Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 7 of 7 Posts

·
Registered
Joined
·
14,305 Posts
Discussion Starter · #1 ·
At some point I intend to fit a 3 bar MAP sensor to my 9k to enable mapping above 1.54 bar .

Anyway in preparation for this I have today taken some readings and plotted some graphs:



Not a problem per se, 'cos I won't be want more than about 1.8bar. But it does seem like I've been sent the wrong sensor.


Now, all I have to do is work out how to get this mapped into my ECU...
 

·
Registered
Joined
·
53 Posts
Hi Bubbles, I think you have been sent the right sensor. The reason i think this is because a MAP sensor measures vacuum as well as pressure, so 2.2 + 0.9 is 3.1 by my calculations. I think this sounds about right.
 

·
Registered
Joined
·
8,948 Posts


You even said that you wanted to go beyond 1.54 bar boost that the standard 2.5 bar mape sensor provides.....

Andrew
 

·
Registered
Joined
·
52 Posts
My OEM Mapsensor is faulty. Is it OK to change to the 3 bar one without making any other changes. I know that there will be no benefit without re-mapping the ECU to recognise it but wondered if it would run as normal.
 

·
Registered
Joined
·
8,216 Posts
I expect it will throw the air/fuel ratio out completely. From the above graphs, the ECU will have to know you have a 3.0 bar MAP sensor fitted to the car, otherwise it will not interpret the signal correctly. For example, when the pressure is 0.5 bar, the 3 bar sensor will output 2.25V. The ECU, calibrated for a 2.5 bar sensor, will interpret that voltage as 0.3 bar manifold pressure, because that is the manifold pressure that will cause a 2.5 bar MAP sensor to output 2.25V.

Remember that a Trionic 9000 has no air-mass meter so the air-mass is calculated from other parameters, of which the manifold absolute pressure is a very important part.
 

·
Registered
Joined
·
52 Posts
Thanks for the explanation Bill, I understand it now and the graphs help. I'll save the 3 bar for another day.
 
1 - 7 of 7 Posts
Top