The duty cycle values are for spooling only. They have no effect after you are at full boost. The ECU does not control boost, the restricter pill does. Your car is no longer stock, therefore a boost controller is needed to keep stock boost levels or drill the pill as previously suggested.

thewird

I just went out to have a poke around, i was determined that my solenoids were to fault. I found that the hose from the pre-control actuator to the solenoid had popped off at the solenoid end. Now THIS can cause overboost, and in my case it was the cause. I took the car out to a nearby private road for some testing, on the way out there my boost was down at 8psi ( i lowered the duty cycles on the PFC to 30% and hadn't brought them back up)

when i got to the road i then upped the duty to 48% and this then brought my boost up to a nice 11-9-11 pattern.

So in conclusion while i do realise that a MBC is benefitial (in my case it wouldn't have made a difference as i was advised leave the pill in the PCT line and let the duty control that) i still believe it's possible to control boost with the PFC.

Weather here is awful just now, and it's not the safest testing environment but my preliminary tests are positive.

Im not trying to thread jack but my rx7 came with 3" downpipe and full exhaust and im installing a catalytic converter in the mid pipe and im wondering if this would create boost creep or will i need another one by the downpipe?

From my understanding - installation of a Cat will reduce boost creep - why are you putting in a Cat?

will you need another 'what' by the downpipe?

I'm still waiting for thewird to contribute to my last post.

another cat....sorry
I live in california and emissions are strict

Yup, good ol' Arnie.

You're going to put in a Cat, and a pre-cat?

I'm going to have to disagree with thewird about adjusting boost with the Power FC in this particular case, although he does know his stuff and I respect his input. The vehicle has few modifications and I would expect adjusting the boost control settings to help.

You can incrementally drop the "boost" and "duty" values to see if you can lower boost. Did you have the first or second option selected?

There is a low and a high boost setting built into the default map.

The low values (first option) are:

Pri .80 kg/cm^2 56% duty
Sc .70 kg/cm^2 64% duty

I would incrementally drop the target boost and the duty in alternating fashion.

So you would do something like

.80 / 50%
.70 /60%

.75 / 50%
.65 /60%

repeating a similar pattern. You're kind of fishing here. If you had a Datalogit you could log the boost and duty cycle and adjust it better from there. Whatever you do, in your situation do not raise it above the default values.

The "boost" and "duty" settings control the behavior of the solenoid valves. Think of "boost" as a sort of coarse correction, and a "duty" as more of a fine adjustment. "Pri" mostly affects the behavior of the precontrol solenoid, before the transition point that is set in the Power FC. "Sc" controls the behavior of the wastegate.

The best way to tune boost control with a Power FC is by using the Datalogit interface so that you can view charts. Here is an example... this is from a car that had some issues, but it shows what I mean. The vehicle had the stock 2 port bleeder solenoids but you can also substitute in 3 port solenoids like what you would find with a separate aftermarket controller:

https://www.rx7club.com/attachment.p...1&d=1341278206

On the right you can see the boost and duty settings that you would find in the Commander. Here I was raising them up in order to reduce boost drop off in this vehicle... later it turns out that the turbos were on their way out. To the right is the turbo transition control. It is mapped based on rpm and throttle position sensor voltage. On the right is the transition rpm point during acceleration. To the left of that is the transition point back to sequential mode during deceleration (hysteresis control). There is a trick where you set these values very close together to a low rpm and the PFC will control boost on a single turbo.

On the left side of the screen shows the log. Top is rpm. Middle is manifold pressure (Pressure Intake Manifold) load coordinates where 20000 is approximately 15psi with the way the MAP sensor is scaled. On the bottom is boost control solenoid duty cycle, where 255 = 100% duty and 0 = 0% duty.

hope that clears some things up.

If this kind of thing isn't for you, take thewird's advice and buy something like a Greddy Profec S. You just turn a couple knobs.

beat to it by arghx

Hi Arghx,

Thanks for the very detailed and interesting post - i was hoping you might turn up, i've read your other threads on the PFC control. :)

It is my intention to next get the Datalogit software.

at the moment i've put all 4 turbo settings to 0.75 and primary at 44% Duty and Secondary at 48%, this is giving me a 10-8-10 pattern.

Do you know what the function of having 2 'primary' and 'secondary' settings is? Is it for the learning that is mentioned in the FC manual?

I'm currently reading your other posts at the moment as i seem to be suffering the Hunting and high idle that is common after installing the Apexi and FC....:scratch:

Thanks

I don't like using the boost feature to control boost since it also controls your fuel cut. Use it at your choice.

Hunting can be fixed my raising the F/C values. For stock port engines, I usually set it to 1200 RPM and street ports 1400 RPM. Values are obviously not a set rule but usually those work. If your idle is still higher then your idle settings and won't come down, there is something else wrong. Did you cut the 4 wires when you installed the PowerFC (assuming its a LHD)?

thewird

You have two boost choices. If you go into the commander you'll be able to select them. One boost choice could be your high boost and one could be your low boost. I like to have a summer and winter setting. The winter setting has much lower duty cycle values to prevent spiking.

Within those two boost choices, you have independent control over prespool and wastegate function. Often you're fine just setting the "Pri" and "Sc" values the same, but you do have the option to tweak them individually. The duty cycle curves are coordinated with the turbo transition logic, whereas an external controller is not. As I've said before though, the Power FC is not the simplest boost controller to adjust.

I have written extensively on the idle issues. Search for threads I've started in this section.

Yes, that adds some complexity to adjusting the values. It should have been a separate fuel cut setting all along. Using the PFC is not the simplest solution, but you do get independent control of prespool and wastegate operation and you can log the duty cycle curves.

ok, i follow, however i don't see in the commander any way to 'set' what boost setting you are on, whether it's 1 or 2...

Hi again, thanks for the input,

This is a JDM import into the UK so i didn't have to cut any wires.

My manual idle set screw is about 1/4 turn out, however i need to check my dashpot functionality and also check whether the TPS voltages change when it's warmed up and i move the thermowax assembly.

Before i put in the Apexi and FC in was aware that it idled at 1100 so i think there's probably underlying issues i need to resolve before fiddling with F/C levels.

My bet is that the thermowax is still pushing the butterfly's open a little even once it's warmed up.

Instructions bro (Google it)...

https://www.rx7club.com/attachment.p...1&d=1341442351

Ya ya man, i have that in the manual, but it doesn't 'highlight' or keep which setting you're on. :)

I'll go out tomorrow to my test road and make a high boost and a low boost setting and report back. :icon_tup:

The setting its on is the one that its on when you come in and again when you leave.

thewird

Sorry, what?

Sorry lol, on my phone. The boost setting that is selected will be the one that's highlighted when you go in. When you leave that screen, the setting that's selected when you leave will be the one that is "set". Hope that makes more sense LOL.

thewird

Absolutely,

Now it is crystal clear - i think tomorrow i'll drop setting 1 down, and put setting 2 to what setting 1 is now, and then do a few runs switching between the pair to confirm. :lol:

Well, i removed the mechanical dashpot and that seems to be my car idling very well now.

I've also upped the FC settings in the idle to 1280 (as per arghx other thread) so i get a nice hold of RPM when going into neutral, and then it drops to 720rpm when idling, so it's pretty spot on!

If you have an aftermarket clutch and flywheel you do have a potential for stalling on deceleration. I personally would have just loosened it up to the point where it's not doing anything rather than take it out completely. You may have to tinker with it when the weather changes.

The closer your engine is to stock, the less temperamental it tends to be.

my fav quote