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By 100percentjake
#52677
Howdy all. Thought I'd start a thread here to hopefully document my progress and get some help with a project I've just finished (?) collecting parts for: converting my 1997 Ducati 900SS to fuel injection using a Speeduino setup.

The meat and potatoes is that I'm wanting to create a fuel-only system in the style of a Holley Sniper EFI or FiTech, wherein the carbs are replaced with throttle bodies, the fuel pump is upgraded, and a crappy factory crank signal is supplied to the computer. No/minimal modification to the engine required, spark will remain handled by the factory means (which are trash, but whatever).

The layout of the machine is a 90 degree L-twin with two VR sensors triggering two spark controllers that batch fire the two spark plugs. The spark computers simply trigger the spark every time a leading edge hits one of the VR sensors (it actually switches between leading edge and trailing edge depending on the RPM to attain the world's most rudimentary spark advance). The "trigger wheel" has a single trigger. My thought was hooking the Speeduino in parallel with a jumper harness (it uses simple two-pin Honda-style connectors which I have plenty), plopping in a VR conditioner, and then... doing something. These fuel-only setups don't appear to be super common so finding other people who have documented using these hacky OEM setups. Concerns have been levied about batch firing the injectors causing cylinder wash. I'm not sure if that would be a concern or not. I'm not even certain for sure if this is a supported configuration (wheel with 1 trigger, two VR sensors 90 degrees apart, sequential fire via some sort of cranking algorithm?).

The goal is to have a fairly basic Alpha-N setup with the built-in MAP sensors providing a baro skew for various altitudes/ambient barometric pressure. Eventually I'd like to have closed-loop cruising using a wideband O2 sensor installed in the exhaust (I don't count this as "modifying the bike" because I'd do this if I stayed with carbs anyways), potentially with fuel trimming functionality similar to most modern cars to account for variances in fuel. I also want it to be fully reversible with no modifications to the bike or its wiring, plugged in entirely using jumper harnesses.
PXL_20210814_000510334.jpg
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Currently the bike has some garbage constant-velocity Mikunis which seem to be an exercise in "how complicated can we make a carbeurator?" and generally work ok some of the time maybe if they feel like it but I don't ride this bike very often and I'm bored so here we are.

Intake manifolds, fuel pump, and throttle bodies were sourced from a 1999+ factory fuel-injected Ducati, which differed in that it had an actual trigger wheel in the engine for more precise spark and fueling. It did operate on an Alpha N principle and I believe it batch fired the injectors as well. By all accounts it was pretty damn primitive.

Current questions:

Can I simply hook up the Speeduino to the VR sensors in "parallel" with the CDI boxes?
Injectors are ground-triggered, right? 12v-injector-speeduino? Most diagrams show it that way but it seems to be one of those things it's assumed you already understand. I've done a bunch of tuning turbo Miatas on Megasquirt via TunerStudio but "from scratch" like this has me struggling to comprehend the basics.
Is my injector trigger strategy viable?
By theonewithin
#52679
Your post is huge. So huge I didn't bother reading it all as it just goes on and on...

Right off the bat though your idea using VR conditioner for the existing VR sensors won't work. You can't share the VR signal.

You would be better off taking a signal from ignition system.

If you could condense your post down to just what matters and not a big story that would be nice
User avatar
By Chris Wolfson
#52682
Hi,
a Ducati is a very refined machine. There is nothing "crappy" about it. If the factory carbs do not work, let some one who does Ducati for a living, fix them. Don't expect such an engine to run with the cheapest fuel you can buy, that has been in the tank for month. That might be the cause for the different problems you have sometimes. It is no Briggs & Stratton lawn mower! Also, have it serviced and use not your Pop's favorite truck oil, but the fully synthetic stuff Ducati tells you. They do not make recommendations to make money, but to keep the engine alive. Ah, yes, oil has to be changed on these engines, even if you hardly use them. They are NOT made in Detroit / Michigan and run 50.000 miles or 10 years, whatever comes last, on the factory fill.

Please, from what you write, anyone can see your are no professional in super high performance engines.
Your small block Chevy, tuned to an extend as your Ducati made with "crappy" components, would win NASCAR races.
You did not realize that, did you?
So do you really thing you could convert a professional, full race engine from carbs to a fuel only, with a 150$ injection system? Tune it on a weekend, with, as you write, "maybe" the use of a wide band in the exhaust?

Do yourself a favor: Forget anything you wrote and take a hand full of $ to get your Ducati serviced by a qualified Ducati technician, not Terry "the fixer" from your lokal filling station with the cheapest fuel state wide. The Mikuni carbs are not complicated, you only have to be qualified to understand them. They are some of the most reliable high performance carburetors in the world. New to you?
Should be better to sell the Ducati to someone who cares for iconic bikes and buy a rice burner or HD.

Maybe you did not like this post, but there is no better advice for you. Not on this planet.

PS Did you know this engine has a cam belt, which has to be changed after 2 years? If it looses a tooth or breaks because of age, your engine is done. A complete service kit with all parts is about 200$, maybe ask what a new heads an pistons will cost you. Tension has to be checked with a special tool, not two fingers.
#52685
theonewithin wrote:
Mon Aug 23, 2021 1:59 pm
Right off the bat though your idea using VR conditioner for the existing VR sensors won't work. You can't share the VR signal.

You would be better off taking a signal from ignition system.
Ah, good to know. I do also have an optocoupler assembly that can get me a square wave from the ground trigger of the coil. The only issue there is that signal will vary between, I believe, 3 and 15 degrees BTDC. I guess this would be the "distributor mode" option I've heard of?
Chris Wolfson wrote:Hi,
a Ducati is a very refined machine.
No, they absolutely are not. They're middling-performance italian tractor engines from the 80s brought kicking and screaming into the 90s and beyond. Anyone who owns a desmodue from the 90s will heartily agree with me that the stock Mikuni CV carbs are paperweights at best, and many will opt to spend $1200 to replace them with Keihin FCRs that will be significantly more reliable and make more power at the cost of your wallet and ability to cold start.

I've had this bike for two years now, always serviced myself with synthetic fluids, run with quality fuel, belts replaced and adjusted (no special tool is required unless you consider a hex key to check the tension "special"), kept an eye out for chaff on the oil screen, replaced the reg/rectifier with a solid-state MOSFET unit, I could go on.

So, please, take your obnoxious attitude elsewhere. You are either deluded or an outsider who has never owned an old Ducati, which are slow expensive garbage that handles mediocre at best but give you a riding experience like absolutely nothing else instantly captivating you in an endless self destructive loop of Stockholm syndrome.
By yingste
#52723
Correct, injectors are ground triggered. All of the injector and ignition outputs are ground triggered along with most everything else. The diagrams in the wiki show that fairly well IMO. I would recommend, if you could, to skip the fuel only setup and put in a standard trigger wheel with a single crank sensor for better results. By taking out the original ignition system and going with a higher resolution wheel you gain a lot more features and tunability which being a sport bike you may want.

If you still want to go ahead with fuel only since you mentioned wanting to keep things mostly stock then yes you would likely be looking at the basic distributor pattern. The wiki has a fairly good writeup on exactly that would entail. I don't
believe you would get sequential fueling since speeduino doesn't have precise info on where the crank is throughout its travel. You also would not get fuel trims either. The more seasoned members should be able to correct if I am wrong.

Looking forward to more Ducati content on the channel
User avatar
By PSIG
#52743
100percentjake wrote:
Mon Aug 23, 2021 5:07 am
Can I simply hook up the Speeduino to the VR sensors in "parallel" with the CDI boxes?
Only if your VR conditioner is high-impedance. There are several types, but the MAX9926 types are high-imp, such as the Speeduino Store conditioner, or the MiniMAX-A2. Opto-isolator types are usually high-imp. Using any conditioner type that consumes signal power (low-imp) can alter the original signal and possibly mess with the function of your ignition, as previously stated.
100percentjake wrote:
Mon Aug 23, 2021 5:07 am
Injectors are ground-triggered, right? 12v-injector-speeduino?
As stated, the injector channels ground. All outputs ground, except ignition (selectable 5V or 12V push-pull / high-low) and stepper IAC (12V push-pull).
100percentjake wrote:
Mon Aug 23, 2021 5:07 am
Is my injector trigger strategy viable?
Sequential only occurs if there is a separate cycle signal (e.g., "cam"), or cam-speed missing-tooth signal. Any method that provides fuel to each cylinder on each cycle is viable. Depending on engine design and dynamics, and the goals of the project, some methods may be more productive or efficient than others.

Likewise, you can cut corners and it can still run quite well, but if you cut enough, it won't. Every decision is a compromise. Plan your compromises carefully in order to reach your goals. For example, the stock ignition works. It could work better and you would see better performance and efficiency. But, it works. If that's good enough for your goals, then you're good. However, as best timing changes with new altered fueling, best performance will not occur (except randomly), especially at low to medium loads. If that's OK (and it's your decision, not anyone else's), then do your thing. 8-)
By 100percentjake
#52772
Thank you very much for your replies!
yingste wrote:Correct, injectors are ground triggered. All of the injector and ignition outputs are ground triggered along with most everything else. The diagrams in the wiki show that fairly well IMO.
I suppose my confusion here mostly stems from my STEM (hah, get it?) classes in college using arduinos and various shields to make simple robots. Sensor positive goes to a positive on the shield, negative to negative, then it works. Something about automotive context completely makes my brain break and I second-guess absolutely everything.
If you still want to go ahead with fuel only since you mentioned wanting to keep things mostly stock then yes you would likely be looking at the basic distributor pattern. The wiki has a fairly good writeup on exactly that would entail. I don't
believe you would get sequential fueling since speeduino doesn't have precise info on where the crank is throughout its travel. You also would not get fuel trims either. The more seasoned members should be able to correct if I am wrong.
Awesome, that all makes sense.
Looking forward to more Ducati content on the channel
I can't go anywhere anymore :lol:
PSIG wrote:
100percentjake wrote:
Mon Aug 23, 2021 5:07 am
Can I simply hook up the Speeduino to the VR sensors in "parallel" with the CDI boxes?
Only if your VR conditioner is high-impedance. There are several types, but the MAX9926 types are high-imp, such as the Speeduino Store conditioner, or the MiniMAX-A2. Opto-isolator types are usually high-imp. Using any conditioner type that consumes signal power (low-imp) can alter the original signal and possibly mess with the function of your ignition, as previously stated.
My VR conditioner is the WTMTronix dual VR conditioner seen here: https://wtmtronics.com/product/dsc-dual ... tioner-vr/

No mention that I can find on if it's high or low impedance, but since they sell another MAX9926-based conditioner I'm going to assume this one is low.

So... I also have a CoilX RPM signal conditioner https://wiki.autosportlabs.com/CoilX

I guess the move then is to hook that inline with the coil ground and wire it into pins 23, 25, 28 on the Speeduino. It appears to output a 5v square wave so no additional conditioner will be required.
100percentjake wrote:
Mon Aug 23, 2021 5:07 am
Is my injector trigger strategy viable?
Sequential only occurs if there is a separate cycle signal (e.g., "cam"), or cam-speed missing-tooth signal. Any method that provides fuel to each cylinder on each cycle is viable. Depending on engine design and dynamics, and the goals of the project, some methods may be more productive or efficient than others.

Likewise, you can cut corners and it can still run quite well, but if you cut enough, it won't. Every decision is a compromise. Plan your compromises carefully in order to reach your goals. For example, the stock ignition works. It could work better and you would see better performance and efficiency. But, it works. If that's good enough for your goals, then you're good. However, as best timing changes with new altered fueling, best performance will not occur (except randomly), especially at low to medium loads. If that's OK (and it's your decision, not anyone else's), then do your thing. 8-)
My goal here is "make it work, make it cheap". The only alternative to the restrictive finnicky factory carbs is a $1200 (sometimes you'll be lucky to find a pair for $800) set of FCRs and then you no longer have a choke and they cold-start like crap... I'm very curious what the minimum viable setup is to have a rideable motorcycle, something easily adaptable to a wide range of bikes.

Additional question:
The "injector wiring" page says there are four circuits, and shows Inj 1/2/3/4. Fair enough. Then the pinout has "Pin 1/2" and "Pin 2/2" for each of these. Is this to assist with batch firing? Would I wire my two batch-fired injectors to "Injector 1 - Pin 1/2" and "Injector 2 - Pin 1/2", or would I do "Injector 1 - Pin 1/2" and "Injector 1 - Pin 2/2" because they are logically "one injector" due to being batched?
By LPG2CV
#52773
yes, but not just for batch. One could have as heavy a wire, or as thick traces on the board as you like, but the current still has to travel through the pin. These can become the weak spot in the circuit, so 2 pins carries twice as much current.
#57613
I've finally started actually making progress on this project by making most of the pigtails necessary. TPS, injectors, and my opto-coupler-based ignition conditioner have been given, uh, healthy amounts of wire to allow for slapping components wherever on the frame I need them.

Next step is to buy a fuse box, get the Speeduino booted up, wire up the optocoupler and see if my RPM shows up in TunerStudio. If so, I'll wire up the injectors and TPS and make sure those work, then disassemble the bike and start installing parts.

I believe my methodology here, Alpha-N with batch injector triggering, is exactly how the factory-fuel-injected 900SS from '99-'07 worked, except those also has timing control in the same box (which was absolute trash, consisting of the roughest map imaginable, and hardly an improvement over the fixed-advance timing of the earlier carb bikes). I'm reasonably confident I'll eventually be able to get this to a satisfactory state of running.

Right now most of the question marks pertain to fuel. I have a fuel pump from the later bikes, but I'm absolutely at a loss as to how they regulate fuel pressure. Factory diagrams occasionally make reference to a fuel pressure regulator, but there is nothing on my fuel rail nor any provisions for it. I bought a fairly universal 47psi "fuel pressure regulator" that appears to be no more than an orifice tube. Guess we'll see how that goes.
Attachments
IMG_4353.jpeg
IMG_4353.jpeg (4.23 MiB) Viewed 549 times
By LAV1000
#57616
Running an 944 watercooled Ducati engine (ST2) in an Cagiva Elefant.
Wich uses the ame throttle body
FPR isn't vacuum referenced.
And it is bolted in between the V of the cilinders.
Attachments
FPR.jpg
FPR.jpg (246.64 KiB) Viewed 517 times
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