VersaTuner - tuning software for Mazdas
VersaTuner - tuning software for Mazdas
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Thread: 1975 Mazda REPU - Build and Repair thread

  1. #151
    No words bazooka joe's Avatar
    Donated: $40
    Miata & NEMOC Moderator

    2016 Miata Club, 2014 CX5 Touring, Honda 1976 XL 175

    Join Date
    Oct 2002
    wbee ma to NC 2016 Jinba ittai
    Quote Originally Posted by chuyler1 View Post
    Small update. I’ve been driving the truck a little more now that the roads are drying out. Lately it’s been a battle with the ECU not doing what I want it to and a lot of head scratching with regards to idle control. It would run fine in open loop but as soon as closed loop kicked in things got real bad. After more time than I’d like to admit I think I tracked the issue down to the following: I have no speed sensor, I have no clutch switch, and I have no neutral switch. That was putting the software in some odd state where it didn’t really want to let the car idle and it was throwing out whacky values for the idle air control valve, pretty much ignoring anything I tried to set.

    A speed sensor or neutral switch isn’t an easy task for an old truck, but I figured out a 1st gen RX7 clutch switch drops right in.

    I’ll need to put some more miles on it and play with the PID idle control settings but I think this will solve the stalling at stop signs. To get past the neutral switch issue I used the logic settings to make an assumption about neutral. If throttle is 0% and RPM is below 1200, assume transmission is in neutral regardless of clutch switch.

    All of a sudden the ECU started catching the falling RPM and changing gears was a little smoother. The battery died on my laptop before I could log a drive and fine tune things, but I’ll head out again this week as long as we don’t get more snow.

    [emoji849] wow, but I know you really enjoy this hunt!!! Don’t get the truck all salty!

  2. #152
    goes to eleven chuyler1's Avatar
    NEMOC & Rotary Moderator

    2013 CX-9

    Join Date
    Mar 2003
    Live Free or Die
    Well, my tune was good enough to get me to the top of Mount Washington, temps never went over 205.

  3. #153
    On my 14th Mazda. Matt22's Avatar

    90 RX7 Vert

    Join Date
    Mar 2008
    Eugene, Oregon
    I like rereading this thread to pick up on other stuff I need to get done to my truck.
    2015 Titanium Flash 3 SGT Hatch
    Tuned, Cat Back Exhaust, AutoExe Intake, Various bars, MS6 Wheels and Racing Beat Springs

    1977 Mazda Repu
    Racing Beat Header with custom exhaust, custom rust, and soon to have bucket seats.

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