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 Post subject: Re: A locost EFI
PostPosted: March 18, 2015, 8:36 am 
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TooBusy wrote:
I'd like to blow away the SU on the Mini


I too have had thoughts of blowing up the SU on my Mini.

TooBusy wrote:
convert the ignition to wasted spark.


I had the Ducellier distributor on my Mini, the only company lower in reliability than Lucas, and I'm sure it wasted most of the spark.

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 Post subject: Re: A locost EFI
PostPosted: March 18, 2015, 12:23 pm 
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Lonnie writes:
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I have the donor ECU and my plan is to have it installed for Phase I of my build. At the same time, I know it is concerned with many sensors and variables that will not be relevant to my Locost since they won't be there....
Does the board you show have storage space for storing you programs or is that held in some external device or extension to the board?


There is a pretty big push at the chip builders to get their systems down to basically one package. So that processor has space to store it's programs and calibration maps etc. It's similar in some respects to the computer that I ran for an engineering department at my first job. Except it's about 100 times faster and the other computer filled a drawer in a computer rack.

rx7locoast, the board I want to build would include the stuff you're talking about ( I think ). I would like a single board that includes the analog stuff, even the IGBT coil drivers. That will help keep the cost reasonable. It would be a single board but in the case of the high current stuff for the IGBTs at least and maybe the injector divers, they would have separate ground and power wiring to isolate them. So it's all one package physically, but it's really isolated logically.

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 Post subject: Re: A locost EFI
PostPosted: March 18, 2015, 12:54 pm 
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KB58, rusefi and rx7locost,

I'm looking at Schottky diode pairs to limit the inputs. I was up till 2AM last night and proud I picked ones recommended in the rusefi threads (BAT54 and some other similar). I also need to make sure my voltage regulator can sink current in addition to sourcing it.

The evaluation board has 10k resistors on the A/D inputs and that seems too high. So I need to check the leakage currents in the A/D and the clamp diodes and see if I can lower the value of that part. I think this processor has selectable gain for the A?D inputs of 1x, 2x and 4x. That may mean we don't need an preamp.

Some of the analog inputs probably require good accuracy. I haven't looked carefully yet, but maybe O2 sensors for example. So I will provide a good precision power supply part to supply the analog voltage and use a separate ground for the analog converter.

I think if we blow the fuse on the input of this board, the alternative is blowing out the whole board which would also leave you at a standstill. The issue is handling "load dumps" which are when the alternator finds it doesn't have a solid connection to the battery and there is no where for the power it's making to go, so the voltage spikes for a little while. They can each 60V or more. It seems they would need to be short spikes or everyone's headlights would get blown out, which I think you would notice.

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 Post subject: Re: A locost EFI
PostPosted: April 4, 2015, 4:09 pm 
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So I'm still plugging away on this. I have made some updates to the code and am happy to have my feet wet now so to speak.

One thing I have been curious about was comments I've read about injector "dead time" and how that can vary and require compensation to get even mixtures. I was able to get an injection setup from the friend who sold me my motor, it looks like older Mustang stuff that's been sitting on a shelf for 10 years. Perfect for getting up to speed.

One thing I was surprised at was the setup weighed in at 48.0 lbs. That's for the manifold and all the stuff connected to it, but not the large rubber air lines etc.

So i've managed to get a few of the injectors removed and measured. It basically took a big lever, but nothing seems to have really broken, maybe some little plastic cover on the tips of the injectors.

So let's get to the pictures. I was lucky and one of the first three injectors I pulled appears to be stuck inside. When I connect it up, there is no little clicking sound. With some work and practice I was able to setup my $130 USB scope to examine the signal used to drive the mosfet that is turning the injector off and on. I was hoping that the movement of the pintle in the injector would leave a signature, and was happy to find it!

Here are the three pictures. The first one shows the stuck injector which displays a nice smooth curve while the current is ramping up. In the next two pictures you can see a little dip in the curves about half up. That corresponds to the movement of the pintle which changes the inductance of the fuel injector which ten shows up in the trace as a pause in the rising curve.

The cool thin is that these two injectors clearly take a different amount of time to open. One of them opens after 1.5 mSec of time and the other at 1.7 mSec. I don't know yet how short pulses get, but if the pulse was not very long - during idling I imagine, this would make a bit of a difference.

Show and tell:


Attachments:
o5e_injector6.jpg
o5e_injector6.jpg [ 219.46 KiB | Viewed 2753 times ]
o5e_injector5.jpg
o5e_injector5.jpg [ 218.38 KiB | Viewed 2753 times ]
o5e_injector4.jpg
o5e_injector4.jpg [ 221.31 KiB | Viewed 2753 times ]

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 Post subject: Re: A locost EFI
PostPosted: April 4, 2015, 5:07 pm 
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horizenjob wrote:

The cool thin is that these two injectors clearly take a different amount of time to open. One of them opens after 1.5 mSec of time and the other at 1.7 mSec. I don't know yet how short pulses get, but if the pulse was not very long - during idling I imagine, this would make a bit of a difference.

Show and tell:


Both the opening and closing are important , if they dont shut properly the timed pulse is worthless so it may pay to send them of for cleaning and calibration. Its not expensive. I am also not sure if they behave the same way dry as they would if they were wet and up to pressure as they would be on a running engine , just thoughts.

Bob

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 Post subject: Re: A locost EFI
PostPosted: April 4, 2015, 8:41 pm 
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going to injection has another plus, you no longer need those 1=1/4" S.U. carbs but i do, i'm thinking of making throttle bodies from S.U.carbs without the float bowls.

this may require installing them backwards.

so please send all your old S.U. carbs to:-

john hennessy,
S.U. safe disposal dept.
p.o. box 325.
meadview.
AZ 86444

we can safely dispose of any and all S.U. carbs no matter what the size or quantity.

this is a free service to current S.U. owners converting to fuel injection, forum members and the general public.

hurry!!! this free offer may not last much longer, demand is high and we may have to return to our normal sircharge for disposal.

BUT WAIT,THERE'S MORE!!! for a short time, use the special code "skinner union" together with $5.00 additional shipping and handling charge, we will take a pair of S.U.s for the same price as a single.

carbs shipments containing linkage and installed on manifolds may be subject to an additional charge.

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 Post subject: Re: A locost EFI
PostPosted: April 4, 2015, 9:31 pm 
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Quote:
One thing I have been curious about was comments I've read about injector "dead time" and how that can vary and require compensation to get even mixtures.


FYI, They will also change with varying B+ voltages.

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 Post subject: Re: A locost EFI
PostPosted: April 5, 2015, 1:47 am 
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FYI, They will also change with varying B+ voltages.

I expect that. There's quite a difference from 14.5 volts running to whatever it droops to during cranking with the engine cold.

What I was looking for was individual differences between injectors. I don't know yet if that would vary by voltage but I'm guessing a slow injector is always slow. I suppose it could stop working entirely though at a low voltage before the other ones did.

It makes sense they might vary in how they close too, but I don't think I have any way to measure that electrically because it's after I turn it off.

It turns out 6 of the 8 injectors are stuck. I am glad I found 2 working ones in the first 3 I took off. I might have given up. I've tried squirting a little carb cleaner in but no results so far. I also tried 24V on one of the injectors and that didn't do it either. Maybe I need to soak them in some solvent, lacquer thinner?

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 Post subject: Re: A locost EFI
PostPosted: April 5, 2015, 4:05 am 
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I dont know the relevance of this vid but the guy that calbrated my injectors sent this https://www.youtube.com/watch?feature=p ... 5H_1m7MlMg
Thats quite a lot of fluid to stuff through a small nozzle and I would imagine if there was a build up of debris or varnish this would clear it.

Bob

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 Post subject: Re: A locost EFI
PostPosted: April 14, 2015, 4:16 pm 
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FYI on the EFI, here is another site with a lot of good information for the true do-it-yourselfer:
http://forum.diyefi.org/index.php

The goal on that site seems to be more along the lines of a full featured race-ready EFI rather than low cost, but still a lot of good information.

John

PS - Sorry this note is a bit late to the party, I just discovered the thread.


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 Post subject: Re: A locost EFI
PostPosted: April 15, 2015, 1:05 pm 
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the time laps on the opening and the effect that voltage has on the injector operation may not be a problem if you look at it from a different perspective.

rate of flow per pulse, if it opens late but flows the same, in the same period for the same signal pulse then there is no problem, it may close late or open further, its the flow that matters.

if the signal voltage degrades to 10volts to all the injectors equally, but the flow is irratic and not the same then you have an physical injector problem and not a voltage problem, if the voltage drops below 10volts do not expect anything to work properly.

below 10volts system draw to the whole engine is suspect.

although the internal ecu voltage may be 5 volts, the peripheries need 12volts and amps.

i am by no means an expert but i have been at the sharp end of fuel injection fault diagnosis, i have found that not much is critical as far as fuel delivery.

you could run a 65psi system at 45 psi without knowing there was a problem, a heated o2 sensor will just widen the pulse to deliver what is needed.( or what will do for now )

likewise, how strong the ignition spark is per cylinder is going to change the combustion in each cylinder with cop, thus effecting the o2 sensor signal that then adjusts the fuel overall so if you have a bad spark in one cylinder, causing a rich exhaust, all the pulse widths will be reduced to bring the overall back to 14.7 - 1 at the o2 sensor.

what i'm trying to say is there are so many variables with every cycle of the engine including temperature of individual cylinders, variances in cam lobe shape, oil pressure effects on hydraulic lifter variances all while the pulse width is an average from the o2 signal.

consider a multiple carb setup, to tune it you would "balance" the air flow to equal the amount of suck from each cylinder, what you in fact were doing was equalizing the vacuum signal on the jets so that a given quantity of fuel could be lifted out of all the jets at the same throttle opening which, due to the above and other factors affecting the vacuum signal would not normally be equal.

lately this "balance" has been carried forward to the temp of each exhaust runner as a means of balancing the burn in each cylinder as no matter how hard we try, they are just not equal as manufactured.

therefore if you insist on adjusting the pulse width of the injectors by an o2 device that only takes an average of all the cylinders, ask yourself, how critical is 1 to 1.5 milliseconds in an injector opening.

remember, the air charge is still vacuum based!!! and fully relyant on the inlet valve opening time, the overlap and the exhaust escaping velocity which, i guarentee it, will not be the same on any two cylinders.

Bob Lambeck makes his valves occupy exactly the same amount of space in the combustion chamber and the seats are exactly the same width.

i have gone off on a ramble again, but just remember, is the spark plug electrode orientation in the chamber directly related to the rate of and completeness of combustion as far as an o2 sensor system is conserned and consiquently the pulse width which is uniform to all cylinders? ( do you know which way your electrodes face? )

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 Post subject: Re: A locost EFI
PostPosted: April 16, 2015, 1:20 am 
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Sorry for slow updates. I am working hard on this and it's wearing me down a bit.

I did get all the injectors out of the manifold and rails and then I used some parts I've borrowed to try and clean them. I don't recommend what I did which involved open jars of solvents, dubious wiring, a fuel pump and holding the injectors into an aluminum adapter I had. I made it through once and didn't burn down my house. Next time I will try something safer.

Most of the injectors worked. Three of them occasionally dribble instead of spray, maybe about once every 10-15 seconds. That's with the proto ECU hardware running them at 1500 RPM. I think thy all show the same scope trace now. I haven't been able to tell if they give a different trace when they dribble as opposed to spray.

I want to get this right and I spent the entire day today trying to choose a capacitor for the power input to the unit. Sometimes there just aren't perfect choices. Trying to pick between parts with limited lifespans vs. ones that occasionally burst into flames. :rofl:

I have spent a little time on some other sites like the DIYEFI, but mostly just grinding on this board right now. I'm trying to choose a CPU chip in a package that can be upgraded to the next generation part. The newer part has a 4000 page manual. I'm too tired to actually roll around on the floor laughing so you'll have to imagine that!

John I hope the system will run well under 10 volts. I'm not sure about this yet. Up nawth heya, we hardly have any volts at all on the winter mornings. The auto industry has a lot of specs for these things. That's why I'm worrying about that cap, so the processor runs thru the cranking pulses in cold weather.

This hardware has provision for measuring the spark duration and also short circuits and open circuits and some temp limits for the injectors and coils. Not stuff I designed, it comes with the modern chips for these things...

So at least we don't make fuel corrections from the O2 sensor if a plug is not firing...

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 Post subject: Re: A locost EFI
PostPosted: April 16, 2015, 11:13 am 
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Marcus, you seem to have a "real world" understanding of the design parameters needed, not just abasic system that would need ideal circumstances to operate.

i remember some years ago we installed an engine management system in a circuit racer, the manufacturer specified that we shield anything generating interferance as it would cause it to shut down, which we did.

however, a particular car we raced against was always an also ran, when we over took him, our engine would missfire like a bitch, took a while to diagnose that one.

just remember the amp draw of everything else on the supply voltage with regard to wire size and fuse size.

local grounds and continuity back to the battery.

modern vehicles have a voltage sensing wire from the altenator to force the altenator to provide 12-1/2 volts to a piont in the wiring harness where the draw is highest and voltage drop may occure, this causes higher voltages in other parts of the harness less likely to suffer voltage drop.

sensing low voltage by this wire due to a fault is a major cause of boiling batteries, voltage stabilization is needed.

recently i have been experiencing wires in engine harnesses melting together, not bad enough to short but none the less you can't pull them apart without the insulation being damaged, this on various makes, the above is a potential reason but would be resolved by increasing the wire size over that required by the current draw, in a bundle, heat is generated and added to by the engine environment temp.

as far as the ignition, it must measure the KVA and do a comparison from cylinder to cylinder to find a spark fault that will cause a rich or lean condition, exceptionally high and the charge is weak, low and the charge is rich, pre ordained values within a particular range would probably surfice, these values may help on cold running enrichment when compared to engine temp.

i'm probably preaching to the converted here but just in case!

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 Post subject: Re: A locost EFI
PostPosted: April 17, 2015, 12:41 am 
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John, this is helpful stuff.

Quote:
recently i have been experiencing wires in engine harnesses melting together, not bad enough to short but none the less you can't pull them apart without the insulation being damaged, this on various makes, the above is a potential reason but would be resolved by increasing the wire size over that required by the current draw, in a bundle, heat is generated and added to by the engine environment temp.


I'm doing some looking at wire. Most wire has PVC insulation and it's rated to 105C. Another option is Teflon insulation. That's good for 200C, or 390F, also good to -55C, so our Canadian friends should like it too. Teflon is also chemical resistant. The good computer places I've worked at used it and I like it. It's a good step more difficult to strip and handle because it's slippery. I think that would also give abrasion resistance, but not sure.

It costs about 3 times the cheaper stuff. It doesn't seem like it would stick to itself or anything else for that matter.

Maybe it's worth it if people feel they are getting quality stuff when they handle it.

John could you measure some under hood temperatures for me in another month or two when it starts to get hot down where you are? Maybe I could send you something like one of those kitchen meat thermometers on a wire...

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 Post subject: Re: A locost EFI
PostPosted: April 17, 2015, 8:09 am 
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In the auto OEM world the under hood temp really depends on the location within the engine compartment. For belts we test life from -40° C to 150° C

Our experience on a number of different products is the two hottest places under the hood are the exhaust manifold and the catalytic converter. Those can routinely break 300°C under moderate load.

I'd think based on heat soak under the hood that I'd scale up wires a gauge before I went to Teflon coating.

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Last edited by TooBusy on April 17, 2015, 10:39 am, edited 1 time in total.

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