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ECMlink Boostest vs map sensor

Posted by Sjd6795, Dec 20, 2020

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  1. Sjd6795

    Sjd6795 Proven Member

    Joined May 14, 2014
    Wilsonville, Oregon
    So I have done some reading and cant find an answer. Both my boost gauge and map sensor are showing around 15-17 psi at full boost, however the boostest calculated from the mas is reading 33. Why would this be showing basically double what my actual readings are? My first guess would be boost leaks but I fixed all of those and also just installed new fic 1220cc injectors and verified no leaks there. Afr at WOT is almost spot on. Getting 1.1 knock but its targeted 10.1 and I'm logging 10.4 so a little more fuel added will fix that.

    Street Build 737  13

    1997 Mitsubishi Eclipse GSX
    322 whp · 331 lb/ft · 2G DSM

    Street Build 1K  0

    1991 Eagle Talon TSi AWD
    manual · 1G DSM
  2. Stapl3

    Stapl3 Proven Member

    Joined Oct 27, 2004
    MI, Michigan
    Boostest is only accurate at peak VE, so ~5500rpm. Anything outside of that doesn't mean much and you should be focusing on your WB to AFRatioEST relationship instead. To get those to line up you're going to have to calibrate your fuel system by ignoring your 20 dollar analog pressure gauge, the numbers scribed on the side of your injectors, and rather look at those two logged values instead. There's too many variables with the fuel pressure gauge and the advertised injector flow rating to take them as gospel. Remember, they're ONLY numbers. #1 mistake is looking at the gauge, plugging in the global %, and going "yep, that's it" then doing outrageous stuff with the airflow to make it work. The real game here is to get the ECU to be correctly happy, so make it so. Use the tools you have, which in this case is a computer working in milliseconds paired with arguably the most accurate sensor in the car.

    The sign of a properly set up dsm and properly calibrated fuel system is having, specifically at ~5500rpm, WB=AFRatioEST and Boost=BoostEST and your mafcomp slider at zero or SD value at 100. If those 3 stars align, you're gold.

    Use this link to get you going from where you're at now. http://www.jeffgst.com/boostestcurve.html
    Last edited: Dec 23, 2020

    Street Build 2K  11

    1992 Eagle Talon TSi AWD
    awd · manual · 1G DSM

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