After a couple runs to or near max boost, my car will not build boost much about 8 psi. I off/on the key and it builds max boost again. My friend says it's the PFC and they all do it. Seems hard to believe as I would think the product would be off the market if true.

Has anyone else had a similar problem? If so how did you fix it? Or did you?

 

I'm just grasping at straws, but I know the PFC has a self learning boost function where it adjusts the duty cycle to try to match your target boosts. Maybe you had your targets too low and were using the duty cycle to get the high boost?

I haven't ever seen anything like this mentioned before, so I don't think it's related to the PFC. I have several friends running a bar of boost regularly using a PFC.

 

8psi sounds more like a boost pill problem .. not PowerFC.

 

spyfish, interesting point. It does work right sometimes. In fact it's been working better lately. Still a PIA. Man I hope someone knows how to fix this.

 

I had the same problems i replaced my solienoids and redid my vac lines for the third time and now it works fine

 

If you are referring to the boost pattern where you punch it hard, hold it WOT till past 6K, then let off and then try to WOT it again and only builds boost VERY SLOWLY or only makes about 6 to 8? Makes alot off noise but no acceleration?

Tim

 

Tim,

That's about it. What is happening?!?!? I was thinking it's a flakey check valve or solenoid. A friend of mine who has seen hundreds of FD says all P-FC's do this. I don't know anyone who knows more about FD's. Maybe I'll just have to drive down to XS and have them check it out.

Thanks.

 

If my memory serves me right from my days long ago on the big list, its a defect in the system itself. At the time, most people either had the PFS PMC or a rechipped ecu, either way the wastegate duty cycles were still ecu controlled. What people thought the problem was and I think I agree with the reasoning is the mazda engineers programmed the ecu so that high load /high rpm runs would make the wastegate stay open, so when you let off the throttle then lay back into it, the wastegate is still open, venting boost, which is why it makes all the noise but builds boost slowly. On my car, I've had the PFS PMC, M2 stage 3 ecu, and the PFC now and all 3 do it. I can be in 4th gear, run it hard up to 6500 rpms, let off then stomp it back in and it'll sound like its going fast, but a majority of the exhaust gases are going by the turbos. If I push in the clutch, leave it in the same gear and then stomp it again, its fine. Its just that WOT, let off, WOT that doesn't make a boost quickly the second WOT. As far as what you can do about it, well I've had all 3 ecu's and found nothing that works other than shifting, same gear, down or up to be the only way for it not to do that other than waiting like WOT, let of, waiting, then WOT so that the wastegate is now closed.

Any other ideas, since its been a few years since I was on the big list, maybe its been rehashed on it since I've been off.

Tim
owned my 93 since 94, still love the freakin' thing too

 

Hmmm, does it HAVE to be after WOT? I've been noticing, and discussing with friends that have noticed the same thing, that occasionally while cruising down the highway, the car will be very loud and seem to not be as responsive. I have a highflow cat, DP, and catback, so I seem to notice this problem the most at 60mph because everything really seems to resonate at that speed. Then after a few minutes the exhaust note will get significantly quieter and everything will return to normal. Weird.

 

IT does not only happen at WOT. I think I do have to do one run at WOT then any effort to build boost over 5-8 psi just does not work.

I think we may be having two different problems. Myabe not. The best part of all is it has not happened for a few days. I have not been driving fast very much but I did a couple runs through 3rd yesterday and it did boost to about 12psi on the second run.

I think at this point it's something specific to my car or a small group of cars. I thin it's strange that my friend, who should know his ****, has the same peoblem and thinks it's the P-FC.

It's most noticable on the freeway. Just do a run to about 90 or so (hypothetically ) with the hammer down, then try to hit it from 50 or 60 to 90 and see if you get boost. After one or two short freeway blasts, I frequently have to KOKO to get any boost. KOKO will fix it. WEIRD

 

I should restate it a little, hammer it enough to get to 10 psi and let off and then toeing it in again to try and get 10 psi and it takes forever to get there, acceleration wise and also boost wise.

Tim

 

Tim,

Yup that's it. really a pisser when you are merging on the freeway, drop into the left lane and .......... enginer room is not responding. Let alone it makes street light drag races highly speculative

I still don't have a fix and my mechanic thinks it systemic to the PFC so he's not going to try fix anything. I think there's likely another cause but I'm stumped.

 

email dave at kdr he will help......7 sins had the same problem

 

Ok I'll try. I wonder if he will help even though I never bought aything from them. Not a slam, buisness is buisness.

This is really getting old. I just did a run up 280 to woodside and every time I let off the throttle all the way I can only get 8 psi. After KOKO it's back to 13 psi.
Can't wait to get this **** fixed.

 

Like mentioned earlier if what your experiencing is what we think it is all the ecu's do this. I dont think its a pfc thing.

 

Actually it is sticking in non-seq mode. Either one of your solenoid/vacuum lines or wastegate/exhaust 'trap doors'(I cant think of the actual names, it late) are sticking
J