well i just re-installed my greddy profec (i went MBC for a bit) and i cant get rid of the taper. Even if i start at around 30% with 5% gain, im getting taper of around 2 psi at like 5k rpm. I get spiking sometimes, but its not all the time, im thinking i have another boost leak...i just had the throttle body shaft seals replaced, but maybe theres another leak somewhere.

any thoughts anyone?

(dont go by my mod list...its all changed now but i'm still on stock turbo w/ 10.5 ....just had no time to update it)

 

Could be a boost leak; but keep in mind that only about 1 in 500 cars are able to completely get rid of the taper (Chris Black, AMS). Even though my gauge shows no variance in boost at higher rpms I've got a minute amount of taper too (which I only found out about during a recent tuning session).

Take down the start boost (set gain) to around 14 psi, your spool up will be crap but if you starting surging than you know it wont be because of that setting.

Next, set your gain back down to 5%. Go do a third gear run (or a run through however many gears you want). If there is still taper than bump it up a couple notches and take the car out again. Continue this process till one of two things happen: you either get rid of the taper -- or you start comp surging. If you start comp surging before the taper is removed, than you're not going to be able to completely remove the taper with your current setup (assuming like you said there's nothing else wrong with the car).

After you do that, go and configure your set amount -- it will probably be somewhere in the 65-75% range if you're looking for anything betweeen stock boost and 23 psi. This setting won't cause any surging so you just set it to your liking.

The start boost is basically spool up response. The higher the better. You want this to be as close to your set amount as you can get it. Do the same thing that you did with the gain. Set it, run it, increase it, run it, increase it, etc. When you hit the comp surge, take it down in small increments until it subsides.

That's all you can do with this thing man. On another note, if your lack of boost up top is due to a boost leak, you may want to get a wideband to make doubly sure. When you lose boost you will inherently go rich because the MAF is showing a large amount of air and the ECU is shoving the appropriate amount of fuel in--if the air supply after the MAF is leaking out you'll be running very very rich. If it's normal/standard operation you should still be around the proper 10-11 afr at high rpm wot.

p.s. I didn't make mention of this but make sure to have your warning and limiter set accordingly as well so that you don't overboost.

 

Slightly off topic but, Tuning this Profec. Is there a Differences in Tuning the profec with a Subie Wrx verus a Evo? a friend of mine says there is but I highly doubt it cause its using the same system.


thanks for any comments

 

hi guys, my greddy do somethink intresting:at low rpms boost 1.3, at middle 1.1, and at high 1.2 is it normal?

 

This has helped me okt alot. Thanks for this thread.

 

This is a great write up! I am still a little confused about the SET GAIN though. You say you set it to 18.5 PSI or the like but on the unit it doesn't say PSI it gives the numbers 1-100something. So how do you figure out what PSI the SET GAIN is at?

 

If you have in set in PSI mode and you want the set gain at 18.5 put it to 185. Some reason it doesn't put the decimal point in.

And now to a question I have, I'm running 28psi on a 35R with a Tial 44mm wastegate(not sure which spring). My settings in PSI mode are: set gain at 280 gain at 10% and set at 72%. I'm hitting my target boost pressure but I was looking to get it there as quick as possible so when I shift and go WOT there is minimal spool time. My question is will increasing the gain get it to 28psi quicker? I know increasing the gain will in turn increase boost and is more for stablizing boost drop off but will it spool it quicker? Should I lower my set% and raise my gain?

 

can you under boost? to save gas? lol

 

how do i set it on psi!!!!!????

 

Im having the same problem ... where is the cap thats on the NC terminal .. is it on the EBC itself or under the hood? please let me know!

 

bump

 

someone must know this ..

 

ok i checked on the cap on the solenoid and its off ..

i still cant boost past 25psi .. whats the problem?

 

I'd like to know how to check if the cap is there...

I have a really bad spike issue. When I set off at WOT from, say, 2000rpms in 3rd, the boost spikes all the way up to 1.8 before settling and holding at 1.4 bar like I want. Does this in every gear. Have tried fidding with the settings as much as I can think - tried putting the set at 0, lowering the warning, increasing the limiter, setting the gain to 5, etc.

Nothing I do seems to stop the initial spike to 1.8 though. After the spike it immediately goes down to whatever level I set - be it 1.1, 1.2, 1.3, 1.4, 1.5 bar etc. but the spike seems to be uncorrectable so I'm thinking that is may be an issue of having the "cap" on etc.

My settings are:

set 65 (works out to about 1.4 bar on my car)
gain 10
set gain 1.30
warning 1.40
limiter 2

Am I doing something terribly wrong here?

Any help apprecuated.

 

how do u change the Kpa to PSI ?