I'm replacing the stock MAP sensor with the AEM 3.5bar unit.

It is a 3.5 bar absolute pressure sensor. That is, it reads from 0 (-14.7 psi gauge pressure) to 3.5bar (35.12 psi gauge). The stock MAP sensor reads from just above 0 (-13.9 psi gauge) to about 1.7bar (10.84 psi gauge) according to the AEM software.

I have some tuning in place with the stock MAP sensor. When I run the AEM Sensor wizard to tell it I have the AEM 3.5 bar sensor it re-scales the fuel map so the top line is 35.12psi rather than 10.84psi. Great.

But you would also expect all the learnt/input values to be in the bottom half of the table with some values interpolated. This is not the case. The top line (which now represents 35psi) is the same values as the top line of the old table (which represented 10psi). Not so great.

Am I doing something wrong or is this a limitation of the AEM? I realise I can do some calculations and approximate the new values (basically just enter ever second vertical value in the bottom half of the table) or just retune but I thought considering the very clever injector wizard that it would be a bit more helpful than this.

Also, by installing a sensor with twice the range have I effectively halved my sensitivity as the the table is spread out over a greater range? Can I add new points? And can I change the pressure value they represent? If I could I could make the bottom half of the table the same as the old table.

 

You need to highlite and copy the whole fuel map and paste it back to the portion 10.84 and below. Now you are going to have to retune for everything above 10.84.

 

But with the same number of breakpoints spread over twice the load that isn't directly possible is it?

 

Oh I see. It just interpolates the values according to the break points right? Nifty! Not sure why it doesn't do that during the conversion.