DIY Fuel injection thread.

[Ned]

You certainly have the knowledge. Whats this Arduin sheild thing you talk of? Is it some sort of licensing thing or is it limitations created when using the arduino chips?

 

What are/is Micro? Is that geek talk for a type of processor chip that people use?

So micro is short for microcontroller, which is the processor. (sometimes can get referred to as uC to shorten it some more)

Arduino has lots of different boards with different micros on it depending on how many pins you need, or what size memory etc etc. The one used for speeduino is the biggest, baddest one they have. All of them, share the same arrangement for how the connectors come out of them, and you can plug in things called shields. A shield is just some extra hardware you can simply plug in, and sometimes even stack lots of them together. So if you want to add ethernet to an arduino, you plug in the ethernet shield. If you want to control some servo motors, you add in that correct shield etc. Speeduino is essentially just an engine management shield that you plug in to give it the hardware it needs to run an engine. Nice and easy for development, not very robust for real life applications.

People use arduinos for 2 reasons really. 1) arduinos have a very simplified coding overlay provided for them. So hobbyists dont need to learn an aweful lot about software and hardware because it's all standardised and simplified. You can just about say "turn on pin 1" and in the background it goes and figures out what pin is pin 1, find the correct register for that ports data direction pin, set it as an out put and then find the right register that controls the state of the pin and then set that high. It's like driving an auto vs a manual car kinda.

You dont have to use the simplified software, so people like me will use an arduino as a set of building blocks. I will get an arduino, find a shield with some bit of kit i want to use in a project and then i can just plug it in and evaluate my design, get testing etc and if i like it, i can go and build some dedicated hardware where everything is just on one board. This is what speeduino is kinda doing, but they arent making the leap to dedicated hardware yet and i'm not 100% sure why they havent yet. They might have a good reason i havent found yet.

[Bangbug]

Economy is a bugger.

Dyno's are your friend but I haven't got near one yet, waiting till the turbo, which I've been super slack about.

 

I've got a "lean cruise" function on the lunk.

I think I picked about 16.5:1 and it works at set manifold/tp %'s and a delay before starting up of 2 seconds or something.
I fecked about with it a little until I could see it start working and nothing changed, no noticeable drop in torque/speed and my throttle position was the same.

So same speed with less fuel = economy I guess.

With no knock detection I didn't touch the timing tables and they're all "safe".

 

I think on a dyno you can do these things and feck about with ratio until you see a drop off in torque, and then do it with timing as well

[Roman]

Ran some OBD2 logging on the Echo at lunchtime, confirms my thoughts that the 35/40 degree range seems best for cruising rpm 

 

(Although bearing in mind, my car cruises at 3000-3500rpm so will be different if lower cruising rpm)

 

Ignition advance up the side and rpm along the bottom

 

The bit at the end with timing decreasing was where I put the foot down to go up a hill a bit.

 

 

[Yowzer]

My table...

Yeah mate you should have a tonne more timing in there. The Fiat engine I did awhile back was somewhere in the 30s by 3k at full doort

[Yowzer]

Mash the timing right back on overrun so it pops and crackles and hopefully shoots flames

[Ned]

i'm sure the ones that care are actually on the speeduino forum, but the man did some actual tests on timing accuracy (on the bench) and here are the results, they are pretty good (for a low burget DIY EMS) and a lot better than most documentation on the web makes it out to be (which is where my initial info came from)

http://speeduino.com/forum/viewtopic.php?f=5&t=223&p=2955#p2955

[yoeddynz]

So micro is short ..... 'wall of very useful intersting text that learned me heaps'................... i havent found yet.

 

Awesome Ned. Thanks for that. Well written and good laymans terms

 

The main processor chip within the mega 2560 board- how much would one of those cost by itself. I am guessing at a cents value. If people can buy complete boards for $7 etc!!!

 

So once the lot is established to work well enough then a single board could be pieced together with all the right bits sourced by the builder for not many pingas at all. Although that arduino mega 2560 board is so cheap and can do the job then it makes sense to just use that avoiding a lot of soldering.

[yoeddynz]

Yeah mate you should have a tonne more timing in there. The Fiat engine I did awhile back was somewhere in the 30s by 3k at full doort

Where would you bump it up. Im looking at the area from above 60 kpa and 2300 rpm beyond which all looks a bit low. I had made that a bit lower further down the revs when I was chasing the low speed rumble thingee.  I think I can bump it up given I have worked out the rumble is from a very long propshaft that has been badly welded and balanced (by the professionals) and could do with being two piece anyway.

 

so maybe I bump that area up. My car cruises at 100kph around 3200 rpm.

 

Man- I so want some sort of economy meter thing. Hannah and I were trying to work out how it could be done using speed/distance from the electronic speedo pip and info of how long the injectors are open for fuel usage, then export info to RomanDave spec table generator program.

 

how do factory fuel economy meters work?

[Ned]

so the funny thing about china, is that they get mega mega good pricing because they make a zillion of 1 product.

Meet digikey. This is where a very large portion of hobbyists and professionals get their parts from. Once you get into big volume manufacturing, you would go directly to the manufacturer of each part, but if you have a product that you're making a few hundred or even thousand of, you would buy your stuff from digikey.

and this is the digikey link to the micro on that board

https://www.digikey.co.nz/product-detail/en/ATMEGA2560-16AU/ATMEGA2560-16AU-ND/735455

spoiler, it's $30 NZ and you can buy a whole arduino for $12

china will sell you the bare chip as well though, $25US for 5 of them, so still $8NZ each

http://www.aliexpress.com/item/Free-Shipping-5pcs-lot-ATMEGA2560-16AU-ATMEGA2560-MEGA2560-TQFP-100-IC/1927760663.html?spm=2114.01020208.3.31.jZFqGP&ws_ab_test=searchweb201556_2_71_72_73_74_75,searchweb201527_4,searchweb201560_9

It's crazy at how cheap they churn those out. If you were to make them in NZ (or any other place in the world that isnt china) then just the cost of putting the components on the PCB would be more than what china sells the whole thing for. And thats not even buying the bare PCBs or the parts for the board. Thats just the cost for a machine to place them on the PCB and solder them on. It's crazy how they can do it, it really is...

[Roman]

 

Man- I so want some sort of economy meter thing. Hannah and I were trying to work out how it could be done using speed/distance from the electronic speedo pip and info of how long the injectors are open for fuel usage, then export info to RomanDave spec table generator program.

 

how do factory fuel economy meters work?

 

Do you know the dead time for your injectors?

 

As you need to monitor effective duty cycle, and accurately know the CC rating of the injectors at the fuel pressure you're running.

Not sure how to figure out injector dead time if there isnt a spec sheet available for your particular injector, but that's the first thing you need to know.

 

Either way, it's good to have injector dead time entered into the ECU because it makes compensations more accurate.

 

[yoeddynz]

Its because they use very smart cats and dogs!

Edit; that was for neds pondering how china does it.

 

Nah.. i dont know my dead time. Could one not say splice into the injector power up feed and measure how long the current is being applied per sec.

 

The way I figure on checking actual ccs would be that you have a system running and you use it for a full tank. Take the mean average mpg figure that the program spat out and then compare to actual mpg you measured from re-filling the tank. Adjust program/settings to suit. Once you have done that a couple of times you would have it pretty accurate yeah?

[Roman]

Yeah if you want to get "a number" and arent hung up on the actual units.

 

Then you could datalog a trip.

 

Average all of your speed data points to get an average speed

 

average all of your injector duty cycle points to get an average injector duty cycle

 

Then lets say you had an average of 68kph / 15% duty cycle

Then second trip you had an average of 75kph and 17% duty cycle

65 / 15 = 4.3km per 1%

75 / 17 = 4.4km per 1%

So the second trip was more economical. So yeah you could tie that back to how many litres you're getting from a tank, and work out a rough value for what 1% injector duty cycle is worth.

But not knowing the injector deadtime means that it will over-report low injector duty cycles and under-report high duty cycles.

But you could get something that would give you a really good indication on which driving style nets the best economy, as well as measuring changes to fuel/ignition/etc.

 

[yoeddynz]

Injector dead time- does only really effect the idle? Found this article on working out your exact deadtime. Seems like a lot of pissing about though..

 

www.dsmtuners.com/threads/injectorc-dead-times-getting-them-right-instead-of-using-other-peoples-numbers.418584/

 

I reckon would get a pretty good idea on the right numbers  after a few tank fills and comparisons. Im sort of keen on having a fairly accurate 'gauge' of economy. It will be just that.. a gauge. Once I know that say a reading of 27 mpg is actually within 5% of actual mpg then thats pretty good. Then I have a gauge I can go from and strive to find the best driving form that increases my mpg.

 

(this all goes out the window once I find a nice hilly road.. but hey..money saved whilst driving on boring roads is money to be burnt on great roads!!!)

[yoeddynz]

Oh Dave... this guy has done some graphs. You'll like it...

 

[yoeddynz]

Yes!!!!  This...

 

http://ecomodder.com/wiki/index.php/MPGuino

[Roman]

Yes!!!!  This...

 

http://ecomodder.com/wiki/index.php/MPGuino

^^Awesome!

I've been mucking around a bit with fuel stuff, equations are a pain in the balls because there's a lot of unit conversions required, and I need to apply them to log files.

So I tried using a table for a spare PWM output, where one axis is Effective Pulse width and the other is speed. Then I fill out the values in the table, which is a number which does nothing but is the exact number for litres per 100km

First problem with this, is that the PWM values can only go to 100 so half the table was maxxed out. Bugger.

Second problem is that datalogging doesnt show me the actual PWM % value anywhere, so I couldnt setup a gauge or whatever to show me the realtime number. Bugger.

So went down a different avenue, I remembered that I can have a "traditional" fuel model or a "modelled" fuel model.

Modelled takes into account engine size, injector size, fuel pressure etc to calculate fuel. The advantage of this is that it can now output a value in CC per min that it can show me in realtime.

Which still isnt quite what I want, but a lot easier than any other options.

 

Easy calc from there to get L per 100km, but a pity I cant see it in realtime.

 

If I setup the CAN/BUS I can output to an OBD2 port, and then use the program Torque on Android to calculate all of the other values that I want.

 

Buuuuuutttt stink thing is that if I have can/bus connected, I lose the ability to datalog to the laptop. As the internal circuitry can run one or the other, at once. Bugger!

 

[yoeddynz]

Have you got a electronic speedo too ?  Yeah Im quite excited about that MPguino thingee. Even if its not super accurate first time round it can be tweaked and then so long as its consistent. 

 

Oh wow- i can start having a dash thats as lit up as something Ben would build!

[Roman]

Yeah I've got the Speedo drive in gearbox inputting to the ECU, and then the ECU outputting a PWM to drive the speedo on the dash.

 

I originally started out with a cable drive speedo, but it was so horribly inaccurate I needed a better solution to pass cert.

 

So got the guts from a later model speedo plonked into the old dash.

Made it much easier to keep an accurate speedo!

 

You'll need some sort of speed sensor for your economy gauge, but it's easy enough to fit a wheel speed sensor from a car with ABS so that it's measuring the driveshaft bolts or something like that.

[yoeddynz]

Oh I joined the electronic speedo club a while back. Mine will be the same toyota unit as yours as I nicked it froma celica, using the toyota speedo. Mine reads exactly 10% too fast which I have to take into account when checking fuel usage. Jaycar used to sell a little box of electrickery that you could adjust the pip signal from the sender to the head.

 

So I have everything I need.. just might order a MPGuino kit to build !

[Roman]

I got my knock sensor mounted properly so set it up.

Interesting results so far. 

 

It looks as though I can advance the timing at cruising right up to the 45-50 degree mark if I want, before it starts knocking.

 

I'm glad I waited and got the knock sensing setup though. 

Because with the reccomended ignition settings I was given for a beams motor, it was actually knocking through some parts of the RPM range at full throttle. (my engine has slightly different cams/compression to an Altezza beams motor)

And I couldnt hear it happening from the cabin or feel the difference in any way. So it's snipped a degree or two out here and there which is cool.

 

Interestingly though, I can now recognise by the exhaust note when the ignition timing is too far retarded. Sounds really rough, maybe because there's still some energy left in the gas when coming out the exhaust?

When I start advancing the timing and the engine sounds way smoother and a fair bit quieter too. Not what I was expecting.