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winker

08-31-2011 08:18 AM

Peak and Hold Software Solution

I think I may have come up with a software solution for Peak and hold injectors. I did some very quick tests at lunch time, and grabbed some scope traces, which look very promising.

This fix relies on the two inductive voltage spikes, one at injector on and one at injector off (the trick is to work out which is which).

After work I'll up date this post with the scope traces and my code mod fom people to have a look at and perhaps try out.

I dont have a mpguino (any body want to send me one for testing!), so loaded the code into an arduino and assigned one of the pins to show the injector pulse status.

I then attached my scope to the incoming signal and the pulse status pin. The traces look very good.

Regards, AJT

winker

08-31-2011 08:19 AM

Here is my modified code (pin 10 was setup to output the digitaly processed signal (i.e. the square wave)

It use the injector settle parameter to determine if it is seeing a start pulse (I have mine currently set to 80uS, which as you can see works quite well).

Code:

#define dspInjectorPin 10



boolean lookForOpenPulse = true;





void processInjOpen(void){      

  //20110831 AJT Peak and Hold ;)

  if(lookForOpenPulse){

    injHiStart = microSeconds();

    digitalWrite(dspInjectorPin,HIGH);  

  }

}      



void processInjClosed(void){

  //20110831 AJT Peak and Hold ;)

  long t =  microSeconds();

  long x =  elapsedMicroseconds(injHiStart, t);   

  if(x<parms[injectorSettleTimeIdx]){

    lookForOpenPulse=false;

  } 

  else {

    //    if(!lookForOpenPulse){

    tmpTrip.injHius += x;       

    tmpTrip.injPulses++;      

    if (tmpInstInjStart != nil) {

      tmpInstInjTot += x;     

      tmpInstInjCount++;

    } 

    else {

      tmpInstInjStart = t;

    }  

    tmpInstInjEnd = t;

    //    }

    lookForOpenPulse=true;

    digitalWrite(dspInjectorPin,LOW);  

  }

}



pinMode(dspInjectorPin,OUTPUT);

The following is a trace showing the injector input at the top, and the digitally processed signal (pin10) out. Looks good!

https://picasaweb.google.com/lh/phot...eat=directlink

and zoomed in (note small spike is injector opening and large spike is injector closing).

https://picasaweb.google.com/lh/phot...eat=directlink

and the following shows a close up at idle of my injector signal

https://picasaweb.google.com/lh/phot...eat=directlink

winker

09-01-2011 12:58 PM

1 Attachment(s)

For completness the following image shows traces for both sides of my injector (SPI), realtive to ground. The traces were recorded at different times, but you can see the relationship.

CrazyLee

09-08-2011 07:18 AM

Tried an LM339 comparator circuit

Thanks for the new thread.

I finally got to add the pictures about my comparator circuit. My LM339 comparator squared up the whole pulse, not just the two pulses that get wider as I rev up the motor-in gear w/ brakes on- to load the motor. I need a better circuit to get just the pulse width change.
pictures of the traces here.

1993 Fleetwood Flair

Thaks, Lee

Quote:

Originally Posted by winker (Post 259103)

For completness the following image shows traces for both sides of my injector (SPI), realtive to ground. The traces were recorded at different times, but you can see the relationship.

winker

09-08-2011 01:41 PM

I have today finished building my own MPGuino based on the these schematics

/trunk/mpguino/ - opengauge - Open Source Fuel Efficiency Instrumentation - Google Project Hosting (the 13 version)

I plugged it in and got no injector pulses though the VSS was working. After quite a bit of checking I realised that I had been here before. I needed to replace the 50K input resistor on the injector with a 1k. See my previous post

http://ecomodder.com/forum/showthrea...ers-11291.html

That sorted things, and is what I had on my test rig cobled together when I first tried to get this working. Im now going to switch the 50K VSS for a 1K (perhaps 1.2K what the hell).

winker

09-08-2011 01:47 PM

@CrazyLee: can't see your pics, infact on your page the only pics I can't see are the mpguino trace ones! Guess you may have moved or be in the process of updating them.

I tried the comparator route, but got nowhere fast, as the gap between the pulses became almost smaller than than the hold portion of the waveform. Thats when I went for the software solution.

I have set my detection pulse to 40uS (aka injector delay parameter), and this seems to work very well. I now need to house my unit, then calibrate it.

If you have access to a scope might be worth trying my software mod, and see what you get.

winker

09-08-2011 01:50 PM

@DCB:

thankyou for moving this thread.

CrazyLee

09-09-2011 10:45 PM

Got pictures back.

Hi, I found out this morning the photo's weren't loaded onto the server. I fixed that tonight. Comparing the traces for other P&H injectors they don't look like mine turned out. I got 50 MPG in my converter test. I think I know why. The mpguino may be reading the trace upside down! Looking at the small pulse gap between the actual first and last pulse. If I invert the signal it may read OK.
Nah! I still wouldn't get the actual pulse width. But it explains the 50 mpg reading.

I'll keep trying. I got the pre-built 'guino and I can't rebuild the code.

I may the Inj Delay to 1350us to see what happens there. It's at 500us now. I'm reading 13 mpg right now and 10.5 mpg is what I have been getting.

I really need to do a mpg run. I just filled up the tank. UGH! 70.119 gallons @ $3.509/gal= $225.00 I drove 60 miles w/ my 57 chevy in tow. The gauge shows about 5-7 gallons gone. about 8.5 mpg ( 5/5ths on my gauge. ) about 15 gallons per mark. 787 miles at 10.5 mpg. Hows that for hyper-mileing!

Cheers, Lee
================================================== ========
Thanks, Lee

Quote:

Originally Posted by winker (Post 260122)

winker

09-13-2011 02:43 PM

I've built my MPGuino, and installed it in the car. Topped up yesterday, and now just need to get some miles on the clock to calibrate it.

CrazyLee

09-14-2011 08:20 AM

mpguino calibration

Way to go! Be sure to note the fuel usage that appears unusual.

Calibrate your odometer on the expressway mile markers.

Follow the calculations to calibrate the mpguino.
Mpguino calibration - EcoModder

Have fun saving on fuel.

Cheers, Lee

Quote:

Originally Posted by winker (Post 260832)

I've built my MPGuino, and installed it in the car. Topped up yesterday, and now just need to get some miles on the clock to calibrate it.

winker

09-15-2011 08:14 AM

I have already started saving. Even during testing I could see I had a heavy right foot!

I've done 62 miles since filling up and the mpguin is 0.07miles under the car odometer. So not too bad, initial setting (already had an idea what the vss pulses were from my previous efforts a few years ago).

CrazyLee

10-19-2011 04:40 PM

I got the JayCar pulse & hold module

I looked at the JayCar module and it looked good the price is au $19.95 . The price was right and the shipping from Australia was only $10.00

I built the module from the parts provided. The kit was very well done. The manual was excellent and made the job very easy.
I recommend this module for anyone who has pulse and hold injectors. It makes no sense to try and build your own circuit!

This solves that pesky problem completely.

If you want a completely assembled module and I can put the kit together for you for the included cost of the module and labor for $45.00 plus shipping to you.

email me: mailto:lklemetti@comcast.net

Quote:

Originally Posted by CrazyLee (Post 260328)

dcb	10-19-2011 05:34 PM

Do you need an oscilloscope to dial in the jcar module?

CrazyLee

10-19-2011 10:51 PM

No you do not. I found that if you drove the vehicle a short distance (5 feet) the 'Guino would show a reading. If the V resistor was mis adjusted the signal out is a flat line and the 'Guino shows 999. Just adjust the pot until you see a display and move it a little more to be sure that it is stable.

I'm going on a trip this weekend and I'll report how it works. Right now I am happy with the results.

By the way, this kit is a dream to put together, well designed. It really makes sense to use it.

Cheers :)

Quote:

Originally Posted by dcb (Post 266323)

Do you need an oscilloscope to dial in the jcar module?

bestclimb

02-29-2012 02:49 PM

does the Jcar module work with the standard Mpguino code or will I need to rework the code?

CrazyLee

02-29-2012 08:24 PM

Calibrating an MPGuino with a JCar module

Quote:

Originally Posted by bestclimb (Post 290165)

does the Jcar module work with the standard Mpguino code or will I need to rework the code?

The Jcar module works with the MPGuino. I have found out that my settings needed changing. the micro-sec/gallon was way off from what I was using.

The regular calibrating method should work well.

To get close I set it very high (Mine went to 40,000,000 to start!) and watched the instant MPG. I kept bringing the micro-sec/gallon down close to what you think what the car MPG should get.

Having a passenger fiddle with the switches to reconfigure the micro-sec/gallon number is a great safety feature! Then you can do it on the run.

After that do an actual fill up calibration. This should only be a two run test if you are close to start with. Follow the instructions on the website.

I hate to burn up that expensive gas!

Tell us how it went.

consaka

04-05-2012 01:53 AM

@Crazylee, can you do a 328 conversion on an old 128 unit? Mine quit working way back and I was supposed to send it in but life got in the way. Someone knowledgeable with these things should be able to fix it and upgrade it. Oh and add a jaycar. What would be the cost?

CrazyLee

04-05-2012 08:07 AM

The jcar module costs $30.00 from Australia. You have to solder it together. I could do that for you at $60.00 total.

The 328 from a 128 unit wouldn't be possible. Just buy the better 'guino.

consaka

04-05-2012 10:45 AM

Hmm I been away a while, though my last visit to the old purchase page looked like they weren't being made anymore. Where can the newest versions be purchased?

CrazyLee

04-05-2012 11:12 PM

Where to get the jcar module

Hi, I had to look through my posts to get the URL for the Jcar module.

Here it is.

Peak Hold Injector Adaptor "Kit Back Catalogue" - Jaycar Electronics

Thanks for the interest. The Jcar pulse & hold module solves that problem.
It is designed very well and easy to assemble. The instructions are superb!
Just ohm the resistors to make you get the right one in the right place.

It takes about 2 weeks from when you order it to arrive at your place.

kep	06-19-2021 01:19 PM

Quote:

Originally Posted by winker (Post 259103)

For completness the following image shows traces for both sides of my injector (SPI), realtive to ground. The traces were recorded at different times, but you can see the relationship.

where to embed it in the code? what would work?

freebeard

06-19-2021 03:01 PM

Quote:

winker
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