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No RPM indication with MS3 V3.0


seth1001

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Alright I reflashed the board with the firmware and got that light to go out. I'm not sure why it came on in the first place but it's out now so who cares. I'm still not getting any rpm indication. Everything looks good as far as the assembly goes...What could I possibly be missing at this point?

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At this point I would have to put a scope on it to see that the stim is really producing an rpm signal and then if the signal makes it up through the opto isolator circuit. I don't know what else to tell you at this point. Can you try your stim board on a different megasquirt to make sure it sends and rpm signal? Anyone local to you that can help with that?

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I don't know of anyone around here that has a megasquirt...is there some way to check the pins with a multimeter and see if the stim is putting out rpm?...also I guess I could just hook the thing up to my car with the wiring harness and just hook it up to the coil negative....try starting the engine and see if a tach signal shows up on the screen...

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Man alive, what a pain in the ass. Anyway...I figured out what the problem was. Apparently my stim doesn't have enough voltage to push the tach signal through the D2 diode...so I had to jumper the diode. Now it seems to work like a champ. I'll just have to unjumper it before I put it in the car and hopefully it will work. I found the answer in the MS2 troubleshooting section...which is something I've been trying to avoid so I don't confuse the 2 stuff with the 3 stuff...considering I've never used either before. Now I just have to figure out how to wire the damn thing in. I'm confused as to how I'm supposed to wire the thing into the ignition system...do I just grab an ignition wire where I can and splice it in there?...maybe with a fuse?...doesn't seem right to me but anyway...I've seen all the cartoon wiring diagrams but an actual photo of the power and injector wiring on a car would be great...anybody have one?

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Without knowing your car, engine, current ingition setup and any other details it is hard for us to help. If you have a distributor and single coil, then you run a wire from the coil negative terminal to the megasquirt input.

 

EDIT: I meant it is hard to supply a specific photo of the wiring when we don't know if you have a 240z and stock engine or 280zx and stock engine for example.

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If you have it built for coil (-) triggering, you have to short out the Zener diode to get the stim to pass RPM signal. I just soldered part of a component lead across the legs.

 

Hooked up the stim, loaded the firmware, cut the jumper through the diode, plugged it into the car and off it went.

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