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Fuel only MS without CPS?


elbekko
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I've done a bit of googling, and it does look like it's possible; here for example. If a coil output works, a 4 pulse/rev signal should work fine as well, no?

If I set up a fuel-only board without crank trigger, would it be easy to add crank-trigger and ignition later? Or does it need actual components changing?

I'd like to get MS to replace my LPG ECU, but would like to leave the option open of going full MS later on if I feel like it. Hence fuelling only is good enough for now, the timing curve put out by the Bosch ECU is good enough for the LPG.

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Depends a bit on what ignition system you're currently on, and what system you might want to end up on.

If you're on dizzy you use the basic opto-isolated input.

If you're on coil packs from the factory ECU you'd probably channel either the crank sensor into the VR input circuit, or diode-OR the coils together into the opto-in.

Both those would be build-time options for the MS, you'd have to populate the components & solder jumpers to connect the required input conditioning circuit to the CPU's TACH pin.

If you then wanted to move to EDIS or direct coil drive you'd have to reconfigure the input again. Only exception would be if you were already using the crank sensor into the VR-IN circuit and wanted to go direct coil drive - but yu'd still have to build a coil-drive output circuit.

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Current system: stock Bosch/Thor in my P38. Electronic ignition with EDIS-like coil packs driven by the Bosch ECU. Maybe in the future I'd like to let MS trigger them, either through EDIS or just DCD, I doubt EDIS has much advantage here.

I was thinking of using the cruise control tach signal for the MS, that's 4 pulses/rev and is what the current LPG ECU is hooked into.

Would the VR signal be strong enough to use for both MS and the stock ECU? If so, that's probably the preferred option, as that leaves more room for DCD in the future. MS should be able to handle the 60-2, right?

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Oh, excellent. Time to start drawing up some plans then...

... And find someone who wants to build the damn thing, because my soldering skills are limited to putting down huge globs of barely consistent metal.

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When I did my install I used very similar coil packs but instead of building the ignitor box I used Subaru external ignitors, there are so many good ignitors around it wasnt worth the effort. I was originally after Mitsi EVO ones but the Subaru ones were much easier to get hold of. There are even Bosch 4 channel ignitors available

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