i think it depends on what type of setup you have. When i installed new injectors my boost went up to 30. then i had to retune my MBC

 

Yea any mods can make it change ... I have had to retune mine a couple of times.

 

There have been some questions as to the difference in where to draw the "pressure source" from.

For our installs, we require two pressure sources. One is for the solenoid valve (the black box with "COM", "NC", and "NO"), and the other is for the connection to the Greddy unit itself inside the cabin. The two places to draw pressure from are the intake manifold (which is where the fuel pressure regulator and bov get their pressure) and the turbo compressor.

The difference between the two is that the pressure is not the same at all times between the two. The psi at the compressor will be higher than the psi in the intake manifold because the intake manifold is receiving the psi that is left after it travels away from the compressor, through the intercooler, through the pipes, and finally into the intake manifold. The psi at the compressor is the full pressure before any loss that occurs on its way to the engine. The psi at the intake manifold is the actual pressure entering the engine. If the psi at the compressor is 20, the psi at the intake manifold might be 18 or 19.

The reason you want the pressure source for the solenoid valve to come from the compressor is that you want the solenoid to controll the highest pressure reading, which is right at the compressor. The reason you want the pressure source for the unit itself to come from the intake manifold is because you want the readings that you see and use to tune to be what's actually going into the engine. This way, you tune for what psi your engine is seeing, not what psi your compressor is seeing.

Some have asked for a diagram as to where the vac lins go to and from. This may help a lil:

 

My low setting is set 45%, Gain 8%, Startboost 140, Warning 225, Lower 10%. For me I hit 20.3 psi all day long. I keep that setting for the cold weather. I understand how everything works on the profec exept the Startboost. Can someone explain to me what that is.

 

leave startboost at 140, thats what Turbotrix did to my, and tune up the gain to 10

 

startboost is at what psi the greddy takes over
at least thats how i understood it from the vague explanation it gives in the manual

 

Hey all, just when I thought I had it, I don't.

What I am trying to accomplish is: HI Boost 22psi to redline
LO Boost 19 psi to redline

My current settings are:
HI Boost: 56
Gain 10%
Set gain 90
Warning 225
L. 4% (???????)

LO boost 52
gain 10%
set gain 90
warning 225

Can someone lead me to in the right direction?

 

if u don't have a standalone, DO not use two settings. what boost was ur car tuned at? stock ECU can only one map, theres no use for two settings.

 

I was flashed for 22psi by AMS. I just wanted the lo boost level to be at 19.

I understand what you are saying to the fullest, but one of my numb nutted friends started to figit with the controller while I was in Starbucks, and just wanted to make sure things looked kosher.

 

That's not true at all. You could use Low boost for those super cold mornings (to prevent overboosting). Or, you could drop a couple psi for track duty (to have as a safety margin). Tune your ECU for the high boost setting, then use the low boost setting for something whatever you need. Reducing the boost a touch isn't going to suddenly destroy your tune.. you'll just run a tiny bit richer (still nowhere near as rich as the stock ECU cal though).

 

So then if the startboost was at 140 that means the profec takes over at 14 psi?

 

yup that is the case
profec takes over at 14psi

 

If thats the case wouldn't it make sense for the profec to take over at around 120 or 11-12 psi. Isn't that the highest the waste gate uses?

 

kreionic makes a good point. So why is it suggested to get it as close to the "desired boost pressure" as possible? just curious...still having issues with mine and getting inconsistant boost levels...(grumble,grumble,grumble....)

 

well if you set it any higher i dont think itll work
turn off your profec and it will only hit about 14- 15 psi
if you set it to 18 psi it will never hit it and the greddy wont take over