Interest in a module to correct MPG gauge and OBC MPG?

[matt]

We were actually talking about this last week.

No progress... too busy with a million other things. I will see if I can't move this forward a bit next week.

[stormspike]

anything yet? I was about to start the S52 swap after the car gets back with the mtech2 kit. This sounds great!

[Roadsterd]

Progress?

[hoveringuy]

I want to do it as well but won't have time to devote to it until after April 11th. First thing I'll do is put an O-silly scope on the fuel signal to see what the waveform looks like and then figure out how to modify it, probably a PIC controller.

Anybody have data on what the waveform looks like? That would help.

[BeirBrennerE30]

PIC?!?! Why not AVR?

just messin with you... its one of those eternal debates

[matt]

You don't need a pic controller. It can be done with a very simple circuit.

I hope you guys understand why I can't help... we'll have something shortly, hopefully by the summer.

[etxxz]

what happens if you just add a resistor...i don't know what the input of the gage is, but couln't you just cut it a bit over half and get about the mileage that we want. my car averages 47mpg but i've beasured betweeen 23-24mpg hwy/city combined.

my understanding of electronics is just basic but i understand how these things work/read like voltimeters...but i'm sure that you know that.

[Rev Engineer]

It's a PWM signal of injector on-time. I was going to take a shot at modifying the software in my 6->4cyl tach converter, but the way I structured that software doesn't lend itself to an easy change. The PWM signal will go to 0% during off-throttle deceleration, I'm not sure if it ever goes 100% on - I don't think it does.

If anyone here is familiar with writing code for the AVR, we might be able to work something out. Or, maybe I'll find some time this summer to work on it again. My hardware will do it, it's just a matter of writing the software routines. Or, we can just wait for Matt to come out with his converter.

I like PIC's too, but happen to have a lot of spare ATmegas on-hand.

[BeirBrennerE30]

I can write the AVR code.... i just need the data and what chip you are using

[hoveringuy]

As promised, I finally had time to connect the 'scope to find the fuel signal waveform. Attached is a picture. It's a 12Hz signal, normal state is 13.5volts and it goes to ground for 1.2 milliseconds at idle.

As expected, the pulse width gets wider under load.

I'll start working on a PIC design now.

[dude8383]

Interested to see the finished product.

[hoveringuy]

Interested to see the finished product.

yeah... me too!

[sefb222]

if this happens, count me in for one.. please.

[dougsic]

Me too.

[hoveringuy]

It works!

It's not really pretty at this point on the bread board, but the point is that everything works. The PIC, the code, input/output and most importantly the trim pot to adjust the level of compensation.

I need a few more days to tweak the code (it's taking more adjustment than I anticipated) and I should have a few prototypes out in the field for evaluation in May. My goal is to make it suitable across a range of engines and injectors so it will be a one size fits all product.

Final size will be on the order of 1 7/8 x 1 1/4 x 7/8.

More to follow.