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Thread: Retrofit PWM to Throttle

  1. #11
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    Aug 2008
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    Dallas, TX
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    Post

    Well, for me, I just use an OpenPort 2.0 to put a custom tune on. Pretty easy since its a Subaru.. As far as ECU tech is concerned now is a great time to get open source hardware such as Raspberry Pi and others to take care of everything else such as sensor tweaking and PWM. You would want to have your ECU chipped for most makes. My previous Subaru yielded reasonable gains and better in-town drivability with what I would consider a sub-par HOD system mounted in the trunk WITHOUT modifying the OTS Stage 2 maps. What worked best? Resetting the ECU after the install and following ECU quick learning procedure after the car was at normal operating temps >=180 F. And no, there is no standard procedure across the makes. Each make has its own procedure and I imagine each procedure could very well yield different results.

    There is not an off the shelf hardware/software combo for sale that I know of. I can assure you that the hardware and programming languages to build such a unit indeed is. Takes time, dedication and know-how.. We are all tweakers here when it comes to building and exploring this technology.

  2. #12
    Join Date
    Apr 2012
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    127
    I imagined you could do something similar with a chipped obd1 ecu from honda. Like how I can use different free programs to reprogram the fuel map for a p28 ecu that will work with my obd2 f22b1 engine. Thats more used for performance but can be tweaked for hho.

    Free software and $100 to buy an already chipped ecu and writable chip.

  3. #13
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    Hondata? I looked into that mod for my Civic a few years ago. Definitely helpful for re-mapping.

    You would need pin outs to be able to send analog signals to the microcontroller unit in order to control the PWM duty cycle for HOD though. Not sure if that is an upgrade option.. I know that AEM offers that, but their ECU's are über expensive.

  4. #14
    Join Date
    Apr 2012
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    127
    Yeah. AEM ecus run about $1500. But I'm not quite talking about hondata as you specify to hondata and they rewrite the fuel map for you. Or reflash the ecu in the k series honda engines.

    What you can do with hondas is take a stock ECU from their obdI cars and use it with a compatible OBDII car (if you need it for OBDII), or just use the ECU in the OBDI honda. My 97 accord can use an integra/civic p28 ecu. They sell such ECUs altered with removable chips that can be written on using fuel mapping software.

    You can also pick up the stock ecu at a junkyard, solder a chipping kit on and do it all yourself.

    With this method, I think 90s Hondas would at least be the easiest to modify for hho anyways.

  5. #15
    Join Date
    Feb 2013
    Location
    Portland, Or
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    1

    Linking hho production to demand

    Would using simple RPM measurement make any sense? At least under more constant throttle settings you would know how much volume per unit time is needed to fill the cylinders and could try metering an appropriate amount of HHO to match? I've also been thinking about this but have an older carburated motor.

  6. #16
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    Yep, you could use the analog voltage signal as an analog input to drive the PWM input.

  7. #17
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    Apr 2012
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    On the accords there is a point in the harness where you can hook a tachometer up to. That could used. But that doesnt accommodate for engine load. It is a start though.

    I guess it depends on the most efficient mix of HHO.
    Is it best as a ratio to fuel intake? Air intake? Engine speed? Or even the amount of fuel burned measured by o2 sensors?

  8. #18
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    I think RPM would be best unless you have a really crazy fast hydrogen generator. Most generators won't respond fast enough to provide a really accurate ratio. It is, however, a lot better than running the reactor 100% the entire time. At idle the reactor should be producing nothing. My complicated setup will have the benefit of integrated LCD as well as logging so I don't mind the extra wait time and preparation. If you don't care about those things then you can avoid the hassle.

    You would just need a micro controller to accept the 12V analog signal from the tach port and output digital PWM 0/5V signal to the power module. Any Arduino can do this very easily.

  9. #19
    Join Date
    Nov 2009
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    1,418
    Most generators won't respond fast enough to provide a really accurate ratio.
    Stevo is 100% correct about not being fast enough to get the ratio 100% accurate over 100% range of the engine. This is the problem using the MAP or MAF signal which are all over the place and change to fast. They are still the most accurate and with the proper electronics can be used. I think in small engines you need to look very seriously at the torque curve and have max HHO at max torque. Off at idle, closed throttle, or just above idle. Divide the remaining up into 2 or 3 zones and you will see great results if you have the ratio right in each. This can all be done very simply using an adjustable vacuum switch or pressure switch if turbo charged. Cheap and easy. You will need to use solenoid valves to keep the pressure in the various zones when off which helps limit the lag time when they come on and off in the different zones. The pressure is very little more than is there all the time so is safe. This requires multiple reactors and/or pwm's so one reactor can be run in two separate zones. The smaller amount off the pwm and the larger amount off electrolyte concentration based on vacuum or pressure. This will cut down the number of reactors. This has proven to be the most cost effective method for me. I am still working on a controller to achieve this in one device though. Some serious dyno time is going to be required.

    WHEN YOU USE SOLENOID VALUES THE REACTOR MUST BE WIRED SO IT CAN NOT COME ON WHEN CLOSED!!!
    "Democracy is two wolves and a lamb deciding what to have for dinner. Liberty is a well-armed lamb."

    ONE Liter per minute per 10 amps which just isn't possible Ha Ha .

  10. #20
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    Aug 2008
    Location
    Dallas, TX
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    Solenoids are a great idea. Really easy to activate via the controller too. Torque curve on my turbo boxer motor can be read from the OBDII data so that should be easy. I will probably experiment with the algorithm A bit after the first install. Still waiting on electronics to arrive from China..

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