MichaelFregoe

iTrader: (1)

Easier fix. Replace the PFC with a re-chipped Mazda computer.

I know that is a smart @ss answer but It is the best solution.

BTW. The PFC has sensitivities to other voltages as well.. In my car the PFC didn't recognize the voltages from the neutral switch and the car would remain in a condition with both turbo's running at 2K RPM or less. I replaced the PFC and both problems went away. I also swapped PFC's and found it was my car and not the specific PFC I had.

I do not mean to PFC bash…

MichaelFregoe

iTrader: (1)

I just re-read what I wrote above.. instead of "2K" it should read "3 - 4.5K RPM".

Riccardo

iTrader: (1)

Easier fix. Replace the PFC with a re-chipped Mazda computer.

I know that is a smart @ss answer but It is the best solution.

That is probably OK for some people...however for others it is not
As for the other problem did you check your harnes ?

MichaelFregoe

iTrader: (1)

I checked everything... I called around to several well known RX shops and spoke to some guy whom knows the guy whom wrote the software for the PFC... And yes... the Neutral switch affects the transition from 2 turbo operation back to single turbo operation. I did extensive testing.... The issue was that the PFC is sensitive to the neutral switch voltages as it is with the A/C signal voltages. Just another reason to avoid the half engineered aftermarket POS. I can see having one if you want that extra 5-10 HP from tuning to the ragged edge, running very high boost, or went single turbo. Otherwise the reliability of a re-chipped Mazda unit can't be beat.

When switching back to the Mazda unit... All the A/C issues went away.. The turbo's transition perfectly normal once again. HP levels stayed the same. My car made 300 HP to the wheels @ 11.5 PSI on a 90 degree Florida day. (sea level)…. That’s with a STOCK Mazda catalytic converter. With an 11.5 A/F all the way across the RPM band.


PLUS I no longer had the drivability issues the tune in my PFC was giving me. I admit the tune on my car was poorly tuned by KD. I could never get with Steve Kan for a proper tune. I am sure his tune would have cleared up the DETONATION issues the PFC was giving me all the time under heavy load and mid RPM. But the A/C issues and the transition issue made owning the car totally un-enjoyable.

My 2 cents.

moconnor

iTrader: (14)

Huh - you are not making much sense, dude. The PFC has been around for years and is already proven as an extremely high quality well engineered reliable unit. Its only very minor issue is that AC does not necessarily work on all settings on some cars, a problem that has many workarounds.

The neautral switch problem you outlined I have never seen reported elsewhere, which would obviously indicate that your car had components that were well outside of tolerance. The pre-detonation issue that you mention is almost certainly the result of bad tuning.

The Mazda unit that you tout has the far more serious tolerance issue that causes a 3k rpm hesitation in a significant number of cars. In fact, it is the primary reason I am buying a PFC.

Chosing a rechipped Mazda ECU only makes sense if your car does not have a 3k rpm hesitation and if you have a fixed set of modifications that are never going to change. Few FD owners are in that state I would imagine.

MichaelFregoe

iTrader: (1)

I have seen or heard about very few cars not having at least some issues with the A/C when running a PFC.

The 3K hesitation you speak of is really no concern because it is far more rare than the PFC A/C issue and is usually easily corrected with a ground wire.

I can't imagine the reason for a PFC with a sequential car. I am sure that the issues I had with the neutral switch is far more common than most people realize. I found it because I am very in tune with my cars. (yes car(s), plural). I currently own 3 RX-7's and am getting another soon. The shop I spoke with actually said they have seen the issue before and most people do not even notice their car has it.

My comment on "Half engineered" means.... Knowing the issues with the A/C and idle... Apexi would ideally make the software corrections for the newer units... But they have not, so that = "Half engineered"


Here’s the deal:

On a sequential car with a ported motor and all the bolt on's.... You still can't run high boost (>14 PSI) reliably with a PFC because of creep issues and the limitation of the stock turbo's. (even with a ported wastegate). So a Cat must be retained or restrictor plates installed to limit flow (Talk about 2 steps forward and one step back). You might as well get a re-chipped Mazda computer (that by the way.... Maintains all the diagnostics AND runs the metering oil pump correctly) (The metering pump has been proven not to be 100% with the PFC by several big name shops... And I noticed the oil consumption in my car fell off with the PFC)

If you go single turbo.. Then by all means.. Get a PFC and keep from having to re-wire your entire engine bay.




Mazda re-chip:

Pro's: Great drivability, smooth idle, no tuning issues (the car runs great at 20 degrees and at 120 degrees), will run all the bolt on's even with a ported motor. A/C works correctly with all the A/C features (delayed activation at start up, shuts off at WOT), turbo controls work correctly. SAFE on the motor!

Cons: Runs a little rich (11.5 : 1) causing loss of peak HP.


PFC:
Pro's: Allows tuning to the edge for optimum power with your mods. (If you can do it yourself), cool keypad to impress your Honda buddies (I did like the display to see the states of all the solenoid controls)

Cons:
A/C will most likely be affected, Turbo transition (back from sequential to single) can be affected, Performance highly dependant on the skills of the tuner (tuning can be very expensive and you might be waiting for months for a proper tune), Self tuning requires the purchase of a wideband o2 system, Does not control boost very well so a separate boost controller must be utilized. Idle issues, Oil metering pump issues, more expensive than a re-chip.


Summery.... If you are a racer or a track guy and are serious about it... Get a PFC...

If you are the average guy whom wants to get the safest HP out of your car without having to be concerned about constantly blowing your engine get a Re-chip. Plug and play.

I know you spent good money on the PFC (and so did I at one time) and are defensive on your purchase. But the PFC really isn't for that average guy on the street. Gaining the last possible 10 HP out of your car isn't worth the headache.

I believe the PFC documentation says it isn't intended for street use anyway.

moconnor

iTrader: (14)

The 3k hesitation is a huge concern for me and many other people and it is not simply cured by "a" ground wire. Do a search for "hesitation" if you want to see the range of things people have tried to no avail. I have redone all my grounds (as have many other people) and it made no difference. For a small minority of people this works. Others have gone as far as cleaning injectors and swapping ECUs (including re-chipped Mazda ones) and the problem remains. The only 100% reliable cure that I have read of is the PFC. Or swapping in a new engine harness (currently $700 from Mazda).

You must not have had this hesitation on any of your FDs because if you had you would not dismiss it lightly. It is a serious drivability issue and got significantly worse in my car when I added an exhaust and modified the stock airbox.
That would make almost every product ever released "half engineered". In an ideal world, manufacturers would correct any problems they find in later iterations of a product. In practice, the don't for a variety of reasons. It would be nice, for example, if Mazda rewrote the software for their ECU to solve the 3k rpm hesitation. In fact, it would be even nicer if they had multiple recalls to fix the ridiculous array of shortcomings in a factory FD. The FD would be the most quintessentially "half engineered" car ever released under your definition.
You cant' run more than 14 psi with the stock twins reliably with any ECU - they are not designed to operate in that range.
Of course there are no tuning issues with a Mazda re-chip - that is because you can't tune the damn thing! That is a bit like claiming that an instant disposable camera is superior to a $2000 digital camera because you will never get the exposure wrong because it does not have complex controls. Flexibility always comes at the price of some complexity.
Which is the whole point and is the main reason people buy them. Mazda re-chips are typically tuned for the standard bolt-ons at 12 psi or with a consequent rwhp limit of 300 or so. If you go beyond those parameters, you are out of luck.
Few of these are legitimate cons. Again, critizising a PFC because the power you get out of it is dependent on the tuner is like criticising a $2k digital camera because it will not help you take good pictures unless you are a good photographer to begin with. The fact that an O2 sensor is required for tuning is not a disadvantage of the PFC - an O2 sensor it required for any tuning and the only reason a re-chip does not need one is because you can't bloody well tune a re-chip at all. Turbo transition and OMP issues are very rare and may not be PFC problems. A PFC is more expensive than a re-chip because it is far more powerful than one. (In fact, used PFCs without Commanders are now selling for $500 or so, which is only marginally more than used re-chips; new re-chips now cost more than new PFCs without a Commander.)
I don't think I have ever seen defensiveness from PFC buyers. It is one of those product that very few people are unhappy with after buying. You clearly had a bad experience and are now touting far more limited product as an alternative.
This is just silly. The 'street usage' disclaimer is standard legal boilerplate on many aftermarket products. In fact, last week I received a 12V relay from Summit and they had a disclaimer on the invoice next to it saying that it 'was not for street use'.

MichaelFregoe

iTrader: (1)

You forgot to comment on my most important statement of all:

I'll quote myself:

"Summery.... If you are a racer or a track guy and are serious about it... Get a PFC...

If you are the average guy whom wants to get the safest HP out of your car without having to be concerned about constantly blowing your engine get a Re-chip. Plug and play."

It is called "SUMMERY" for a reason!

Digital camera's???? Comparing apples to oranges.......... Gain your last 10 HP and when you need an engine ask some of these so called "experts" here on the forum for re-build advice. Some guys (and gals) know loads of useful information. Many are armed with just enough information to be dangerous. Unfortunately the number of posts someone makes does not make them knowledgeable....

moconnor

iTrader: (14)

No - it's called a 'summary'. And if 90% of the arguments used to support a summary are demonstrated to be invalid, then there really is no need to separately rebut it. (And where are these PFC owners that are 'constantly' blowing their engines? They must not post much.)

A significant number of people who are not "a racer or a track guy and are serious" have goals in excess of 300 rwhp. What do you say to these guys?

If you rephrase your argument to "if you do not wish to exceed 300 rwhp, then a re-chip is superior to a PFC" then there is at least the AC issue to argue with. However, given the recent drop in PFC prices, the fact that it allows you to monitor engine functions, set the fan to come on at a lower temperature, improves drivability, and cures the 3k rpm hesitation, it is even a pretty weak argument at that.

Riccardo

iTrader: (1)

Guys cool down, this is a thread to help people with problems with A/C and PFC

Brick

Has anyone changed the (expensive) A/C switch and had it fix the A/C problems? If it is likely to fix the problem, I would think a couple hundred bucks would be worth it to make the A/C work all the time...at least here in Atlanta.

For reference, mine works on the 1st setting and most of the time on the second. It is intermittent on the third and fourth. I can actually see the switch turning on and off on the sensor monitor in the Etc. menu

- J

Riccardo

iTrader: (1)

Brick - pays to read the first post here

- Change Fan Switch (FD0161C50 - USD 92.66)

Worked for some !

Brick

I read it. I was looking for some first hand experience from someone who actually bought and replaced the switch. It seems like most people either bypass the PFC or just live with the problem. I want to figure out if the switch replacement generally works, but people don't do it because of the expense...or if in most cases, it has not fixed the problem so it is worth trying every other lower cost option first.

- J

MichaelFregoe

iTrader: (1)

When I had my PFC I replaced the switch and it changed nothing. The problem still existed.

I know you can remove two wires (I don't have the pin numbers or colors memorized) from the ECU and short them together and the A/C will work.. But... the idle will not raise, the a/c will not cut off at WOT and the delay on starting the car will be gone. I did this for a while but tired of it, that is why I replaced the switch.

I even tried adding an extra ground wire that someone suggested (rx7.com?). It didn't fix it.

I think I know of a way to fix it but since I no longer have the PFC I have not had the chance to try it. It involved putting a simple circuit between the A/C controls on the dash and the ECU (on one of the wires listed above)... therefore making sure the ECU (PFC) is getting the full signal that it should be seeing. ((12vdcwith good current?), no matter what fan position is selected) Like I said.. I had not tried it but I am sure with a little experimenting, the maintenance manual, and some testing I could get it to work

MichaelFregoe

iTrader: (1)

DO Not flame me on this.

This is merely a pet project I never finished. And is based on several assumptions that I have not pursued with a voltmeter.

Basically I think if you splice this circuit into the wire that feeds the ECU the A/C control signal from the dash controls.

I know there are allot of theories about why the PFC is not consistent with every car. My personal theory is that the signal to the PFC needs to “see” must be clean and solid, more than just 12VDC.... I think it needs a good clean 12VDC signal with a little current behind it. This circuit would provide the PFC with a strong and clean 12VDC signal and should make it work correctly on all fan speeds, while maintaing the increased IDLE, WOT cutoff and startup delay features.

Like I said.. I have not tested this, but I think it will work.

MPython

iTrader: (1)

Maybe my memory is wrong (it's not, follow the wiring diagram on page Z-68 of the manual), but I thought the signal coming from the dash (through the fan switch, A/C switch, and thermoswitch) is actually a ground coming in on a violet wire. The yellow/black wire going to the A/C relay at the front of the car is also a ground. The suggestions we've been reading about is to tie the violet wire to the yellow/black wire. I did this, and it works (after converting my system to R134a, replacing the receiver/drier and compressor, as both were leaking). You are correct, idle needs to be compensated for manually, and there is no automatic cut-off for WOT. I am going with the suggestion of adding a pressure switch to detect a certain amount of boost (I'm thinking 6 or 8 psi will do it), and cut the ground connection from going to the relay or the PFC. I just need more info before I do that. I'll fix the idle too. Right now, it's real bad... hunting, stalling, but sometimes settling correctly.

MichaelFregoe

iTrader: (1)

I looked at the wiring diagram this morning.

For the A/C relay to switch “on” thus engaging the magnetic clutch the Y/B wire must be grounded through the ECU.

Since when the PFC commander status screen will show the A/C circle not darkened when it should have been darkened on the “bad” fan positions. We can determine that the PFC is not “seeing” the signal (violet wire) from the fan controls and A/C switch (on the dash) properly and therefore not grounding the Y/B signal when it should be. (This would prevent the other niceties of the CPU circuit from functioning…. increased idle, WOT cutout, delayed A/C upon startup)

The question is:

What signal is on the violet wire? What is the quality of that signal? Grounding violet should turn on the A/C. I’ll call this the control signal.


The Violet (V) wire changes color codes several times from the ECU before getting to the fan switch. Before it enters the fan it actually becomes L/Y (blue/yellow) this is after connector G-08 (Thermo switch connector).

I propose the following modification to permanently resolve all PFC related A/C issues while maintaining the full ECU controls on the A/C:

1) Disconnect (I hate the word “cut”) the Yellow/Black and Violet wires from the ECU. Connect them together… (This is currently considered a fix by some, “ECU Bypass”)

2) Make sure you leave enough Violet wire coming from the ECU so you can make a connection to this later.

3) Get a good 12v relay, cut the Blue/Yellow wire coming from the Thermoswitch and put the relay coil in series with this circuit.

At this point we have the system working like the “ECU bypass” fix. The A/C will work on all fan speeds but the ECU will not “see” the A/C being on because the control signal is being routed around the ECU (hence Bypass). We will correct this by using the poles of the relay to ground the Violet wire remaining (coming off of the ECU) to through the relay contacts.

4) Connect the Violet wire from the ECU (this should be not connected to anything) to the normally open portion contact of your relay.

5) Connect a wire to ground from the movable contact on the relay.

Theory of operation:

When the A/C button is pressed the “ECU bypass fix” is in operation (A/C works in all fan speeds). The added relay sees the flow of electricity and trips the contacts internally and grounds out the Violet wire so that the ECU “sees” the A/C on and functions the idle to a higher setting.

What this will not do… It will not delay A/C activation at startup or do a WOT cutout.

Adding another relay to interrupt the Black/ Blue (under hood) (connected to the 2nd relays normally closed contacts) should resolve the A/C delay at startup and WOT condition. The coil of the 2nd relay should get power from the grounding wire of the 1st relay.

I wish I still had my PFC to test this. I have a strong feeling that this will work because what this essentially does is provide a good ground to the control signal (Violet) wire, without all the other stuff in the dash confusing it.


Again. I did not write this to be flamed. I was toying with this idea for months when I had my PFC and never got around to actually doing it. THIS HAS NOT BEEn TESTED. DO SO AT YOUR OWN RISK. <<<self protection legal necessity. LOL!>>>

MichaelFregoe

iTrader: (1)

Diagram for PFC fix

MPython

iTrader: (1)

I think your theory will work. Simply put, provide a good ground to the PFC for A/C control when it's activated, and let it do the rest. I suggest testing this theory out by leaving the Y/B wire connected to the PFC, and simply ground the violet wire or the pin at the PFC it connects to. This will prove whether this will work or not, without adding that hardware. Obviously, do this under the right conditions (mainly, engine on and blower fan running). Also, check to see if the A/C indicator comes on in the PFC etc. menu.

I would check this myself, but my Y/B wire is already cut and soldered to my violet wire. I know my PFC doesn't indicate A/C on when it is on, so the ground it's getting isn't good enough for the PFC, but is good enough to engage the A/C relay. I'd like to see someone prove that the A/C indicator on the PFC can actually come on. And then to do the other things it should do (start-up, WOT, idling).

MichaelFregoe

iTrader: (1)

I think you are in a good positon to test this. By grounding the Violet wire as it exits the PFC. I would do it though a coil of a relay just so that there is some "load" on it.

When you ground it I am 99% sure that your A/C indicator on the PFC moniter screen will come on. Plus it will verify the relay / coil portion of my fix.

MPython

iTrader: (1)

You are right, there does need to be a load on that ground. The fan switch usually provides that load, as it has resistors in it to set the fan speed (except speed 1).

MichaelFregoe

iTrader: (1)

It probably can go without a load I would do it just to be on the safe side. The fact that the Y/B wire can be connected directly to it (violet) makes me think that it would be OK just to ground it but better safe than sorry.

MPython

iTrader: (1)

Ah, but the violet wire goes through many devices, and when the fan switch is on, goes through those resistors. So there is a load there, even if just a small one for fan speed 1.

wolftj

I have a 95 RX-7 and after installing the PFC I have no issues with the A/C. Is there a difference in my car vs. the others in this thread because of my 12/95 build date? Might be worth checking into. Good luck.

HDP

iTrader: (2)

Mine only blows cold on 1 & 2 but not on 3 & 4. If I put the A/C switch in between 3 & 4 only then will it sometimes blow cold. While observing the commander I discovered something the other night. On fan speeds 1 & 2 the A/C indicator light on the commander comes on and it blows cold. But on fan speeds 3 & 4, the A/C indicator light goes off, but the ELD indicator light comes on. Does anyone know what this mean?