MAP Sensor for MFI
 

For those of you that are logging MAP with MFI, how did you plumb the vacuum port? I know the 72- throttle bodies have a vacuum takeoff. I have a set of sporto throttle bodies with the ports, but they were plugged at the rebuild. I suppose I could drill a very small hole through the plug and use a barb fittting but would be curious as to what has been proven to work.

OK, I know nobody NEEDS to log MAP with MFI (unlike EFI). But I have all these extra channels in my data logger. . . need SOMETHING to keep me occupied. . . :)

John, I have not done this exercise with MFI but have done so with EFI. The challenge is getting a clean MAP signal while using ITBs and an aggressive cam. you will need to install a barb on each throat. These will all need to connect together in a ballast tank. I used a section of PVC pipe with end caps as my ballast tank. Back the center with foam to dampen the pulses. Then take a single line off the ballast tank to your MAP sensor for your datalogger.

Without the ballast tank you will get a very choppy signal that will be hard to correlate with throttle openings and such. MAP will change very quickly compared to other parameters.

Also you can jamb an old carb jet into the vacuum line to dampen the pulses, that along with the tank will give you a pretty steady vacuum reading.. We usually do something like that on ITB installs.

for the sensor all you need is a basic GM 1 bar MAP sensor. Ill have to check but the signal output is between 0-5 volts and is easily correlated to pressure. You may have to write a function for the logger to interpret the voltage directly to pressure......... easy peasy

I have a box full of jets from the good old days :cool: