some terminated wires Raymond. I figured I would update this thread with some pertinent information.

The Apexi Boost control kit uses the precontrol solenoid connection for their wastegate solenoid. What this does is allow for the sequential system to be turned off and use the "Primary" as the setting for boost level on Boost Settings 1 & 2.

Our S5 PFC Adapter has always had the Turbo Duty Solenoid (3R) going to Pre-control (4V) on the PFC for boost control and has worked very well, even with the stock solenoid.

For this same reason we have recently added the BC (boost control) wire to the 4V terminal of our S4 PFC Adapter.

I am sure that the 4U connection works, but using the 4V connection the solenoid reacts quicker and does not require the system to be tricked into thinking that the sequential system is activated. Which means there is no need to alter the transition times.

For those with the PFC in an FD just change the connection over to the precontrol and turn the sequential system off.