Any questions you have before you begin buying, building and installing.
User avatar
By Brian Shaw
#53072
Toying around with the idea of replacing my jet ski ecu with speeduino. I have a bad ecu in my Seadoo ski and they are pricey. It's a 2 stroke 787 2 cyl. and it has what they call DESS. It has dual carbs and CDI type ignition (driven from the ecu(mpem)). The cdi is in the main ecu with the dess (theft security and safety shutdown). The ignition probably has 3 or 6 pulses(3 phase 18 pole alternator) and the crank signal is driven at the same location. I may have to add a proper crank signal.
I have a few questions. Will this function as a ignition only system? There was some debate on the arduino site if the arduino was fast enough to do high RPM's. This engine needs 7000 RPM's. It needs a defined timing curve of 16 to 25 degrees at about 20 points. Preferably I have a shutdown of some some sort. Fuel and oil have their own systems and will not be used unless it should become another project.
Board recommendation?
What tuning software is contradicted for this project?
Is this doable?

Brian
User avatar
By PSIG
#53074
Whoa, lots of Q's. Hello. I'm not familiar with your specific system, but CDI can be controlled. 7k is OK. Timing is 2D 16 points or 3D (TPS or MAP x RPM) of 256 points (16 x 16) First necessary info is your crank position signal info and the CDI trigger voltage and polarity. Your safety shutdown parameters are doable with required info. Pick any board with 2-channel ignition or more, such as the NO2C. Once system is proven with any necessary mods and depending on future goals, then optionally change to smaller or more specific such as a Blitzbox, Core4, UA4C, etc. Most important — have fun! 8-)
User avatar
By Brian Shaw
#53174
I plan to use the ua4c. I've become more educated now but it has created a few more questions.

I have no TPS or MAP. I assume I would get the 250kpa to go onboard and the TPS will be GMxxxx.

The old cdi was in the mpem so I plan to use the gm smart coils.

Temp transducers are easy , even if I have to make them.

The questions are about the triggers. The old mpem used 2 triggers from the magneto. It has a sensor that "sees" two metal plates welded to the magneto rotating assembly and a sensor. This is what I am going to try. I have some optical sensors on the way. With the parameters I have I can get a 12-1 or 12-0 trigger. This is a 2 stroke so this will fire 2 cylinders every rpm (360) not (720). I would like to use dual wheel trigger and use the OEM sensor also. Is this possible and does it help?

O2 sensors wont work on 2 stroke. I may do EGT for my Arduino display. I'm not sure if it helps speeduino.

What am I missing?

Any input is appreciated.

Brian
By theonewithin
#53186
Just use the 12-1.

No need for anything else.

Widebands work fine on 2 strokes.

You could always remove it once tuned though.

You could run just MAP sensor and no TPS. It's not NEEDED to work.

Just tie the input with a resistor to GND so it doesn't interfere.

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