MSD DIS 2 intallation guide

[jasaircraft]

Ok,

So I have my 99stiGC8 rally car already running fine with the LinkG4+, Now its time to install the MSD DIS2 ignition system.

I have left the wiring to the way it appeared to me as "correct" and it is as follows:

Note: Stock 99sti gc8 wasted spark coilpack has built in ignitors. MSD people told me I had to have an igniter drive the DIS2 (ie. ECU>igniter>MSDDIS2>coilpack)

So I left a 98gc8 igniter ready for use that is between the ecu and the msddis2 box.

Quesiton: Is it possible to run the msddis2 box directly with the linkg4 ecu?

I used the ignitor option because it was easier for the mechanic to just swapp those things in case of a faillure than to get into the software and change settings.

cheers! 

Jose

 

[sardengineering]

Good day.

Please note that CDI installation don't need ignitors, ignitors are used to prevent the fly back from the collapse of an inductive coil and in addition there's a manual cap (limit) on the maximum dwell the coil can receive. 

While I'm on the same topic, please note that CDI boxes are not to be used with smart coils, only dumb coils which don't have internal ignitors. The reason for this is that the coil used with a CDI box must act like pulse transformer rather than an energy storage medium as with an inductive discharge ignition system.

Things to be mindful of when using CDI boxes is the trigger edge the box should be receiving from the ECU, in this case the G4+.

Should you need any other assistance please feel free to follow up at your convenience.

Oh and please do take care when identifying whether your wasted spark coils are dumb (without and internal ignitor) or smart (carrying an internal ignitor). If I recall correctly the coil packs sitting on the intake manifold either carry 3 pins if they're dumb or 4 pins if they're smart.

Cheers!

[Dave Kriedeman]

Hi Jasaircraft,

yes you can control the MSD DIS 2 direct via the ECU .

For example ignition output 1 from the ECU will go to Trigger 1 on the MSD DIS 2.

Also the Ignition trigger firing edge for MSD products is a positive or rising edge.

Regards

Dave.

 

[jasaircraft]

Hi, 

the stock coilpack has built in ignitors on the 99sti... im not using that coil, Im using a similar coil but without built in ignitors from msd (dodge neon coilpack)

I had emailed the msd guys and they replied to me that on a completely stock car for example, I would have to wire the msd post ignitor ie ECU>Ignitor>DIS2>coilpack

And thats what I did, I wanted to keep it simple for the mechanic and not have to swap setting from falling to rising on the linkg4+ ecu.

I have just tested and have no spark, placed a logic probe on the wires going the msd coilpack and see a very weak and quick ground pulse (different to the stock ignitors clear strong ground pulse)

So what coul I be doing wrong?

MSD LED puts out code 3 (intermitent pulse trigger signal)

[jasaircraft]

the 2 channel ignitors negative pulse is good and clear (98subaru ignitor)

[sardengineering]

Hello Jasaircraft.

I can appreciate your attempts to keep things simple and straight forward, but Dave's advisory is actually spot on correct. I am very sorry for any confusion with respect to the instructions issued by the MSD support staff, we aren't here to contradict. Dave's response as well as mine were based on the theory of Capacitive Discharge Ignition systems such as the unit your as using from MSD. CDI works fundamentally different with respect to Inductive Discharge Ignition, which was the OEM solution. To switch between you must expect components to change and to be replaced as well as a difference in the install procedure.

The easiest approach is just as Dave explained, the ignition output from the G4+ > MSD inputs > MSD coil inputs > lastly terminating the spark through the plug wires then to the spark plugs. What you have to be mindful of is the trigger edge coming from the G4+ and what is the trigger edge the MSD box is looking, they must match up. For this install, it might be best to build up a fresh harness to go between the G4+ and the MSD DIS-2 as well as the MSD DIS-2 and the coil pack. It sounds more labor intensive than it really is. Also, I know it might sound like a big ask but you should at the very least understand and be able to follow the installation through. This way you can both diagnose and accept support to diagnose any problems.

I wouldn't be measuring the signal coming from the CDI box to the coil as this is an extremely high voltage spark energy signal. Remember that in a CDI installation the dumb coils only act as pulse transformers, they neither store nor amplify; the spark energy comes from the collapsed capacitors inside the CDI box. Within the OEM solution, an Inductive Dischage Ignition was used and just as the name implies it functions on the inductive principle. The coil has both a primary wound and a secondary wound, the collapsing of these wounds takes a low voltage high current signal and turns it into a high voltage low current signal which terminates at the spark plug as high spark energy. So the same coil works in two different ways.

In hindsight, you may use an oscilloscope to verify the ignition pulse coming into the MSD DIS-2. Coming out of the MSD DIS-2 and to the coils, I would use the inductive clamp of a timing light. I am terribly sorry the solution isn't straight forward enough to resolve immediately, but when I get back to my desk (time difference) I can verify the settings on the G4+ for you. Where to find the menus and what the values should be.

Looking forward to your success mate, cheers!

[jasaircraft]

Thanks Sardengineering,

My main concern is if for any reason the DIS2 unit or the msd coilpack (specially the dis2) decided they dont want to work anymore (it has happened to quite a bit some people after some research) it would be best for stuff to be easily swappable. Since I wont be always available at the assistance point while rally racing takes place in many locations, this situation would present a big problem.

Therefore, I think I have a solution for this. Turns out MSD makes some ignition adapters or ignitors. I think these could give a hand. I say this because people with stock engine management systems (some subarus out there too) have managed to install the DIS2 succesfully.

In these stock ems systems obviously you cant change the output edge, or any other setting, so this should be the solution.

I tried the "checking for spark" procedure from the msd manual, where instead of the ignitor provided the pulsed signal, you manually pulse it on the green/white wires (while ignition on of course) and I still dont get any spark.

I tested the coilpack directly manually pulsing ground and it works fine. So the issue is with the DIS2 box.

[sardengineering]

I am sorry to hear that your CDI box was the source of your grief, however, in the same breath, I am happy your were able to follow logical steps to diagnose the fault. That by itself is a win!

For CDI boxes I would advise either the 500R from Autronic or the vast range of boxes from M&W, when it comes to CDI boxes reliability is everything. Believe the units you are speaking of convert the incoming triggers to the correct edge, or so it would appear based on your brief explanation.

For your described scenario, and for most racing applications it's quite normal to use by-pass harnesses. The G4+ won't be able to power the dumb double ended coil pack, and ignitor will be needed for that. Like you said, for the given instance a solution with a quick release harness by-pass can be implemented with no changes to the G4+ itself. It's been years since I last installed a MSD box, surely there must be a viable solution which works for you.

It sounds as though you have a much better understanding of the task at hand, especially the specifics you require the installation to offer. However, should you require any further assistance getting your G4+ to fit and suite your installation better please feel free to make follow up posts at your convenience.

Thanks for using the Link brand, cheers!

[Dave Kriedeman]

Hi Jasaircraft,

I do not quite understand your concern sorry.

I have run many ViPEC and LINK ECU's with CDI units without issues.

With MSD they require a Positive or rising trigger edge, if it is left at negative or falling the timing will change incorrectly with an increase in RPM.

So for example if you are running 4 cylinder with wasted spark , you will be using IGN OUTPUTS 1 and 2 only.

These will go directly to the trigger inputs 1 and 2 on the MSD DIS 2, The wiring for the coils will go directly to the coils from the DIS 2.

You must use INDUCTIVE STYLE DUMB COILS, with CDI units, however you CAN use NON INDUCTIVE coils by simply reversing the polarity of the coils. 

Please find attached a screen shot of the settings in PC LINK you need to set.

Regards

Dave.

Edited November 14, 2015 by Dave Kriedeman

[jasaircraft]

Thanks guys, I will use all the info you gave me, today we tested the car at the rally track and it was all good. We had trouble with the exhaust manifold not holding up to the antilag heat.

We also have very high IATs around 95degC with ic spray on all the time and 125degC without.

We tested the car with the stock coil. I will be testing the msd later. I had the G4+ datalog key parameters and studied them after some laps, very nice datalogs.