8 replies to this topic

[T-Harps]

Hi There,

Hoping to get some help from you megasquirt experts out there with getting spark on my car. I've been troubleshooting for a couple weeks now and can't figure out what the issue is.

I bought the MS1extra setup from a guy on one of the facebook groups. Have it set up on the G54B and everything seems to be working except for spark. I have attached a wiring diagram of the spark setup below. It uses a Chrysler wasted spark coil that is driven by two GM 4-pin HEI modules. Also posted my spark settings from Tunerstudio. I did briefly have some sparking when I was testing resistances on the HEI modules but nothing since. Here's what I've tested:
- Confirmed 12V at ignition coil and HEI modules
- Confirmed continuity from HEI to coil pack grounds
- Confirmed primary and secondary coil resistances
- Confirmed tunerstudio is seeing missing tooth on trigger wheel

[markhansenconquest]

talk to SCOTTYSTAR on here he does all that stuff on HERE...............

Edited by markhansenconquest, 12 January 2021 - 10:08 PM.

[scott87star]

I saw this when you posted and am only getting around to commenting now because, well, that's a weird way to run the coils.  Cheap yes, but also weird because the GM HEI modules were designed to read a variable reluctor (VR) signal from the distributor pickup.  Same signal that we get from our factory coil.  Problem is, MS can't put out a VR signal, not MS1, 2 or 3 no matter what board.  It can only put out either a 5V or 12V square wave and while I have used a circuit designed for VR to accept a square wave before that circuit had the ability to adjust the internal resistance via an adjustable pot and the GM HEI modules are what they are, no adjustments.  This is the very first time I've seen something like this and I've been through every documented way to run a coil using an MS system several times.  Not saying you can't make it work or the previous owner didn't have it working, just new to me.

So, if this was on my workstation I would first test to see what was coming from the blue/white and blue/red wires when the motor was being cranked over.  You really need an oscilloscope to test as the signals are likely 5V square wave about 3 mS in duration, way to fast for a DVM.  Once I found the ECU is trying to fire a coil then I'd move to the HEI module and look at if it were grounding the coil for that same duration, again a scope is about the only way.  If the ECU isn't sending a signal then you move inside the case and take a look at the circuit that was built for ignition outputs, there will be two of them.  If you can't find a scope you can build a LED circuit that lights when grounded at watch that, it at least tells you something is active.  If you have output from the ECU and the HEI module isn't grounding then I'd say the HEI isn't appropriate for this application.  If you want to send me the ECU and HEI modules I can test, PM me.

[psu_Crash]

I think the best option here is to ditch the HEI modules and just run a dual DIS ignitor.
I use this in wasted spark mode, driving a coilpack similar to yours.
https://www.jegs.com...owaAkX8EALw_wcB

[T-Harps]

Thanks for the answers guys. I knew it was a weird way to run them when I could barely find any info on the web. There definitely is something coming from the MS spark output wires, I can see the voltage jumping around on the multimeter, not sure what the signal is though.

I would happily spend 100 bucks for a simpler setup that works. What's the deal with that Dis Dual Coil Ignitor? Will it take the standard MS spark output and trigger my coils directly?

[psu_Crash]

Yes. The ignitor will trigger from an MS square wave signal. Which you already have. Going from memory I'm not sure if any circuit mods to the MS were required, but I don't think so. I'm sure Scott will replay back too. Been a few years since I did the install so I'd have to reference my notes.

Edit: Thinking about this more today I have some recollection of adding NPN transistors to trigger the ignitor. Could have very well been for a different ignition setup though ... I've run to many variants. I'll try to remember later to grab my notes and let you know exactly what I had to do.

Scott may be able to hook you up with one of these units from DIYautotune at a nice price too.
https://www.diyautot...nition-module/
Does the same thing as the part I listed above, aside from 4 channel vs 2, so it could run a sequential setup with individual coils. Still fine for wasted spark. This one was specifically designed for guys like us though. So you get very nice documentation with it.

Edited by psu_Crash, 15 January 2021 - 12:10 PM.

[scott87star]

The Quadspark is a nice piece, just ordered one for another client to build into the same type of system you're trying to run, dual coil waste spark on a four cylinder.  There are four circuits in one as crash mentioned, consider it two spares if you ever happen to fry one (happens most often during firmware updates when you don't unplug your coil).  Be aware that they are on back order, the note I received when I placed the order was they are in production but not expected until the end of January.

[T-Harps]

Sounds good, I'll put in an order for the quadspark. The documentation says:
Hardware mods required:

• If the board already has any ignition outputs, remove them
  
• Get a 100 ohm 1/4w resistor and cut the leads down to about 1/2″ at each end. Maybe a bit less.
  
• Tin each end of the resistor with a bit of solder.
  
• Cut a 5″ piece of hookup wire (22ga is fine) and strip just a 1/8″ or so. Tin the stripped wire with solder.
  
• Melt the tinned wire tip to one end of the tinned 100 ohm resistor tip and let it cool.

• Heatshrink wrap this wire/resistor assembly.

• Use this wire/resistor combo to jumper the ‘top’ (top as in when you facing the silkscreen side of the PCB, with the text so that you can read it normally) lead of R26 to IGN on the opposite side of the PCB on a V3.0, or the center hole of Q16 on a V3.57. (On a V3.57, this is kind of tricky. It’s easier to use pin 7 on the U1 socket instead, on the underside of the board.)
  
• Run additional resistor-on-a-wire combinations for each spark output.

I'm thinking my ECU probably already has these mods, but i'll take a look inside anyways.

[psu_Crash]

Sounds like you have a plan. That should clear up the spark issues for sure. Looking forward to your progress!