924Board.org

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

OMG Min, I`m not hopping on this EDIS roundabout again and going around in circles with you even if you still enjoy riding it. Clearly, you are heavily emotionally invested in this issue and fail to see things from a logical perspective. FFS, Ford dropped EDIS nearly 20 years ago and moved forward.

As most engineering students know, the more unnecessary hardware added to any system the greater the odds of failure. Basic design principle. Especially in an automotive environment of heat, moisture, corrosion, vibration and with additional wiring and connectors involved.

When MS can directly decode the trigger wheel input signal and then drive whatever coil(s) desired, (including EDIS coilpacks if desired) there are NO advantages of incorporating additional hardware that processes the signal through two stages to arrive at hopefully the same output. I realize the electronics is above your level of understanding Min, but recall posting some links previously that explain the basic operation. Perhaps have a re-read before replying?

Remember?

http://www.924board.org/viewtopic.php?p=309590&highlight=edis#309590

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

I installed 60-2 wheel on the crank on my 931 "Gulf" and welded a 10mm wide tooth on the cam pulley for cam sync which is sensed by Honeywell 1GT101 Hall sensor.
That is because this way I get best timing precision (60-2 on the crank) and fully controllable injection angle. Yes, I use this on my 931 and it has noticeable benefits on engine smoothness and driveability, especially with the biggish 630cc injectors that I use.

If one has to install a trigger wheel anyway, I wouldn't bother putting it on cam because it will result in timing drift and resolution would be half compared to crankshaft mounted trigger wheel (same tooth count).
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Min · Posted: Fri Oct 14, 2011 11:33 pm Post subject:

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

When choosing the ignition system for my EFI conversion. I decided that I wanted to go with a distributorless solution. Because of the potential for better ignition control (something the 924 desperately needs to maximize the amount of power under the curve) and because I really like the cleanliness of a distributorless solution.

I chose EDIS simply because it was a simple solution to install. Fairly self-contained, reliable, well documented and was a known quantity. The fact that I could simply connect the stock tach to the output of the EDIS module was a win to me. Also the fact that I can put the system in limp-in which fixes the timing at 10 degrees means that I have one less issue to fight during first start/basic idle tuning.

I know that the next step is to remove the EDIS module and drive the coil pack(s) directly from MegaSquirt, which does open the door to improvement on ignition control by improving finite control (among other things). However, to do that requires that I move to MS2 (at least) and that is a much larger jump from where I am now as I'd have to determine how to drive the tach from MS, how to translate my timing table over and start to make improvements, etc. I will get there as my goal is to see how far I can take this motor, but I need to make small steps at a time or it will never be driving.

So that is my reasoning, the choice to use EDIS or another ignition system is a personal one. Do your research and determine where your comfort level and ultimate goal is and go that route.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

rx924 · Joined: 11 Oct 2011 Posts: 11 Location: NY

I think i'm going to follow fiat's idea here. Use the EDIS for simplicity and making me run into less problems on my first startup.

Once i get the car running with the EDIS i can simply play with a ton of different ignition ideas since i've got everything else calibrated.

And wouldn't the best Crank or Cam position sensor be one that could be placed where the distributor mounts behind the valve cover? Something like what mazda uses on the 13b rotary's? Just wondering.

I'm glad people are answering my first post here!!!!!!!!

Min · Posted: Sun Oct 16, 2011 2:34 am Post subject:

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

It depends on the ECU which is simpler, EDIS or using IGBT's in the ECU.

With MS it may be easier to use EDIS, but most other ECUs already have IGBT's inside the ECU and how could be installing EDIS with its additonal hardware, proprietary ignition leads and precisely orientating the trigger wheel on the crankshaft easier than just using a generic Bosch coil-pack (cost: $40) and connecting three wire to it (+12V supply and two wires to ECU)?

The orientation of the missing tootl does not matter too much also as the trigger event (missing tooth passes the sensor) just has to happen the number of degrees that your max advance will be and not happen in the spark instant. You just fine-tune the missing tooth location with the strobe light and get absolutely the best precision. You can never get the angle between trigger event and TDC precise by measuring it with degree wheel because VR sensors sense the missing tooth differently.

Have you checked the spark angle with strobe light on the EDIS system to ensure that it is spot on? Should be 10 degrees BTDC without ECU input signal on the EDIS module, easy to check.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Min · Posted: Mon Oct 17, 2011 4:46 am Post subject:

rx924 · Joined: 11 Oct 2011 Posts: 11 Location: NY

Alright so my MS2 and mega stim have come in =)

I've put together the stimulator so far and i'm working on MS slowly when i have free time. I'll post some pictures soon i may make a new post just to show the whole project

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Min · Posted: Thu Oct 27, 2011 11:17 pm Post subject:

rx924 · Joined: 11 Oct 2011 Posts: 11 Location: NY

This is my throttle position sensor. It uses a standard potentiometer with a servo cross attached to it. From the servo cross a bar goes to the axel that rotates from the throttle body. Almost all the parts i used from a hobby RC car box of parts.

rx924 · Joined: 11 Oct 2011 Posts: 11 Location: NY

This is a 3D model of what my entire crank pulley will look like once my lathe/mill comes in.

This is what i'm using to hold the trigger wheel to the crank pulley. The piece in red is what i am cutting out on the mill. I'm going to weld it to the pulley and then weld the nuts on it to make easier to bolt down.

flosho · Posted: Thu Dec 22, 2011 9:49 am Post subject:

One thing you may want to consider is how the trigger wheel is bolted to the crank pulley.

You have the elongated holes running from the center towards the edge, but this only gives you a limited number of adjustments. It also could lead to the trigger wheel not being perfectly centered on the crank pulley which could cause additional issues.

If the trigger wheel has slots in it that go around the wheel, you will have better ability to index the trigger wheel to the proper spot.

I believe that is how my trigger wheel is (from the original group buy) and many others with adjustable wheels use this method...

If your trigger wheel is pre-made I would look for a solid one and mill your own slots.
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