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Old 01-07-2016, 08:50 AM   #11
E30 Mastermind
Join Date: Dec 2005
Location: 42' Container, Woodland Hills, CA
Posts: 1,905
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About the econometer: Econometer funtions on PWM. What I've come to conclude is that BMW likes to take the injector pulsewidth and do some sort of conversion with wheel/vehicle speed. The cluster obviously receives its own VSS input signal and requires injector cylinder 1's pwm signal to calculate and display what the MPG is. Check attached "genericpwma.png". Note this is running on an completely stock M50NV running MS3X, but it shouldn't be any different for an m42 or m20 car.

Now I tried to make it a boost gauge, but the gauge contains the VSS input, which is hardwired into the econogauge. This causes a problem because boost has nothing to do with VSS, and making math in tunerstudio to negate a variable that isn't related is a nightmare. I want to know more about this, because I really want to make the econogauge a boost gauge or a A/F gauge, but I'm not going to go any further into it until I start getting into cluster mods. It's on my list of things to do, but its priority is pretty low.

The pdf is the pinout for the e30 m42. It's where I start for building PnP units.

Attached Images
File Type: pdf 1991 318i 318is.pdf (479.6 KB, 236 views)
File Type: png genericpwma.png (41.6 KB, 222 views)
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