How the ECU reads Boost...MAP sensor Q
06-10-2004, 09:16 PM
#1
1.5 BAR
Thread Starter
Join Date: Sep 2003
Posts: 660
How the ECU reads Boost...MAP sensor Q
Does the ECU automatically calibrate itself to detect ambient air pressure at different elevation levels? For instance, at sea level atmospheric pressure is 14.7
PSI. In colorado, atmospheric pressure is 12.2. SO, would the ECU/MAP sensor (in colorado) see 2.5 PSI of boost as Atmospheric since 12.2 + 2.5 = 14.7? or does it know what ambient is, and adjust?
PSI. In colorado, atmospheric pressure is 12.2. SO, would the ECU/MAP sensor (in colorado) see 2.5 PSI of boost as Atmospheric since 12.2 + 2.5 = 14.7? or does it know what ambient is, and adjust?
06-10-2004, 09:20 PM
#2
3.0 BAR
Join Date: Apr 2003
Posts: 2,260
Re:How the ECU reads Boost...MAP sensor Q
No.
It reads in _Absolute_ pressure.
Different elevations, will obviously use different MAP values, which is why there are parts on the a fuel/ignition map that you'll never use.
This would be easier to show you with a datalog map trace.
It reads in _Absolute_ pressure.
Different elevations, will obviously use different MAP values, which is why there are parts on the a fuel/ignition map that you'll never use.
This would be easier to show you with a datalog map trace.
06-10-2004, 09:36 PM
#3
1.5 BAR
Join Date: Feb 2004
Posts: 1,039
Re:How the ECU reads Boost...MAP sensor Q
Originally Posted by TurboEF9
No.
It reads in _Absolute_ pressure.
Different elevations, will obviously use different MAP values, which is why there are parts on the a fuel/ignition map that you'll never use.
This would be easier to show you with a datalog map trace.
It reads in _Absolute_ pressure.
Different elevations, will obviously use different MAP values, which is why there are parts on the a fuel/ignition map that you'll never use.
This would be easier to show you with a datalog map trace.
guess i was right
06-10-2004, 09:48 PM
#4
1.5 BAR
Thread Starter
Join Date: Sep 2003
Posts: 660
Re:How the ECU reads Boost...MAP sensor Q
I don't get it...so let's just say this. In uberdata, it shows in/hg and PSI. I believe someone on the uberdata forum told me the formula used was any value above 1000 mBar was converted to PSI, and any value below 1000mbar was converted to in/hg. SO, would this mean that in UD (assuming i am still in colorado), when i am at 2.5 PSI + 12.2 PSI atmospheric, then UD would show I was at atmospheric (0 PSI) due to it's conversion factors? (will post in UD forum also)
06-10-2004, 09:51 PM
#5
1.5 BAR
Join Date: Feb 2004
Posts: 1,039
Re:How the ECU reads Boost...MAP sensor Q
Originally Posted by street_kings
I don't get it...so let's just say this. In uberdata, it shows in/hg and PSI. I believe someone on the uberdata forum told me the formula used was any value above 1000 mBar was converted to PSI, and any value below 1000mbar was converted to in/hg. SO, would this mean that in UD (assuming i am still in colorado), when i am at 2.5 PSI + 12.2 PSI atmospheric, then UD would show I was at atmospheric (0 PSI) due to it's conversion factors? (will post in UD forum also)
basically yes; at high altitude if you push 3psi of boost (going by the boost gauge that reads relative) you'll be slightly over 1 bar(ometric pressure unit or sea level)/1000mbar of pressure goign into the engine
06-10-2004, 09:58 PM
#6
1.5 BAR
Thread Starter
Join Date: Sep 2003
Posts: 660
Re:How the ECU reads Boost...MAP sensor Q
that makes sense. ------- altitude. I think i'm gonna take a reading from my MAP sensor using uberdata and try to write a scalar script to reflect the right Boost level (i.e. if at ambient the MAP reads 850 mbar, then tell uberdata to display anything >850 mBar as boost and convert to PSI)
Thanks!
Thanks!
Thread
Thread Starter
Forum
Replies
Last Post
robs99si
Forced Induction
13
09-13-2004 09:27 PM
robs99si
Engine Management
7
06-02-2004 06:55 PM
