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TUTORIAL alternative to the DITC ignition, MSD 6530
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jaspervanweerd  



Joined: 03 Dec 2012
Posts: 22
Location: Netherlands

PostPosted: Wed Feb 13, 2013 8:57 am    Post subject: TUTORIAL alternative to the DITC ignition, MSD 6530 Reply with quote

WHAT?
In this topic I will describe how to replace the DITC ignition and replace it with a new, programmable MSD ignition system.

WHY?

First off, why would you want to replace the DITC system in our beloved S2 turbo’s. Well A it concerns quite old technology and B when broken it costs a fortune to replace and parts a becoming more and more difficult to come by. Often, only second hand parts are available since they are not manufactured anymore. An added benefit of fully programmable ignition is that you can optimize performance for the fuel quality your desire, in my case EURO/RON 95 and make adjustments for better performance or economy.

WHAT DO YOU NEED/COSTS?

This tutorial/guide shows how to replace the DITC ignition only, people that are interested in going full EFI, this might not be your cup of tea.

I chose to use the MSD 6530 6AL-2 programmable ignition unit. This unit is fully programmable and allows you to map vacuum advance as well as boost retard maps. All the required parts and tools are listed below with the price I paid for them (excluding variable costs like shipment and customs):

$ 380,- MSD 6530 (ignition computer)
$ 80,- MSD 3bar MAP sensor (pressure sensor to allow for boost retard)
$ 100,- Locked out distributor with pickup sensor (to provide ignition trigger)
$ 80,- Timing light (to set the initial timing)
$ 15,- Com-to-usb cable (to hook up the computer to the MSD unit, mine lacked a COM port)
Soldering iron and paraphernalia...(to extent a part of the wiring loam)
Simple tools (to undo the dizzy, drill holes etc.)

NOTE: MSD also sells a 6AL-2 which is not programmable, carefully check the cat# 6530







In the pictures you will see all the parts laid out. The costs might seem steep but keep in mind you can sell your old DITC parts !!! I strive to break even with selling my DITC system i.e. the DITC computer, Flywheel sensor and Ignition amplifier.

BACKGROUND INFO?
To calculate the ignition timing the computer must know the position of the pistons during their stroke. Unlike the DITC ignition the MSD uses either Hall-effect or magnetic pickup to determine Top Dead Center, TDC. DITC makes use of a Variable Reluctance, VR, sensor that reads the flywheel. To my knowledge the MSD unit can’t read that signal, hence we need another way for the computer to know TDC. The most logical way, and how I did it, was using a ‘locked out’ distributor with magnetic pickup (which I got form Roger, RC). Basically a regular dizzy with the advance locked (either mechanical or vacuum) resulting in a fixed shaft (advance and such is now controlled electronically, come back to that later). So now we can determine TDC, next on the agenda is the manifold pressure. The DITC has a vacuum/boost line that allows it to calculate the amount of ignition retard based on turbo boost, quite crucial. The MSD unit doesn’t has a vacuum/boost sensor included out of the box. It does however allow you to hook up a so-called MAP sensor, Manifold Air Pressure. These come in three varieties, 1, 2 and 3 bar. Note though it measures absolute pressure values. So 1 bar is till 1 atmosphere ( 1 bar), therefore only suited for vacuum reading. 2 and 3 bar can be used for turbo/supercharged vehicles. I choose 3 bar which gives me the broadest range. Once the computer knows TDC and Manifold Pressure it can calculate the ignition and give a spark. For that I use the stock coil which directly hooks up to the MSD box.
OK, let’s talk ignition maps. These must be entered via a PC and uploaded to the MSD box. To better understand this I will explain what the MSD box actually does. Since it can cannot predict the future, it can only give a spark after it has registered TDC. Therefore we need to set a maximum advance setting as the initial value. The only thing the MSD box can do is retard the timing, pull-out degrees, based on the programming ( that why we need the locked-out dizzy). So, full advance is your starting value and the software allows you to set a RUN and BOOST retard curve. RUN curve retards timing based on engine RPM and BOOST on the PSI values provided by the MAP sensor. Boost in this regard also implies vacuum ( 0 < 1 bar/ATM). Example, say you want 20* at a certain RPM/Boost level and your dizzy is locked at 45* maximum advance. Then you need to retard the timing by 25* to obtain this value. Note though that 25* is the maximum retard the 6530 MSD box can provide.

Knowing this we can start converting existing maps into MSD ones, here I used Flosho’s (MAP 1) and Raceboy’s (MAP 2) as an example, assumed 43* locked dizzy.

http://www.924board.org/viewtopic.php?t=37214&postdays=0&postorder=asc&highlight=programmable+ignition&start=15


Original Flosho MAP



MAP 1: above the derived table and below the actual MSD curves


Original Raceboy MAP



MAP 2: above the derived table and below the actual MSD curves

How to actually program the 6530 MSD unit will be explained later on in this tutorial. 


INSTALLATION?
Step 0: Removal of the DITC
Disconnect the battery first, I prefer to remove it completely from the car !!!
Under the heater remove the DITC computer by unplugging the big black connector, smaller one and the vacuum line and pulling it out. Remove the ignition amplifier on the left inner fender well and the flywheel sensor, held in place by one bolt. Be careful it doesn't fall into the opening of the flywheel housing. To remove the flywheel sensor you will need to cut through the rubber grommet. If you do it nicely you can put the cut grommet back in and still provide a good seal.

Step 1: Mounting the MSD 6530

I chose the place the unit inside the glove box. I provides ample space to house the unit and its conveniently located to access it via a laptop, inspect the connectors and view the LED indicator. I removed the whole glove box by undoing the screws that hold it in place. Then I drilled 4 holes in the bottom to mount the MSD on its rubber feet and two big holes in the back to route the wiring through, one on each corner. The picture gives an idea on how it looks.


without wiring


with wiring

Step 2: Prepping the wiring loom

Very little has to be modified on the wiring loom that is provided with the MSD unit. What I did was extending the MAP sensor wire by ˜ 80 cm. I soldered all the connections and wrap the wires in electrical tape, see picture.


extended wire


Top view of the glove box, all the wiring connected

This wire together with the ‘switched 12v’ and the ‘tach output signal wire’ was fed behind the radio where the old DITC box was located. Switched 12v was connected to the black cable from the big black DITC connector and the tach output wire to the green one. I used the crimp connections provided by MSD to make these connections. The MAP sensor was hooked up to the extended wire and connected to the DITC vacuum line. A little lubrication on the MAP nipple and the hose made it easier. Next I feed the ‘Ground’ and ‘12v wire’, ‘Magnetic pickup wires’ (I cut of the connector so I could feed it through) and ‘coil wires’ through a hole in the bulkhead behind the battery. The black power cable goes directly to the negative battery clamp and the red one to the positive clamp. Connect the wires to the clamps first with the battery out of the car for safety reasons. Wire the Coil with the coil wire (connecting pin 15 and 1). Hooking up the magnetic pickup will be described later together with how the mount the replacement dizzy. After you have fed the wires through the hole and behind the battery you mount the glove box (now outfitted with the MSD unit) back in place and fasten it with the retaining screws. I would advise to check and double check the wires, especially the power ones so they are connected on the right pole.

Step 3: The distributor
Next we need to swap out the DITC dizzy for the locked-out one that has a pickup sensor. First I soldered a connector, included in the MSD package, to the dizzy magnetic pickup sensor connector on the dizzy body, see picture.



This connector would hook up to directly to the wiring loam coming out of the bulkhead. Since I cut of the connector of this wire so I could feed it through the bulkhead, I re-soldered it on and protected/insulated it with electrical tape.
To swap the dizzy you can follows Haynes, setting TDC etc etc. However, I have an easier and quicker solution as illustrated by the picture. Remove the cap and mark the center of the rotor on the dizzy body with a heavy duty marker or pencil. Remove the retaining bolt of the dizzy and pull-out the whole unit. Next measure the distance from the TDC mark on the ‘old’ dizzy to the mark you just made. I used a compass to do this more accurately.



Then measure the same distance on the new dizzy and mark the location as well. Again, double check by eye you did it correctly by placing them next to each other. Next you mount the new dizzy in place with the sensor more or less facing the bulkhead and align the rotor with the mark you just made. Note that the rotor will turn when installing it, so anticipate on that. Now you have more or less (depending on how careful you perform this) aligned the whole set-up. Last but not least hook up the sensor wire to the wiring loam.

That concludes the installation from now on everything is done in silico and with the timing light!!!

PROGRAMMING?
Now everything should be in order and the car should fire up. Before we do, we need to upload an ignition file from the computer to the MSD box. For that I first installed the software to control ‘com-to-usb’ wire. My laptop doesn’t have a COM port, if your does this step can be neglected. After that I installed the MSD software.

Before uploading the final ignition map, required to run the car, we first need to set the initial full advance. But first let see if the car fires up. For that I uploaded the standard file where all the values are set to zero, adjusted the amount of cylinder to 4, choose the correct MAP sensor (3bar i.e. 45 PSI) and set RPM limits. Now you can reinstall the battery. After doing this, with the car on ignition 1 (one before starting the car) the PC should find the MSD unit and you can upload the file you just made (always keep a copy on your PC). OK, fire it up, DO NOT apply any throttle !!! In my case I had to jumper the fuel pump relay between pin 30 and 87. I think the relay on my Porsche is nearing his retirement. After doing so. the car started fine, tach worked and all the dials in the software also worked (digital tach gave the same RPM reading). This is where I am at currently…she purrs like a kitten...

Next piece will concern how to set maximum advance and get it all to work…to be continued

Looking forward to your input !!!

DISCLAIMER:I do not take any responsibility to possible damage that could occur due to improper installation or faults in my guide.

PS. Special thanks to Roger (RC) for all the input and willingness to assist, I appreciate it a lot !!! Greeting form the Lowlands (Holland).
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WEASEL149  



Joined: 19 Aug 2005
Posts: 595
Location: UK, Sheffield

PostPosted: Wed Feb 13, 2013 9:37 am    Post subject: Reply with quote

Excellent stuff. I can see quite a few people being interested in this conversion.
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kcoyle  



Joined: 15 Jan 2011
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PostPosted: Wed Feb 13, 2013 10:53 am    Post subject: Reply with quote

Killer work, thank you.
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Rasta Monsta  



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PostPosted: Wed Feb 13, 2013 12:54 pm    Post subject: Reply with quote

Great writeup, thank you for sharing your hard work on this.
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morghen  



Joined: 21 Jan 2005
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PostPosted: Wed Feb 13, 2013 9:41 pm    Post subject: Reply with quote

Rasta Monsta wrote:
Great writeup, thank you for sharing your hard work on this.


+1
MSD is not such a difficult thing to do, even for the average...i was going to say Joe...but i changed my mind

i might install MSD on my 932 !
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!tom  



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PostPosted: Thu Feb 14, 2013 2:08 am    Post subject: Reply with quote

This should be a How-to.
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Joes924Racer  



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PostPosted: Thu Feb 14, 2013 7:42 am    Post subject: Reply with quote

Oo Im Joe.Yea this is destined to b a great How 2.
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jaspervanweerd  



Joined: 03 Dec 2012
Posts: 22
Location: Netherlands

PostPosted: Thu Feb 14, 2013 7:54 am    Post subject: Reply with quote

Hi guys,

Thanks for the kind remarks. I really hope this helps people that are struggling with DITC problems and want to convert to something more reliable and modern. I must admit, it all went easier than expected . Up to this point, I would say this conversion can be done with ease with minimal tools and the whole lot took me just 2 - 3 hours !!! (And I had to figure out how to do it as well ).

I was actually planning, once I finished it all, to make a more polished version a put it up as a How-To.

For now I am still in the process of getting it al together...Might be nice, if the MAPs work fine to put them up as well in the eventual How-To. that way DIY'ers have all the info at hand.
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ideola  



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PostPosted: Thu Feb 14, 2013 8:48 am    Post subject: Reply with quote

Question: why couldn't you just use the DITC ignition distributor and put the sensor on there instead of going to the trouble to switch in a locked out dizzy? I realize you bought one that was already setup for the task, but I was under the impression that the DITC dizzy could simply have the sensor added to it, since it has no mechanical or vacuum advance.
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Nein37  



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PostPosted: Thu Feb 14, 2013 10:29 am    Post subject: Reply with quote

Any concerns over ignition accuracy with the sensor located on the dizzy. Is there a way to work a different sensor location?
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ideola  



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PostPosted: Thu Feb 14, 2013 11:52 am    Post subject: Reply with quote

Nein37 wrote:
Any concerns over ignition accuracy with the sensor located on the dizzy. Is there a way to work a different sensor location?

Yes, you could also use one of my trigger wheels and mount a VR or hall sensor there.
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Joes924Racer  



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PostPosted: Fri Feb 15, 2013 10:53 am    Post subject: Reply with quote

MSD has a cool unit.
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jaspervanweerd  



Joined: 03 Dec 2012
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Location: Netherlands

PostPosted: Mon Feb 25, 2013 6:02 am    Post subject: Part 2 folks: Reply with quote

I ended up showing you how to install the MSD 6530 and get the car running. Now I will show the steps I’ve made to make the car drivable. But before I do that, I want to address a problem I described before, the FRP (fuel pump relay).

Turns out that, although the tach works, the MSD output signal will not trigger the FPR. One can overcome this by purchasing a so-called MSD tach adaptor and installing that as well. However, I didn’t feel like it and pursued an alternative option (for the time being). I made a wiring loam that makes use of a standard relay to trigger the fuel pumps via a switch, see diagram.





Of course everything nicely wrapped in electrical tape. The switch has three options I, II and 0 (off). Option ‘I’ lets the fuel pump run when ignition is on, ‘II’ is always on and ‘0’ always off. Moreover, the ground for the relay is the boost cut-off switch/sensor. The metal connectors, still form the MSD package, are used to insert into the fusebox directly. Of course using thick wires handle the current. Funny enough the switch I had lying around snugly fit into the inspection hole underneath the steering column, see picture.



Also I rooted the wiring for the dizzy pick-up along the firewall so it can act as an magnetic shield...
But before showing the spark map I used etc etc…let’s ‘enjoy’ the fruits of my labor (also cleaned up the interior and mended any problems).

One of the few 931’s without a cracked dash or torn seats (and that for only 1750 euro's )


Hidden away….




Spot the differences


Ok, full advance !!!
I based my values on the spark map I deduced from the DITC performance graph and included the Air Intake Correction. Assuming point 2 is 9* BTDC <900 RPM.

Also see:
http://www.924board.org/viewtopic.php?t=37214&highlight=programmable+ignition

This is the map I deduced and the MSD curves that correspond to that, feedback welcome !!!

Spark map, with vacuum advance included:





To set full advance, in my case 43* BTDC, we need to mark the flywheel. My lowest value is 18* BTDC and using 25* of MSD retard we end up at 43*. So if we initially set 18* BTDC i.e. 130 tooth / 360 x 18 equals 6.5. So at 6.5 tooth we find 18* BTDC. This you can easily find by manually cranking the engine. In my case an indentation at 9* BTDC is included next to a Z1 mark for TDC. Simply crank and count and mark the number 6 tooth with Tipex. While running the engine you can set ~6.5.
Then with the engine at operation temp slowly increase the run retard in the MSD software with steps of 5* and re-adjust by turning the dizzy to the 6.5 mark using a timing light connected to spark lead one. Might be that you need to tweak the idle RPM a bit using the idle bypass screw on the throttle body. You keep doing this until you reach 25*. Fasten the dizzy lock-down bolt and upload the MSD run curves. Now the fun can begin again, happy driving. In my case I found some lean jetting to occur and therefore I needed to adjust the Air Fuel Ratio. I will do this more accurately at our local garage that has a CO meter. Still I had I nice Sunday drive, ooow I missed that turbo whistle.

Performance wise I do not notice much of a difference compared to the DITC days, starting seems to go a bit better though...

I would really like the EFI people to comment on my spark map. I tried my best to come up with one that approximates the DITC ignition map. For the time being I only want a DITC mimic, the dyno period will come at a later stage...

Any comments/suggestions are most welcome. I will make this a bit nicer in a How-To format ASAP !!

Cheers,

Jasper
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Raceboy  



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PostPosted: Mon Feb 25, 2013 5:18 pm    Post subject: Reply with quote

It seems OK and I wouldn't advance it further at WOT due to not having an intercooler (my car has). Perhaps to be sure the engine is not knocking, you should fabricate det cans..

As for idle, my car runs ITB's and thus the idle vacuum was ~65-70 kPa, usually 931 has ~40-50 kPa vacuum at idle so you should tune the idle area to get the best results (=tune advance so the engine has highest vacuum which means strongest idle).
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jaspervanweerd  



Joined: 03 Dec 2012
Posts: 22
Location: Netherlands

PostPosted: Mon Feb 25, 2013 10:56 pm    Post subject: Reply with quote

Raceboy wrote:
It seems OK and I wouldn't advance it further at WOT due to not having an intercooler (my car has). Perhaps to be sure the engine is not knocking, you should fabricate det cans..

As for idle, my car runs ITB's and thus the idle vacuum was ~65-70 kPa, usually 931 has ~40-50 kPa vacuum at idle so you should tune the idle area to get the best results (=tune advance so the engine has highest vacuum which means strongest idle).


Ok, thanks !!!
What do you mean with det cans, ITB ? One point I am concerned about in my spark map is the fact I use 18* at idle while the stock map uses 9*. Would it be better to stick with 9*, I use RON 98?
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