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Simplest EFI setup 
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Hello, I have an old 4-cyl tractor-loader-backhoe (TLB) that I'm working on getting running properly.
I'm currently finishing up conversion of the ignition to a distributerless coil-on-plug setup,
which I will show when its finished. (well ok, here is a pic.. :)
(BTW, the megasquirt is way overpriced for what it is, I'm using my $10 micro)

But now I'm thinking of replacing the worn out carb with manual choke with an EFI system,
and I'm thinking of how simple can I make it? As a TLB, it isn't like a car, the engine is usually always loaded,
running the hydraulic pump and/or moving the vehicle.

My interest in EFI is that with the carb is pretty shot, throttle shaft is worn out. Replacements are available,
but why spend to get back to a poor system. It takes a long time to warm up before it runs properly,
using a manual choke seems quite primitive.

So how simple can I get to replace the carb? A TBI for sure, but can I just use a wide-band o2 sensor, and a MAF as inputs, or do I also need engine temp and air temp, etc. how simple can I make it?

thanks, jack


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Sun Oct 30, 2011 9:12 pm
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Hi Jack! Welcome along :-)

Sorry for the post activation thing... Three new posts today, two spam, and yours... I've changed your account to be normal now, so it won't happen to you again.

I got to bed at about 7am, so I won't reply, or even read in detail now. Time to sleep for a few more hours, more later!

EDIT: I lied. I read it. I'll move it to a more appropriate sub forum once you acknowledge this post and then reply.

Thanks!

Fred.

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Mon Oct 31, 2011 10:59 am
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Really dont have the experience to be answering your questions, sorry.

Quote:
I'm using my $10 micro

Wondering if you could please explain what you mean by this comment?

What will you be using for engine positioning, ie crank angle sensor?

Interesting project you have there.


Mon Oct 31, 2011 11:53 am
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oden wrote:
Really dont have the experience to be answering your questions, sorry.

Quote:
I'm using my $10 micro

Wondering if you could please explain what you mean by this comment?

What will you be using for engine positioning, ie crank angle sensor?

Interesting project you have there.


I'm using a MSP430 processor, I have a lot of them from a previous product I created.
But I see the boards are a little more expensive now, this one is $15,
http://www.sparkfun.com/products/57

I created a crank sensor using an aluminum disc with 8-1 magnets bolted to the crank pulley,
and a hall-effect sensor.


Mon Oct 31, 2011 5:28 pm
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Hello Fred, move it where it belongs...

Fred wrote:
Hi Jack! Welcome along :-)

Sorry for the post activation thing... Three new posts today, two spam, and yours... I've changed your account to be normal now, so it won't happen to you again.

I got to bed at about 7am, so I won't reply, or even read in detail now. Time to sleep for a few more hours, more later!

EDIT: I lied. I read it. I'll move it to a more appropriate sub forum once you acknowledge this post and then reply.

Thanks!

Fred.


Mon Oct 31, 2011 5:30 pm
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Done!

Now, back to your original post!

nimblemotors wrote:
I'm currently finishing up conversion of the ignition to a distributerless coil-on-plug setup,
which I will show when its finished. (well ok, here is a pic.. :)

Cool! :-)

Quote:
(BTW, the megasquirt is way overpriced for what it is, I'm using my $10 micro)

Agreed! MS2 chips are around 8usd or so, but they chose the variant poorly and the main boards are both badly designed and a poor fit for the needs of the majority IMO. The FreeEMS MCU/CPU is around 15usd for the chip, for what it's worth.

Quote:
But now I'm thinking of replacing the worn out carb with manual choke with an EFI system,
and I'm thinking of how simple can I make it? As a TLB, it isn't like a car, the engine is usually always loaded,
running the hydraulic pump and/or moving the vehicle.

The answer is "very". Especially on a single fixed application. A lot of the complexity and sophistication in FreeEMS is centered around working properly for nearly anything.

Quote:
It takes a long time to warm up before it runs properly, using a manual choke seems quite primitive.

I'm fond of manual chokes on cars, though you do need to understand the machine, and it seems a poor fit for a machine that doesn't have a driver focussing on it constantly. A temperature sensor and a simple lookup table should perform better in every way :-)

Quote:
So how simple can I get to replace the carb? A TBI for sure, but can I just use a wide-band o2 sensor, and a MAF as inputs, or do I also need engine temp and air temp, etc. how simple can I make it?

That depends upon how fuel efficient you want it to be, and how maintenance friendly. Running richer than you'd like will solve some of the issues that you'll face, but foul plugs and wash the bores down.

The wideband is only required for setup, once tuned you can take that and put it in a shelf or use it in another project. On boosted cars it's nice to keep a wideband on the dash, but if you go a little lean for a second it's very bad under those circumstances. On NA stuff, though, it's purely for show/interest. So you don't need the wideband long term. You should either fit a bung near the engine and put a plug in it later, or make a tail pipe fitting to stop clean air from screwing your readings due to reversion. In fact, re the wide band, the only reason you connect it to the ECU itself in terms of tuning usage is close correlation of the O2 data with the other parameters. For tuning it as is, you can likely just watch it and tweak values around until you're happy.

MAF would keep things simple, that's for sure, and likely eliminate or include the air temp sensor. In terms of MAF tuning, you just figure out the calibration of the device, then supply a desired lambda table and it should "just work".

Air temp you could add anyway to change ignition timing to be more optimal for varying conditions. But you don't need it if you use MAF. If you use MAP however, without running too rich, it's essential. Especially if you live in a place with proper seasons.

You're definitely going to want engine temperature. The fuel demand in a cold engine can be double, or triple or more. The only way you could dodge this, is, you guessed it, with a "choke" attached to a rich/lean pot :-) Which I think you said that you didn't like ;-)

In terms of code, it can be pretty straight forward too. You can do without any sort of transient enrichment due to the steady state nature of it. Worst case is a slight stumble if you change the throttle suddenly.

In terms of hardware, you can do without a warm up valve for airflow, but you'll either have to run a high idle, or manually keep it alive when cold, or pull timing out and make it inefficient at idle when warmed up. Idle can be set with the stopper on the throttle, though, other than that.

I hope that helps :-)

Fred.

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Mon Oct 31, 2011 11:51 pm
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What I was thinking is just a wide-band o2 sensor could be all I needed to adjust the fuel,
but they are not particularly inexpensive, and probably don't react fast enough.

OK, so I use a MAF, AirTemp, WaterTemp, and TPS, and o2 sensor, that should do it.
Next question is which parts to use? What TBI ?
The tractor has an updraft 1-bbl carb will say a GM 2-bbl TBI work upside down?
The engine is 159ci (2.5L), has a mechanical governer that moves the throttle arm to limit it to 2200rpm,
it is rated at I think 45hp. I have a couple Geo Metro 1.0L, and was thinking I could its TBI,
not sure it would work upside down.
What other parts/engines?
Junkyard is full of 10-15 year old cars and the pick-n-pull, I'm looking to do this about as cheap as I can,
but be reliable.


Wed Nov 02, 2011 5:48 am
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You don't really need TPS either, though it could help when the mech governor is doing things and like the temperatures, it's essentially free to have this in the micro.

The fuel supply issue of being upside down would only be an issue while starting, if that. It would be fine while running IMO.

I can't help you on the hardware side, really. But if you're planning to share your code I can review it from time to time, if you want. I highly recommend github for that, if you're going to.

Fred.

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DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Wed Nov 02, 2011 9:09 am
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Indeed, as my research continues, with a MAF, I don't need a TPS, and since this isn't a car that must accelerate quickly, don't need it. And it seems I don't even really need an o2 sensor.
A description of the Bosch Ljet just uses a MAF, air temp, water temp.
That sounds great, simple is better.

Research indicates that a GM TBI is the most common, one from a 4-cyl 2.5l or 2.8 v6.

So what remains is determine which MAF sensor to use?


Wed Nov 02, 2011 5:31 pm
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As I said above, you will want to use a wideband to set it up in the first place. After that, though, you don't need it. Without it, you're almost doing as badly as the old carby days, possibly worse as EFI, especially with custom code that's untested, has the ability to do wild extreme things that a physical carby that's roughly the right size and jetting simply can not do. Size the MAF to match the power for best accuracy and finesse of control. So, likely quite small for that engine with its poor flow, I guess. Choose carefully, though, MAFs can be pretty unreliable if not treated right.

Also, hot wire/film MAFs can't be used with K&N style oil based filters and are VERY sensitive to oil residue and FLAP meters have issues with not being horizontal, etc.

If you're taking TBI from an engine, and it's suitable, then the MAF is likely to be well matched too. If one also isn't, the other probably isn't.

Fred.

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DIYEFI.org - where Open Source means Open Source, and Free means Freedom
FreeEMS.org - the open source engine management system
FreeEMS dev diary and its comments thread and my turbo truck!
n00bs, do NOT PM or email tech questions! Use the forum!
The ever growing list of FreeEMS success stories!


Wed Nov 02, 2011 6:14 pm
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