924Board.org

[WEASEL149]

Ok. I've been contemplating going the full EFI route for a long time but for now I can't quite bring myself to pull apart the CIS which has always run perfectly on my car.

What I would like to do is upgrade from the distributor timing to fully programmable ignition.

Now when I bought the car 10 years ago, even though it's a S1, it already had the later flywheel/trigger wheel from the S2 fitted by the previous owner along with the S2 throttle body.

From what I've read from the forum, the original S2 crank sensor is NLA from Porsche but the crank sensor from a BMW 2.8 apparently fits with minor work?

Could I use something like VEMS purely to run the ignition and not fuelling, and so giving me a future upgrade path to full EFI?
This would be using the original 60-2 trigger wheel with the BMW crank sensor and a new TPS sourced from another car, along with the other sensors I would need (MAP etc.).

I do also like the look of the DTA stuff and I've seen that they offer an ignition-only ECU.

Ideally I would like to avoid mounting another 36-1 trigger wheel and going the Ford EDIS route...
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1979 UK 932

[fiat22turbo]

Look into MegaJolt:

http://www.autosportlabs.com/

Might be right up your alley.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[WEASEL149]

[ideola]

Well, for starters, the S2 "trigger wheel" is not a 60-2 setup...so triggering off of the sintered insert on the flywheel will require a system that can be set up for a completely custom arrangement.
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erstwhile owner of just about every 924 variant ever made

[Min]

[ideola]

The DITC-equipped cars have a sintered insert on ring gear. There is no missing tooth. So the crank trigger picks up on the sintered insert when it comes flying around, as opposed to detecting a missing tooth. Sort of the inverse of how missing tooth setups work. I don't recall offhand how many teeth are on the flywheel though. I'm sure there's a way to get it to work, but honestly, I think you'd be better off to just bite the bullet and figure out how to mount a proper 60-2 or 36-1 wheel up front. Having to dork around with the flywheel inside the bellhousing and the reference sensor mounted to that little tiny window is a royal PITA once the engine is in the car. I'd rather have my sensor and wheel up front for easy access.
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erstwhile owner of just about every 924 variant ever made

[Min]

ya, that sounds pretty bleh alright, not sure if anything out there right now could properly trigger off that.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

[ideola]

Here's a pic of the S2 flywheel:

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erstwhile owner of just about every 924 variant ever made

[WEASEL149]

[Min]

[fiat22turbo]

MegaJolt is just a customized version of MegaSquirt.

If you need more resolution and the ability to grow, then buy a standard MegaSquirt (V2 or V3) and load the MSExtra code on it. There is even a High-Resolution code option for MS1/2. Also you can adjust where you want more resolution by adjusting the scales on the sides of the graphs in the tuning software to focus on areas where you need the extra control.

Using a standard MS, I would simply modify the MegaSquirt to drive whatever ignition system you'd like. You can drive coil packs directly from MegaSquirt and have much more finite control. You could even use COP or individual coils for each plug. Read the ignition hardware manual:

http://msextra.com/doc/ms2extra/MS2-Extra_Ignition.htm

With the sensor that the BMW and apparently Porsche use, I suspect they are Hall Effect sensors, so read the section on using Hall Effect sensors in MS Extra to pick up how they are used.

As for using the full MegaSquirt to just drive ignition, don't connect the injectors and run the injector pulsewidth at .1ms (to protect the drivers on the circuit board) and you'll be fine. You'll also be ready to add fuel injection when you're ready to.

Finally, if you want add knock control, add a Knocksense to it. There's also an option for shift lights, flat shift/launch control, etc.

Obviously, MegaJolt and MegaSquirt aren't the only game in town when it comes to EFI or ignition. They aren't even the "best of the best" solutions. They are however, some of the best bang for the buck options and their open source nature means they will grow and change to meet your needs now and in the future.
_________________
Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

[ideola]

[WEASEL149]

[WEASEL149]

[WEASEL149]