msd 3 bar map help

fearRSXenigma · Post by **fearRSXenigma** » Mon Mar 12, 2007 10:59 pm

i installed a msd 3 bar map sensor and after selecting it in kpro the car would start sputter and die. if i gave it some gas i could keep it started but datalog would show me running very lean. double checked all conections and they were good. I selected the neetronics 3bar setting in kpro and car started up no problems and it read boost fine.

Any one else have this problem are have any idea why I can't use the msd setting?

inglamos · Post by **inglamos** » Tue Mar 13, 2007 7:25 am

I just installed the msd sensor and the same thing happened to me. i haven't changed k-pro settiings yet, but i'll let you know what happens when I do.

inglamos · Post by **inglamos** » Tue Mar 13, 2007 1:29 pm

My car still wont start up. It sputters and dies. I'm wondering exactly whats wrong. Does anybody know how to do the custom map settings formula? I know that the MAP sends 4.85 volts to the ECU...

inglamos · Post by **inglamos** » Tue Mar 13, 2007 2:30 pm

Also, for the split second the car is on, it read 145 for MAP.....

Post by **Spunkster** » Tue Mar 13, 2007 2:54 pm

Check with MSD and see if htey have a new source for map sensor, because it sounds like they are not usign the same sensor that they used to.

inglamos · Post by **inglamos** » Tue Mar 13, 2007 3:52 pm

According to MSD everything is the same, they claim its the same as the GM sensor.

Post by **Spunkster** » Tue Mar 13, 2007 3:59 pm

Well there are at least 3 different types of GM sensors, so that could be part of your problem. This is also why we do not recommend the GM sensors. All you can do is use the formula for calculating the scalar and offset from the help file:

Here is how to calculate the scalar and offset for a MAP sensor.

1. Find the minimum and maximum voltage and absolute pressures.
2. Convert the pressures to mbar.
3. Subtract the minimum and maximum voltages to find the range, then do the same for the pressures.
4. Divide the pressure range by the voltage range to calculate the scalar.
5. Multiply the minimum voltage by the scalar to calculate the offset. Note that a positive voltage gives a negative offset.

Example for a 3.5 bar MAP sensor:

1. For a 3.5 bar data sheet:
0.5V @ 0 kPa (absolute)
4.5V @ 345 kPa (absolute)

2. 345 kPa = 3450 mbar.

3. Voltage range = 4.0V, pressure range = 3450 mbar.

4. 3450 / 4.0 = 862.5 = scalar

5. 862.5 x 0.5 x -1 = -431.25 = offset

So scalar = 862, offset = -431

Plug in the minimum and maximum voltages to check your work:
0.5V x 862.5 - 431.25 = 0 mbar @ 0.5v
4.5V x 862.5 - 431.25 = 3450 mbar @ 0.5v

If you have trouble then draw a graph and extrapolate the lines until they cross the pressure axis.

inglamos · Post by **inglamos** » Tue Mar 13, 2007 5:47 pm

I could do that, but how do i determine the min and max voltages?

inglamos · Post by **inglamos** » Tue Mar 13, 2007 6:23 pm

Clear security FTW.

after wiping the ecu the new map took with the neetronics 3 bar setup and started up fine. warmed up, came to steady idle, no problem.

Why did I have to wipe the ecu though? Bug in the new version?