Porsche 944 MS questions.

[dahgzmikael]

Hi all.

I, like I once assumed many others, have decided megasuirt is the way to go for my 1985.5 Porsche 944. No, its not a turbo, no I have not done huge modifications, but my computer in the car is going out, slowly but surely, and in looking for a replacement, I come accross megasquirt. Now, I have no tuning experience, but I am extremely pc savvy, have been programming chopping ripping editing and destroying everything electronic I come accross for the last 15 years, so this seems right up my alley. I am fully confident I can commit to making this work. That said, please dont bash me for taking the hard road. I want to learn.

Now. My 944 uses hall effect (reference sensors, bolted to the top of the bellhousing, counting teeth on the flywheel) sensors to run the ignition. I used to believe the DME read the signals, counted the teeth blah blah blah, and chose when to ground the coil, from the DME. I'm not 100% if this is the case, or if the signal goes from the cpu to a "coil enabler" like the bosh 124 system. So, I guess thats question number uno...

General question here, is, what will run the ignition timing for megasquirt? I have read the VW watercooled install info on DIY tune, but it pertains to distributored systems. Although it does have a section reguarding the bosh 124(5?). So, is that the system my car uses? the 124? I havent been able to confirm this.

Also, would I have to set this up as sequential? I read something suggesting ms has but two injector drivers, thus sequential is "difficult"?

What all do I need sensor wise, and whatnot, to get this going?
I already have a map sensor output on my intake manifold.
Should I use the "on off" TPS of the 944, or the "variable voltage" tps off a 951?
Get a GM IAT sensor and delete the AFM?
Normal, stock coolant sensor?

I guess, can megasquirt control my ignition the way it is, or do I need anything else?
And am I missing anything here?

Appreciate any responses, critical or not. A search for "porsche 944" on this forums yields but 4 results, and porsche 944 ms on google isnt much help either.

- Dahgz

[Matt Cramer]

Hi all.

I, like I once assumed many others, have decided megasuirt is the way to go for my 1985.5 Porsche 944. No, its not a turbo, no I have not done huge modifications, but my computer in the car is going out, slowly but surely, and in looking for a replacement, I come accross megasquirt. Now, I have no tuning experience, but I am extremely pc savvy, have been programming chopping ripping editing and destroying everything electronic I come accross for the last 15 years, so this seems right up my alley. I am fully confident I can commit to making this work. That said, please dont bash me for taking the hard road. I want to learn.

Now. My 944 uses hall effect (reference sensors, bolted to the top of the bellhousing, counting teeth on the flywheel) sensors to run the ignition. I used to believe the DME read the signals, counted the teeth blah blah blah, and chose when to ground the coil, from the DME. I'm not 100% if this is the case, or if the signal goes from the cpu to a "coil enabler" like the bosh 124 system. So, I guess thats question number uno...

General question here, is, what will run the ignition timing for megasquirt? I have read the VW watercooled install info on DIY tune, but it pertains to distributored systems. Although it does have a section reguarding the bosh 124(5?). So, is that the system my car uses? the 124? I havent been able to confirm this.

The 944 S we tuned used a Bosch 124 module; I'm not sure about the earlier ones. Using the stock flywheel triggering isn't easily supported; you're best off converting to a 36-1 or 60-2 crank trigger.

Also, would I have to set this up as sequential? I read something suggesting ms has but two injector drivers, thus sequential is "difficult"?

There is no absolute requirement to run sequential here. Sequential injection would call for either an MS3 or an advanced application of the MS2/Extra code, both of which have a separate support forum at MSExtra.com.

Should I use the "on off" TPS of the 944, or the "variable voltage" tps off a 951?

Variable is better.

Get a GM IAT sensor and delete the AFM?

That's usually good for a few horsepower.

Normal, stock coolant sensor?

That should be fine as long as you calibrate the MS for it.

I guess, can megasquirt control my ignition the way it is, or do I need anything else?

As noted above, the easiest option to run the ignition is an alternate crank trigger.

[dahgzmikael]

Appreciate the information. I presume by alternate crank trigger, you refer to a trigger wheel/pulley, which in my case would run where the distributor cap is, using a hall sensor, going to the ms. I read 3.0v boards can control a Ford edis without need of a vr conditioner or extra board? So, hall sensor - ms directly? Then ms to coil neg, coil to coil pack, to plugs? I just want to be sure I'm reading correctly.

much appreciated. ill keep reading the manual to try to understand what's going on here

[dahgzmikael]

Ok, now I understand a little more. but do I have to run the vr trigger off the crank? Can I set it up on the cam? I have seen this setup on a 924 but I'm not sure if it was ms...

[trakkies]

If you're going wasted spark, you only need a crank trigger. A crank trigger is also more accurate than a cam one - no drive chain etc to wear. Using a complete Ford EDIS set is the easy way - but you'd need to check it allows high enough revs for your engine. I'm not sure what the rev limit is with EDIS, but have been told it is too low for some uses.

[Matt Cramer]

Ok, now I understand a little more. but do I have to run the vr trigger off the crank? Can I set it up on the cam? I have seen this setup on a 924 but I'm not sure if it was ms...

Your trigger wheel can turn at crank or cam speed.