m1bjr

I mentioned that I chopped my SG2 from the Honda into the R26 Renault some time ago to measure boost.

This is by far simpler and tidier than adding a boost gauge and pods etc in many cars.
One chap on here who I'm sure will repost his pics installed the SG2 into the radio door - very neat!

Anyhow, the comment provoked the question of how to make the SG2 read boost pressure on turbo cars.

You set up a virtual gauge on the display, they call these 'XGauges' IIRC.
Its using the MAP - Manifold Absolute pressure - reading from the ECU.
However, MAP is just that and the reading includes atmospheric pressure which depends on the weather but its reading will always be close to 1000 millibar (1BAR)
So, if you want to see the true boost pressure above atmospheric then you need to zero this number off the answer


And here is how to do it and read out boost in PSI:

1. ENGINE OFF - IGNITION AND SG2 ON
From the HOME screen use MORE>MORE>MORE>XGAUGE

2. Then in the top right select the number of the XGauge memory you want to use (0 to 24)

3. Next, Using the buttons next to + and - to select characters and the -> in the top right to move to the next character:
Enter 686AF1010B on the TXD screen and press OK>
Enter 0441850B0000 on the RXF screen and press OK>
Enter 2808 on the RXD screen and press OK>
Enter 00910064#### on the MTH screen and press OK> (Initially just type in FF71 where the 4 hash marks are)

4. You can look in the list below and try different hex codes in the field above to adjust the zero on the gauge.
If you really do know todays atmospheric pressure then pic the code below that equates to it


#### PSI
---- ----
FF8A 11.8
FF89 11.9
FF88 12.0
FF87 12.1
FF86 12.2
FF85 12.3
FF84 12.4
FF83 12.5
FF82 12.6
FF81 12.7
FF80 12.8
FF7F 12.9
FF7E 13.0
FF7D 13.1
FF7C 13.2
FF7B 13.3
FF7A 13.4
FF79 13.5
FF78 13.6
FF77 13.7
FF76 13.8
FF75 13.9
FF74 14.0
FF73 14.1
FF72 14.2
FF71 14.3
FF70 14.4
FF6F 14.5
FF6E 14.6
FF6D 14.7
FF6C 14.8
FF6B 14.9
FF6A 15.0

5. Enter "BST" or whatever name (3 characters max) you would like for the XGauge and press OK>
6. Press SAVE>
The MAP [engine off] reading on my Scangauge was 14.5. Using "FF6F" for the MTH screen value resulted in a BST reading of -0.2 so I had to use "FF71" to make it read 0.0.

Obviuosly this simple gauge wont auto adjust for atmospheric changes (if we ever get a summer)
So then daily pressure may be higher so your gauge will read a tiny value in PSI with the engine off, no biggie.


If you prefer your boost pressures in BAR:

Change the setup to this-

Codes are.
TXD 686AF1010B
RXF 0441850B0000
RXD 2808
MTH 000A0064FFF6 should be right to read 0.0bar, if not change the 6 till you get it to show 0.0



PS: These zero values are tuned by altering that four charecter code with ENGINE NOT RUNNING.
With the engine running and no boost (at idle) all manifold pressure MAP sensors will show a vacuum generally about -9psi or more.

The Loon

I haven't got a SG2 but this a very helpful post