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Any questions you have before you begin buying, building and installing.
By Izzy46
#59009
I have a 2005 Mastercraft X-Star with a Indmar MCX350 (Basically a fuel injected, distributor ignition, drive by wire 350 Chev). The boat has had a tough life living in the salty waters of the Persian Gulf and has numerous engine harness and ECU faults. The engine, gearbox and hull are in good condition so I would like to breathe life back into the boat with a Speeduino.

Over the last few weeks I’ve been researching the forum, reading the manual and following build posts from other members. In particular Dstage’s posts about drive by wire and Apollard’s Speeduino boat build posts have been really useful to me. I’m a relative newbie to open source ECUs but I think I’m ready to buy the required components and get started.

Before I take the plunge I’m hoping that someone can have a look at my assumptions to see if I’ve missed anything obvious or not so obvious. :)

Speeduino
I plan to build or buy a Speedy without the built in MAP sensor. Is it possible to get a Speedy built through a service such as JLPCB and then make a financial contribution to the community or is it better to buy directly with one of the three recommended stores?

DStage DBW board
I’m assuming that this is the current best solution to the DBW issue?
Is the only option to purchase this board from JLPCB?

GM 8 Pin Conditioner
Is it best to go down this route or to hook up to the existing crank angle sensor?

TPS
It seems that my TPS is a 6 pin. Will this work for the project or will I need to find an alternative. The link to the TPS is here.

MAP (Manifold Pressure)
I plan to use the stock MAP on the boat.

Temperature Sensors (CLT and IAT)
I guess the stock sensor will be fine here too?

Exhaust Gas Oxygen Sensors (O2 and WBO2)
I plan to purchase this wideband O2 sensor and mount it at the exhaust manifold elbow.

Injectors
Need to check the impedance, once again stock.

Coils
The coil I have is a standard GM coil

Aux Outputs
Is it better to control the fuel pump with a relay or a HC MOSFET?

Auxilary IO
I would like to add a fuel pressure input in the future.
I would also like to add a bluetooth module in the future.

I’ve mapped out the basic build diagram at the link here.
I’ve also created a spreadsheet with approximate costs for the project.

It’s been great to read the Speeduino documentation and to learn from builds of other community members. I plan to document my own process so that others can learn from my mistakes. Hopefully my assumptions are in order so far and there are no deal breakers in this project. Thanks again to anyone who comments on my plans so far, I’m excited to get going!!
#59013
Welcome! This should be a good straight-forward project, keeping in-mind the boat has issues in the current system (some of which you will reuse).

Random in the few minutes I have right now:
  • Use a qualified vendor. You know what you're getting, and should get support for whatever you buy. This is important, as the forum members are NOT the vendor support team. :lol: You also find other versions of stuff you may consider.
  • I would think a weatherproofed ECM version would be appropriate, DIY waterproofing or designed for that.
  • I'm not up-to-date on latest or appropriate DBW. Ask in those threads with specific info about your TB and throttle sensors.
  • I don't understand your GM 8-pin question. Better than what crank sensor?
  • The TPS is fine, and dual-output for the DBW. The ECM will tap (share) only one of the outputs with DBW (only 1 input to ECM).
  • Factory MAP is fine. Get the Speeduino MAP installed and use it as real-time barometric sensor or alternative source.
  • Stock CLT and IAT are OK, but test them.
  • WBO2 requires a separate controller, which usually specifies or supplies the sensor. The controller sends the processed signal to the ECM.
  • My reference says your injectors are 260cc/min at 3 bar, and high-impedance.
  • Stock coil is fine. If you have an 8-pin firing it you can follow this instruction in the Wiki. Other options depend on other things.
  • Control the FP with a relay. The relay is controlled by a Speeduino power output, existing, repurposed, or built in the proto area.
  • Aux input configurations and Bluetooth are both in the Wiki. TS is already set-up for fuel and oil pressures under Accessories.
  • A relay will power the coil and the ignition module, often same relay as FP. Low-volt signals from ECM directly to module.
I have not reviewed your diagrams yet, until I have time.
Will you directly fire the coil with the ECM, or use an aux box (MSD?) to do it? Why? List your goals or requirements if they are different than "run a boat engine in normal conditions".
I have mentioned the Wiki several times. Use it. Learn to search it. Ask questions that the Wiki or previous posts do not answer, and be specific what you are asking for quick and specific answers. Have fun!
#59015
Thanks PSIG you are a legend!! :) I will spend some more time on the wiki and try to be more specific with my questions.
Use a qualified vendor. You know what you're getting, and should get support for whatever you buy. This is important, as the forum members are NOT the vendor support team. You also find other versions of stuff you may consider.
Roger that! I will use one of the three recommended on the website.
I don't understand your GM 8-pin question. Better than what crank sensor?
From my understanding the GM 8-pin distributor module is used to sense the crank angle as well as used to fire the distributor. From Appolard’s post in the manual it seems that an extra circuit needs to be added to the board to clean up the signal coming from the distributor. I was wondering if it is easier to take the signal directly from the crank?
I would think a weatherproofed ECM version would be appropriate, DIY waterproofing or designed for that.
Will do, I will be using this case. I’ve also noticed that marine ECUs are bathed in some kind of semi-viscous gel, I wonder if I could further waterproof the ECU with that…
WBO2 requires a separate controller, which usually specifies or supplies the sensor. The controller sends the processed signal to the ECM.
OK, that’s good to know, I will look into this further, hopefully one of the vendors has a sensor and controller I can purchase.
Will you directly fire the coil with the ECM, or use an aux box (MSD?) to do it? Why? List your goals or requirements if they are different than "run a boat engine in normal conditions".
I was not aware of these MSD boxes. For now I will fire the coil directly from the ECM.

My goals for this build:
  • Make a reliable setup with complete wiring
  • loop in the existing CAN gauge setup. I’m not sure if this is even possible as the gauges receive their signal from a marine media data condenser (MMDC) under the dash. I’m under the impression that the signal is proprietary and difficult to emulate…?
  • If this is not possible, build a touch screen gauge setup and control panel.
  • If all goes well, build a perfect pass system that acts like a cruise control for the boat.
The boat is used for wakeboarding with the family so spends most of its time launching from 600 to 3500 rpm. She is basically an amphibious tractor pulling people along at low speeds pushing lots of water, making big waves. :)
#59021
Izzy46 wrote:
Fri Oct 21, 2022 5:22 am
From my understanding the GM 8-pin distributor module is used to sense the crank angle as well as used to fire the distributor. From Appolard’s post in the manual it seems that an extra circuit needs to be added to the board to clean up the signal coming from the distributor. I was wondering if it is easier to take the signal directly from the crank?
I see, and to be clear it's the distributor's cam-speed signal for crank position — not a separate wheel physically on the crank or something. No problem. Technically, yes, you can do either. However, using the module's output to Speeduino is a bit simpler for similar results. Note the Bypass function is optional (but recommended), and the signal circuit can be more easily replaced by a plug-in signal conditioner module from your vendor to clean-up the signal. Any of the commonly available signal conditioner modules should do for this.
Izzy46 wrote:
Fri Oct 21, 2022 5:22 am
… I’ve also noticed that marine ECUs are bathed in some kind of semi-viscous gel, I wonder if I could further waterproof the ECU with that…
Sure, and there are several common ways to weatherproof, from coating with clear acrylic paint (is still repairable and solderable through the coating), to potting compounds and gels. Use what's easy and convenient for your anticipated and future needs.
Izzy46 wrote:
Fri Oct 21, 2022 5:22 am
For now I will fire the coil directly from the ECM.
Easy. Using the 8-pin and stock coil, you're done with that portion.
Izzy46 wrote:
Fri Oct 21, 2022 5:22 am
My goals for this build:
  • Make a reliable setup with complete wiring
Cool. I haven't seen your diagrams yet, but you're already on-track. Inspect and test every used component. Use marine or aircraft standards for connections. Use silicone dielectric grease on every connection, weatherproof or not. Reliability is mostly in preparation and final installation.
Izzy46 wrote:
Fri Oct 21, 2022 5:22 am
  • loop in the existing CAN gauge setup. I’m not sure if this is even possible as the gauges receive their signal from a marine media data condenser (MMDC) under the dash. I’m under the impression that the signal is proprietary and difficult to emulate…?
  • If this is not possible, build a touch screen gauge setup and control panel.
  • If all goes well, build a perfect pass system that acts like a cruise control for the boat.
While these are later steps, I suggest a quick look at what CAN options you have from the Wiki and your vendor. Build them in now, or wait and run it with a tablet and TunerStudio initially for tuning, and go with more options as it's ready for them. By then, you'll have a much better idea of what you want and can do, and how. Go do your thing! 8-)
#59025
OK, that's great, the ducks seem like they're almost lined up!

There is one more wrinkle that I discovered yesterday after talking to my marine mechanic friend. It seems that the Indmar exhaust manifold has a water jacket the keeps the manifold cool. It appears that drilling a hole for an O2 sensor would be very difficult without compromising the cooling system. I was however able to find a manifold spacer online that might do the job.

https://tinyurl.com/bdfh2y65

Is it viable to go without the o2 sensor or is it better to go ahead with the manifold spacer?

Thanks again!
#59026
Izzy46 wrote:
Sat Oct 22, 2022 5:54 am
Is it viable to go without the o2 sensor or is it better to go ahead with the manifold spacer?
Deleting the WBO2 function would greatly limit the system's capabilities and function, while tuning (quickly and accurately) would be much more difficult.
#59037
So I'm just about ready to pull the trigger and make the required purchases.

I intend to purchase everything on the 'ECU' sheet on this spreadsheet.
https://docs.google.com/spreadsheets/d/ ... sp=sharing

I think everything is in order, I just can't seem to work out whether I need the dual signal VR conditioner or the mini max A2 VR conditioner. I read the documentation in the manual but can't determine which condition is more suited to my needs.

Dual Signal
https://wtmtronics.com/product/dsc-dual ... tioner-vr/

Mini Max
https://wtmtronics.com/product/mini-max ... tioner-vr/

Any help would be greatly appreciated :)
#59039
It is very close to the exhaust port, if your WB interface doesn't report sensor temperature then I would set up a probe, you may well find that its over temperature under load and the readings can't be relied upon.

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