Engine bay tucking and re-organizing

Discussion in 'Suspension, Brakes, Wheels, and Tires' started by selttijcmanit, Apr 25, 2018.

  1. Nam1911a1

    Nam1911a1 Well-Known Member

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    A mechanical connect is ALWAYS necessary for reliable splices done correctly. If it was me I would just get insulated butt spliced and a crimp tool. It would be more effective than buying shrink wrap.
     
  2. selttijcmanit

    selttijcmanit Active Member

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    That harness looks amazing, yeah I love the adhesive shrink tube, takes a ton of force to pull out! You guys gotta stop flippn arguing lolol, obvi twisting and taping isn't for rocket surgery..

    I've nearly finished working on something you might all like, all goes well I'll post a tutorial. It's a super cheap megaSquirt that intercepts injection pulses and reads the map sensor to adjust AFRs for boost or whatever; and it has a nice little display!
    It uses the injector driver ICs from Honda ECUs :D

    Not only that but it has a potentiometer for on the fly tuning, and adds a percentage to the duty cycle so that it scales with the ECU (of course that can be adjusted in software).
     
  3. capsidx

    capsidx Well-Known Member

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    That’s actually hella clever. I’d buy one if I ever decided to go boost lol. Maybe when I have a spare motor I can look into that. Sounds like it would be good for na applications as well. Kind of like a substitute O2 sensor
     
  4. selttijcmanit

    selttijcmanit Active Member

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    Alright guys, not-so-little-update... Finished the injector hijacking thingy; thing is insanely cool, usually my electronics projects don't go well, but this one is pretty useful!

    It only took: an Arduino nano, L298N H-bridge, micro relay, lots of resistors, a capacitor, an iic display, a potentiometer, four diodes, two injector driver ICs from the old Honda ECU and a heck of a lot of programming and debugging.

    The Arduino reads pulses from the ECU to the injectors, but the ECU is still connected to the injectors via diodes; the injector drivers drive the injectors AFTER the diodes so the ECU can't tell the signal was hijacked. This way if the Arduino stops working, the car still runs perfectly normal (just without boost).
    Then, after intercepting the signals and calculating the time of the pulse, it uses a simple function to calculate how much longer the pulse should be based on the MAP sensor output. (For you nerds, the function is (sq(MapVolts) * .01) )<-- IIRC, not looking at the code RN

    This just means that the time it adds to the injector pulse is nonlinear, since my stock injectors need more fuel than usual. The map sensor wire is snipped before the ECU and a relay is put between the cut ends to intercept the signal to the ECU so it can't see the boost; it is a dual pole dual throw relay so I can attach an analog input to the NO side of the relay, when the relay is activated the ECU instead reads the analog output from the microcontroller which uses analogWrite() and the capacitor to generate a voltage which is the same as atmospheric. The MAP however is still connected to the Arduino so that it can change fueling accordingly, but the relay required too much current for the Arduino so I stuck an H-bridge on there.

    The display has graphs for MAP voltage, Duty cycle, and displays a graph for the Duty cycle that the ECU is outputting.. Super intuitive and also displays the real number equivalents for all those graphs. (The Arduino has plenty of spare time to drive a display)

    I'm sure some people will want to do this, so I'll try posting pics, schematics and a writeup soon, just kind of tough to draw out. I will say though, took it for a test drive today and had plenty of duty cycle left at 5psi on stock injectorbs, also, holy crap boost is amazing. This makes all the frick'n work worth every second!
     

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