megasqirt/microsquirt on a mercury 2.5 race outboard

[actmobmar]

i am considering installing a microsquirt on a mercury 2.5 liter race outboard, v6 engine, horsepower around 300 naturally aspirated. i don't need to control spark, just want to control fuel injection, engine is currently injected using bosch injectors, the efi computer is getting its signal from a crank trigger(has 3 independent legs that are mounted to a disc that moves mechanically to advance/ retard timing. each of these pickups generates .2-2 volts dc when triggered, can i use one of these to run the efi? also, what sensors would i use? has this been done??? thanks for all your help!!!!

[Matt Cramer]

Is that a VR sensor setup? You might be able to use it if you have a good zero crossing.

[actmobmar]

sorry, but what is a vr setup? most of the time when i ck the trigger output on these engines it is 2 volts, the way it works is there are 2 cdi boxes, each trigger has 2 wires, total of 3 triggers, 1 leg goes to the outer box, one to the inner, three times, thats how it figures whn to fire each cylinder, firing order is 1 2 3 4 5 6!

[whittlebeast]

There are two basic types of cam/crank sensors out there. VR sensors are essentially just a magnet with two wire coming out. Teeth normally sail past this thing and it generates some sort of sin wave looking signal to the Squirt. The sin wave gets bigger (more voltage) as the speed of the teeth increases. Commonly found as wheel speed sensors.

The second version is a Hall effect device that has 3 wires. Ground, power (normal 12 volts) and an output signal that is either 0 volts output or 5 -12 volts output (depends on the device) based on if a piece of steel is close to the device. These are very common on camshaft sensors.

Plan on running a mass air flow device on a two stroke. Simple speed density and alpha-n is a fight on a two stroke. You may get by on alpha-n if you can get the map sensor in the transfer port and get the MAP signal at exactly the correct time in the crank rotation.

Hope this helps

AW

[actmobmar]

i appreciate it! these engines are factory fuel injected, they don't use a coolant temp sensor, just air temp,rpm, inlet air temp and a map sensor(senses off a common plenum), they don't even use a tps! thats why i was wondering about the map sensor on it. is it worth a try to see if the computer will be triggered by the factory ignition pickup? when the computer sees this pulse is that when it batch fires both banks?

[whittlebeast]

I found that the MAP that I found under the throttle body was almost useless. If that MAP sensor is in the crank case it may be usable. It will be a challenge to get AE to work without a TPS and without a usable MAP signal to trigger off of. I am leaning had in the direction of adding a TPS somewhere as well as a watertemp sensor (if possible) to the water jacket. If not, starting in the cold may wind up as the big issue. Is there any way you can get a MAF mounted into the air stream? I would bet the new Ford stuff is fairly easy to adapt but I have not tried it yet.

Hope this helps

AW