Long-term testing with Power FC single turbo boost control
 

I've discussed my Power FC single turbo boost control setup in various threads and sections of this forum. I thought I'd start a fresh thread to discuss my long term observations after having used this setup for almost a year now. For those of you who aren't familiar with my setup, here it is in a nutshell:

PFC Single Turbo Boost Control Setup/Installation

1. Hook up a boost control solenoid to the factory wastegate solenoid plug (FD) or directly to PFC pin 4U (FC). You have a lot of solenoid options as long as you know how to hook up the plumbing. You can use the Apexi/Denso solenoid which is expensive. You can use an AEM/MAC solenoid. You could probably use a GM, Perrin, etc solenoid as long as the impedence isn't too different from the factory solenoid. Speaking of which, you can use a factory 2 port solenoid on external wastegates (I am doing that right now).

2. Run the plumbing. If it is a 3 port solenoid, just hook it up like any typical external boost controller would call for--usually with the solenoid connected to the top port on an external gate. You can also use the NO (normally open) port on a 3 port solenoid for an internally gated turbo, including FD twins/BNR turbos or FC stock/hybrid turbos. A two port solenoid can be used on an external gate as long as you have a bleeder installed in-line to relieve pressure, which I won't get into at this point. A two-port can also be used on an internal gate if it is hooked up in a bleed fashion, tee'd off like the factory 2nd gen solenoid or after the wastegate like on the FD.

3. Get a Datalogit and make the setting changes depicted on the right:

https://www.rx7club.com/attachment.p...1&d=1271741167

To make a long story short, you are tricking the PFC into thinking it's controlling boost on sequential twins (something it already does pretty well). That's all I'm going to say about that for now. The settings on the left are for tuning the boost levels.

Tuning the Controller

After initial set up, the Commander can be used for tuning although a Datalogit is useful. You've got two possible boost selections: option 1 and option 2, both of which can be selected and tuned with a Commander. You can make one your high boost and the other your low boost or cold weather option. The primary and secondary values are for sequential twins only: you should make them the same values.

To tune it you use the "boost" setting as a coarse boost adjustment and the "duty" setting as a fine adjustment. And by that I mean the "boost" setting kind of puts you in the ballpark (as long as "duty" isn't too low) and the "duty" setting then gives you smaller adjustments. These are all kind of "ballpark" values. You just fiddle with them until they work, keeping in mind that the PFC will engage a fuel cut if the boost level is around .25 kg/cm^2 higher than the target. You may have boost that consistently measures higher than the target you set. That's ok; the key is keeping boost stable and consistent.

I've got a T04R with a Tial 44mm external gate (13psi spring) using the factory FD 2 port solenoid. I started out with conservative settings. I set target boost to .90 kg/cm^2 (right around what my spring pressure is) and 20% duty. This caused boost oscillations and confused the PFC. Let me list some of the combinations I have tried over the past year.

.90 boost 20% duty underboosting and oscillating
.90 boost 40% duty
.95 boost 42% duty steady at about 15psi in most weather
.95 boost 46% duty steady at about 15.5psi in most weather
1.00 boost 46% duty almost 16psi in most weather
1.00 boost 50% duty about 16psi in most weather
1.05 boost 52% duty about 16.5psi in most weather, a little bit of oscillation
1.05 boost 50% duty about 16.5psi in most weather, more stable, slight differences depending on gear

Here is a log with the settings 1.05 boost 52% duty:

https://www.rx7club.com/attachment.p...1&d=1271886591

"PIM" is actually manifold pressure, where 10000 = 0psi and 22000 = 17psi . WG% is the logged solenoid duty cycle where 255 = 100%. This is a 1st and 2nd gear pull on the street, 1/2 throttle in 1st and WOT in 2nd. You can see that the duty is flat at first. That's the PFC holding the gate shut to improve spool (similar to your "Start Boost" setting on a Profec Spec II or "Spring" on an AEM Tru Boost). Then the gate opens and duty drops down, while the PFC tries to keep boost stable by varying the duty. You can see the boost is pretty steady there in 2nd gear as I go WOT, but I did end up dropping the duty setting by 2% to reduce fluctuations. This is not a turbo setup designed for low end and spool. In third gear the boost rises slightly over what is depicted here.

Conclusion

What I've figured out over the past year is that

1. PFC boost control works, you don't need to buy the kit, you just need someone to make those sequential turbo settings changes in your map with a Datalogit

2. The boost and duty settings are "ballpark" values. You just have to fiddle with them until the boost is relatively steady, being mindful to set target boost high enough that you're not easily tripping fuel cut in higher gears. Fuel cut is a way to protect your motor should your wastegate fail, but I would still try to avoid hitting it.

3. Boost will rise when it's cold outside--the PFC can't completely stop this but few boost controllers are smart enough to do that. You can manually lower the boost and duty settings to correct this or just have one of your boost options be for cool weather.

4. The Datalogit is a powerful way to improve your boost control tuning, but I wouldn't consider it necessary for tuning boost. I have made plenty of adjustments with the Commander only, just by using the up key in monitor mode for peak/hold display. You can also look at a separate boost gauge.

5. Keep in mind that the default calibration for the stock FD MAP sensor tends to read the boost as a little low, perhaps 1psi too low depending on boost level, altitude, etc. The log above was taken using a calibrated GM 3 bar sensor.

Hope this helps.

I have been using the MAC valve to control the external WG on FD with T04E and thus far the valve is inconsistent. There are times that the valve will work great and times that it won't work well at all. The MAC valve may be getting stuck. Perhaps it is not taking the heat very well. Again, I suspect that the issue is in the MAC valve and not in the PFC control system. The flaw in using the PFC is the lack of gear dependent vent duty. I see very different boost peak readings between 5th gear (highway) and 2nd gear (autox) at a given vent duty. 64% will keep 5th gear at 1 k/m2. The vent needs to be raised to 86% to reach 1 k/m2 in 2nd gear (keep in mind the 2nd gear load is reduced because I have 4.77 gears).

how do you have it hooked up? is it going to the top port of the gate? I actually have a dedicated hose to the side port of the gate and then the solenoid runs to the top port. I don't tee them off one source.

Some Datalogit logs would help determine what exactly is going on. Looking at rpm, boost, and solenoid duty can tell you a lot. I've been under the impression that these are fairly reliable solenoids. I haven't seen one screw up on the AEM Tru Boost for example.

The lack of gear-based control is certainly a limitation, but it's a limitation found on most aftermarket EBC's anyway. To get gear-based you need to buy an AVCR (there may be some other obscure external ebc that can do it) or use an ECU that has gear-based maps. On my car I have a difference of .75psi at most between the peak boost levels in 2nd through 5th gear. This is acceptable to me.

Please ignore this issue. The BOV venting made the MAC valve wires rub against some other items in the engine bay and wore right through. Fixed. The gear dependent peak boost variation is still prevalent.

If possible post some Datalogit logs that illustrate the variation

I don't have a logger.

WIth a Datalogit you can log the actual wastegate duty cycle curve (see image in 1st post) and you can change the rpm at which the wastegate opens in the settings 1 tab of the software. It's a lot easier to tune.

on my previous car a s13 with sr and t04e and tial 44mm wg. i setup the pfc to control boost using an apexi/greddy solenoid. it worked better than any previous separate controller. no fiddling it just worked and held boost consistently. i differ from you guys though. i dont like using the top port, if the wg spring is strong enough its not necessary imho

damn, i thought you were dead? ^^

i did have death threats on my life. none came through though

thanks for the info. i'm going to be trying this today/tomorrow.... i'll report back how it goes!

What car do you have now?

an fd with pfc and greddy solenoid

thank for the info arghx. it works perfectly only weird that happened to me was. i used my datalogit to change the turbo transition and then enable twin turbo control but twin turbo control didn't actually turn on for some reason. i just had to enable it in the commander while i was driving.

glad it's working out for you. you are using a Greddy solenoid, so that plugged right into the factory harness right?

yes... should have been plug and play. i got it free so i had to replace the connector on it back to stock. someone had already hacked it up. so i fixed it to make it plug and play

yeah the Greddy, Apex'i, and HKS (only HKS EVC-S) solenoid all plug into the factory harness because they use the same AMP Econoseal connector as the factory precontrol and wastegate solenoids.

the car is going to get retuned for more boost and i'll report back how it goes but i already know it was awesome in my old car. i'm sure i will be happy again

are you still using the oem solenoid ?

^ yeah I am. no problems for the past year and a half

i thought about trying it but i just don't trust it... that is awesome to know it works though

raised the boost to a little over 17 pounds. current settings are 1.10 boost 56% duty

i've been fixing lots of other issues. have not had a chance to retune with more boost on my car... fun stuff

Hey Jon, I am surprise that the car is still twins, by now I thought u setting it up for big single or not yet?
Khris

when did i ever say the car has twins....

my fault dude i read this from above (i used my datalogit to change the turbo transition and then enable twin turbo control but twin turbo control didn't actually turn on for some reason) and i thought u were twin.