With a single bar map sensor the PFC uses P01 - P09 for vacuum and P10 - P20 in approx 1.5psi steps from 0psi to 17psi.

ie
P10 0 - 1.5psi
P11 1.5 - 3psi
P12 3 - 4.5psi
etc.

How do the pressure cells get remapped when using a 3bar map sensor? If only P10 - P20 are used for boost that is quite a range of boost to handle per cell...ie 4psi per cell if you have to cover a 42psi range with only 10 cells.

K

 

A 3 bar map doesn't go to 42 psi it goes to about 30psi. One of those bars is vacuum, stock is a 2 bar.

I don't know this to be fact, but I would be totally surprised if it it didn't just scale the P-rows across the voltage of the sensor.

Wade

 

ahhh...that would make alot of sense...I'll post in a few weeks when I know for sure, I'll be installing a 3bar ... then will review some datalogit data and confirm.

k

 

Deja vu

The default mapping of p10 to p20 is:
0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.0, 1.2, 1.4 bar

But you will never get past P19 on a 2bar sensor.

Just changing to the 3bar sensor doesn't remap the cells - but will allow you to use P20.

 

Exactly ... 3bar sensor doesn't remap the PowerFC it only allows the user to remap the P values.

For example you could make p10 to p20
0.0 0.1 0.2 0.3 0.45 0.6 0.8 1.0 1.2 1.4 1.6
-or-
0.0 0.15 0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5

example one just makes a bigger spread @ 0.45 and increases overall boost to 1.6 where as example two increases boost to 1.5 yet makes each step smooth

to take full advantage of the 3 bar sensor p10 to p20 might look like the following:

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0

REMEMBER: if you remap the P scale then the data in the maps has to change!

 

spyfish, what setting do I use in the PIM when I change to the 3 bar. I am not sure which option to use, I have read different opions. I have a GM 3 bar but not installed. I think my stock map sensor in screwed, on the dyno I was getting a max peak of .74, my Greedy electric was showing 1.05 and we hooked up a maech boost and it was showing the same .75. Would this cause big problems with the motor misfiring? My dyno was really bad with big spikes, the guy thought I was detonating so We pulled out timing and it helped but they were still coming back in diff. spots. I am thinking thw map sensor is causing this or my coils.

Steve

 

Interesting stuff guys, thanks for the info. How does one go about changing the scale of the P-rows? Does this require datalogit?

Wade