Tim Benton

iTrader: (1)

okay, I'm tired of the fuel cut. I'm not going to change pills unless I have to since its a pain in the *** to change them, do some runs, change them again, etc. So I'm going with the Dawes device setup to control boost to 12 psi to 13 psi. On the PFC, do I go into the seq. setup and turn them off, or is that just for when you go non-seq.? Or like it says in the last sentence, just set it for higher than what I am going to run with the dawes device?

Tim Benton
Not going to take chances with the PFC's inability to control boost in cold weather

cewrx7r1

iTrader: (2)

I have the HALLMAN device which came out years before the cheaper Dawes but controls boost the same way. It replaces the WG control system or even could be used in series with it. It is a spring loaded pressure valve that does no bleed off boost pressure until the pressure exceeds the adjusted pressure. It's main purpose was not to control boost (which it can by itself) but to help spoolup by not bleeding off boost until needed. The stock ecu and solenoid control is always bleeding off boost at some cyclic rate.

EVEN WITH IT, YOU WILL STILL HAVE BOOST CHANGES DUE TO TEMP CHANGES.

Unfortunately they industry does not make a boost controller that monitors the map sensor voltage with feedback control to regulate boost at a constant selected level. Such a system would keep boost constant no matter the temperature variations. This neglect by the performance companies has pissed me off for years. You would make "learning" runs which the unit would remember the map sensor voltage. When you reach your desired boost level, this voltage would be permanently saved as the desired voltage. Then the unit compares your actual voltage to saved voltage and either close sor opens the WG to maintane this value. This type of feedback control circuit is so F*** common, that it is a crime that boost controllers do not use it. Instead they are based on using a memorized solenoid duty cycle rate.

If any one knows of such as controller, let us know.

Jodeny

iTrader: (3)

why dont you just raise the fuel cutoff point?
John

ech

Do you mean raise the target boost level, and therefore the cuttoff level?

My experience is that if you are regularly hitting the cuttoff that there is something that isn't working right - but that something might be your wastegate not being large enough if you have a complete open exhaust with a ported engine, etc.

So back to my question. If your answer is to raise the target boost levels, then the PFC will try to adjust to hit those boost levels. The answer, instead should be to fix whatever is broken, if there is anything broken, and also to lower the base duty cycle.

If the base duty cycle is too high for the corresponding target boost number, then you will be more prone to creap and cut. Whenever you get a cut, try reducing the duty cycle for the appropriate trubo, by 4%-8% or so.

Jodeny

iTrader: (3)

Is your duty cycle at it's lowest?? (20%) Let me know and then, once again, I'll attempt to help.
John

Tim Benton

iTrader: (1)

From an earlier post, I was running stable boost around .82 to .84 in warm weather. Weather got cold, boost went nuts. Its set at .8 prim. 8 sec. on the frst boost setting. I started hitting fuel cut from overboosting, lowered the damn duty cycles all the way to 20, didn't do a damn thing other than make boost seem kinda slow coming on, but it would still go over the .25 that makes it hit fue cut. I'm not going to raise the boost number and find out, that hey, it still doesn't control boost worth a damn in cold weather and guess what, my injectors can't supply enough fuel for the new higher boost setting plus the additional .25 over it. Blown motors happen that way
any input would be helpful, but like Chuck stated, we need something like he said, not something that you need to tune every weather change.

Tim Benton
mods- intake, ypipe, DP, resonated MP, catback as far as flow mods go.

Jodeny

iTrader: (3)

You have plenty of fuel to run 14-15 pounds so don't panic. I would upgrade the fuel pump if I were you (do not get the walbro.) Your pill(orifice) is too small and that is why you cannot control boost. Take the wastegate hose and install an adjustable valve in it, start with it fully open (lowest boost). Close it until you get the desired boost that you want. I had the same problem with the PFC a couple of years ago and this worked VERY well. I now can adjust the twins from 11 pounds to 20.
John

adax

iTrader: (2)

Tim,

What you are describing sounds more like boost creep than a problem with the PFC. No controller will fix that. I was having the exact same problem on cold days once I added an IC to the mods you have (less the Y pipe). Installing a high flow cat and a 2.5" exhaust gasket solved the problem at no subjective loss of power.

Alan

KZ1

Tim,

are you saying that you consistently see over 1.1 kg/cm2. becasue at .85 that woudl be boost cut. try raising the boost to .9, with your setup adn cold weather it will be tough as you know to keep boost down b/c of wg system. so you have 3 options, run higher boost, take some mods off, try and port wg and see if that works. Jusrt turn it up to .9 kg/cm2, an drun your injectors at 94%

Tim Benton

iTrader: (1)

mine was at .8 for the first boost setting, so I was hitting 1.06 plus and hitting fuel cut. I did raise it to .85 and so far I haven't hit fuel cut, but I don't want to be running the turbos that hard for long since they'll wear themselves out faster. Granted it would be more fun at the higher boost level, but the cost of replacing the turbos isn't fun.

Leaving it at .85 for now, until warmer weather.

Tim Benton

ech

I still suspect that something isn't perfect, like a lazy solenoid (stab in the dark). The PFC should be able to controll boost better than that - even in cold weather.

Jodeny

iTrader: (3)

ITS THE SIZE OF THE ORIFICE, I HAVE BEEN THROUGHT THIS BEFORE!!!!!!! The PFC has EXCELLENT BOOST CONTROL.
John
This is not directed at ech

Tim Benton

iTrader: (1)

So, what needs to come off the car to make the orifice bigger by drilling it out? Turbo manifold? and all the things before it?

Tim Benton

Jodeny

iTrader: (3)

No, you are thinking of the wastegate. Just take off the wastegate hose (short one) and put on a vacuum hose without any pill. If your boost stays low then you know the pill is too small.
John