Boost Limit Question

reid-o · 05-26-2006, 12:25 PM

The concensus seems to be that the ECU can only read up to 18.5 psi, so if that's the case, then by raising boost limit past this, am I sort of disabling fuel cut altogether?

Or does it calculate by subracting 14.7 from absolute?

Sorry if this sounds like a noob question, but it just sort of occured to me now.

overdose · 05-26-2006, 01:36 PM

it subtracts

daemon · 05-27-2006, 04:28 PM

Yeah. The ECU knows the real boost (up to the MAP sensor limit, don't recall what that is, but it is over 22psi I believe). The 18.42 limitation is just with the protocol used to read relative pressure via the OBD-II port.

RacerXS · 06-01-2006, 07:51 AM

Pretty sure it's 21. Mine started wigging out past this, also what I have heard from others.

TheMadScientist · 06-01-2006, 08:08 AM

24.8psi is the sensor limit, once you start to get close to the limit the reading will start to get funky.

TMS

05-26-2006, 12:25 PM	#1
reid-o Senior STI Driver Car: 04 Black STI Location: Mililani Hawaii Posts: 330 Join Date: Dec 2005 Trader Rating: (3)	Boost Limit Question The concensus seems to be that the ECU can only read up to 18.5 psi, so if that's the case, then by raising boost limit past this, am I sort of disabling fuel cut altogether? Or does it calculate by subracting 14.7 from absolute? Sorry if this sounds like a noob question, but it just sort of occured to me now. This ad is not endorsed by this member. Please register or login to hide this ad. Last edited by reid-o : 05-26-2006 at 12:28 PM.

06-01-2006, 08:08 AM	#5
TheMadScientist Professional STI Racer Posts: 601 Join Date: Apr 2004 Trader Rating: (0)	24.8psi is the sensor limit, once you start to get close to the limit the reading will start to get funky. TMS This ad is not endorsed by this member. Please register or login to hide this ad.

05-26-2006, 01:36 PM	#2
overdose Senior STI Driver Car: 2005 WRB STi Fav Mod: roadhead Location: Grand Rapids, MI Posts: 314 Join Date: Dec 2005 Trader Rating: (0)	it subtracts

05-27-2006, 04:28 PM	#3
daemon The Next Petter Solberg Car: 2004 STi Location: Florida Posts: 865 Join Date: Feb 2004 Trader Rating: (0)	Yeah. The ECU knows the real boost (up to the MAP sensor limit, don't recall what that is, but it is over 22psi I believe). The 18.42 limitation is just with the protocol used to read relative pressure via the OBD-II port.

06-01-2006, 07:51 AM	#4
RacerXS S204 Racer Car: 05' Sti Black Fav Mod: Dyslexia Location: Central, NJ Posts: 3,362 Join Date: Oct 2004 Trader Rating: (13)	Pretty sure it's 21. Mine started wigging out past this, also what I have heard from others.