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Wiring Megasquirt 2 for Stock 76 Dizzy.


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Hello all. So I recently picked up a new 1976 280Z Non CA. It has a few mods to it. Stage III schneider cam, headers, monza exhaust. Something failed on the EFI and the previous owner cracked open the AFM and tweaked a bit. This is causing the engine to run extremely rich. The coolant temp sensor is dead also. I've decided after seeing many split wires and splicing that it would be best to start new with Megasquirt. I plan on purchasing the MS2 3.57 assembled unit and wiring harness. 

 

I know this question strays from the normal. I know the option of going to a 82-83 dizzy. As of right now, I just plan on running MS2 for fuel only. I know there is a trigger input that comes into the ECU like the stock setup. Is this acceptable for the MS2 or can I not use this. My understanding is that the injectors fire on every third pulse. Looking through wiring diagrams I put together this diagram.

 

rS7yKoEl.jpg

 

The 1976 datsun looks like it uses a dual coil setup with a transistor ignition box. Can I still have the megasquirt hooked up with this setup or will it not like it? Any advice would be greatly beneficial.

 

 

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 This is causing the engine to run extremely rich. The coolant temp sensor is dead also.   The dead coolant sensor will have the biggest effect on running rich.  Fix that and things will get much better. Many engines won't even run if the coolant circuit is disconnected because of the extra fuel.  Check the resistance versus temperature of the sensor circuit at the ECU connection.  Charts are in the FSM.

 

I've decided after seeing many split wires and splicing that it would be best to start new with Megasquirt. I plan on purchasing the MS2 3.57 assembled unit and wiring harness.  The harness is full of splits and splicing from the factory.  Not necessarily from an OP.

 

 I just plan on running MS2 for fuel only. I know there is a trigger input that comes into the ECU like the stock setup.  Fuel only is the original usage for Megasquirt.  Spark control came later.

 

My understanding is that the injectors fire on every third pulse.  Another term for that is batch injection.  MS will work the same way if you use the distributor as the trigger.  Every third spark is just one crankshaft revolution.

 

The 1976 datsun looks like it uses a dual coil setup with a transistor ignition box. Can I still have the megasquirt hooked up with this setup or will it not like it? Any advice would be greatly beneficial.  What you're seeing is actually dual pickups and ignition module circuits diving one coil.  It's an emissions control feature, adjusting the ignition timing to give lower emissions during warm-up.  You'll lose that but with MS you can tune around it anyway.  Many people remove the second pickup on their stock setups.

You've probably already figured out much of this since you're using the tons of information that's out on the web.  I added some comments above.  Should be pretty easy for you to use a single pickup from your stock distributor to trigger MS and get going.  But if you fix the coolant temp. circuit you'll have more time to plan.  Although the performance cam will, from what people have said, make the engine run a little rougher with the stock EFI.  The stock EFI ECU is tuned to a specific set of engine hardware.  The cam might be the real reason to go MS.

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I know that the dead coolant sensor will make the car run super rich. I tried unplugging the CSV but it sill floods. To my undertanding that is where the extra fuel comes from for the cold start. Does it increase the pulse for all of the other 6 injectors?

 

The harness has no factory colors anymore. It looks as through the whole harness was redone. All the wires are white!

 

So there is a possibility of using the stock '76 distributor with only one pickup? I know the coils are R/G or B/G. Is this part of the GM HEI I keep seeing?

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Yes, it increases injector open duration based on temperature.  The CSV has nothing to do with the ECU's fuel program.  The CSV is only opened when the starter is spinning.

 

White is not stock.

 

Yes, it's described in the Megamanual.  Here's a couple of starts, you'll have to dig around.  The GM HEI is a different way to create spark, but MS doesn't need to know how the coil is controlled.

 

http://www.megamanual.com/v22manual/mfuel.htm#ignition

 

where the above came from - http://www.megamanual.com/mtabcon.htm

Edited by NewZed
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Ah. Too late to go back to stock now. I just ordered all the parts! :D 

 

I'm just going to state that I have no clue how distributors work. I've built subaru motors but coil on plug is so easy. I'm really trying though. It seems as though there are many ways.

 

I think I have three options

 

1.

From what I learned, the '76 dual pickup coil has two Variable Reluctors (VR) that are wired to the transistor ignition. (ignition module?)  Seeing as I would be wiring only one of the two pickups. I would be looking at needing a new ignition module to just run the single? This drives the tach in to the megasquirt thus controlling fueling?

I would assume with this that vacuum and mechanical advance would still be active, The only use for the pickup is driving MSII and the tach.

 

 

2. If megasquirt can act as the ignition module. The MSII VR sensor can take in a lead from one of the pickups. This would drive tach and MSII fueling. Megasquirt would in return drive the HEI which would step up the spark driven by the coil. The timeliness of that signal will control spark? 

Of course I would need to get rid of vacuum and mech. advance (Weld?) for this

 

3.

Alternatively if I want to run MSII with spark control I may need to upgrade to the '82-83 turbo distributor as it has an ignition module on it. The output of that ignition module would trigger the MSII and then I could wire a HEI out from the MSII to control the spark from the coil?

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With megasquirt, there is no need for the HEI module anymore. The on board BIP373 transistor can handle driving a single coil. I really see no reason why MS2 shouldn't control the spark on a modern setup as the the timing control is superior to a mechanical/vacuum advance. There are a few other threads about locking the distributor and driving all the timing with the MS2. Ultimately, if its the wiring that is keeping you from going from fuel only to controlling both, its really just one more wire (and some ineternal mods).

 

I think you have some confusion on ignition modules or what some call ignitors. The pickup in the distributor tells the ecu or MS2 where the crank is located. In turn, through tables and calculations, the ECU decides when to fire the spark. The processor in the ecu can't drive a coil directly due to current limitations, so it uses a series of transistors to amplify the current handling. The last transistor in this series is the one that is attached to the coil, or the ignition module. I use a nissan unit designed for DIS or coil on plug. The internal BIP373 chip can do it as well. The instructions for a HEI is really left over before they implemented the V3.0 boards. Now it has "native" support without the extra stuff like HEI or even EDIS if you wanted to go MS3/MS3X route.

Edited by winstonusmc
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What is keeping me from wanting to go to full ignition control is buying a 83 turbo dizzy. Prices seem like they are rediculous for just a distributor and then I need to find the base. Does the notch match the '76 dizzy?

 

I did pickup one of the v3.57 boards so it should have the bip373 chip in it? I haven't recieved it yet do I can't check.

 

Edit:
DIYAUTOTUNE states

  • 5 volt ignition output (JS10 jumpered directly to pin 36) for EDIS, Bosch 124, or GM HEI ignition control
  • Slot for installing a BIP373 (not included) for direct coil control

So unfortunately it looks like I would need to solder on a bip373. I picked up the assembled board. I'm horrible with solder. Fine when it comes to wires but not boards. 

Edited by chipndip829
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Pretty sure that your stock 76 distributor will work.  Locking the distributor advance mechanisms would allow MS to fully control timing based on intake manifold pressure and RPM.  The VR wheel in the distributor is no different than a VR or HAll effect trigger on the crank, aside from higher accuracy at high RPM.

 

You're getting closer to the point where you won't need to follow someone else's instructions.  The DIY site has many incomplete writeups and broken links.  For example, the one below.  They're grown too fast.  You just need to sift through the information and figure out what the fundamentals are for each of the various writeups and just figure out how to supply the board and software with what they need to work right. 

 

Many people try to do more than they need to do from the start.  Like COP with a crank trigger.  Not needed for ignition control, but it's pretty cool if you can get it done.

 

https://www.diyautotune.com/tech_articles/megasquirt_ignition_control.htm#fuelsparkdizzy  (Missing links and text that says "this page will be continued" but it never has).

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I finally got my order in from diyautotune. A few mishaps but hoping they get back to me quick. It looks like the 10' harness that I ordered is missing the pins for the fuel pump relay and the ignition out. These pins are 37 and 36 respectively. I need 36 to trigger the coil right? I couldn't believe that they were not part of the harness!? Did I get a bad one?

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Diyautotune has resolved the issue. The harness was supposed to have these pins. Great company if you are looking to megasquirt your Z.

 

That being said I am back in track on my build. I tried to lockout the dizzy. I used thin metal wire. I'll see how it holds up. I would have welded it but I couldn't find a place to get the tip into.

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I did end up dissembling the distributor but it looks like the plate with two holes that goes on the two magnets seems like it  always stays with the top half. I can't see a way to weld itto the magnets.  I'm still N/A at this point so COP doesnt have much benefit as just a simple advance table. I'm looking for a reliable EFI system. I'm surprisingly not doing that bad on the build. The figures are right where I expected them.

 

The good news is that I finally got the megasquirt in the car. I chose to mount it in the passenger side. I took suggestions and grounded everything to the engine and NOT the battery. I ran my relays for the fuse block and one for the fuel pump. I am able to turn on the MS2, communicate(burn), turn on and off the fuel pump, and test both injector banks. Things are looking like they are going smooth. I have an order for a LC2 WB coming, IAT, and CLT. Those should be the last components I need other than the HEI!

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A little update on the build. Megasquirt wiring was cleaned up quite a bit, I have working relays and fuse panels now, Yay for not burning up wires. Once it's running I'll go back and cut to length and make it look factory.

 

I went to a buddys shop and he was able to weld my distributor up. So now I have fixed timing using only one of the coils. I purchased the GM HEI 7 pin and did the mod per diyautotune on the ms2 3.57. I'm getting in the final stretches of the project.  Here's to hoping that it all runs when it's back together.

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  • 2 months later...
  • 7 months later...

I ended up ditching the whole system as it was really not worth it. I bought a crank trigger kit from hoke performance(worked amazing) and bought the quad spark so that I could control an edis 6 coil pack. The setup worked really great but my engine blew a head gasket. I'm in the process of tearing the whole system out and selling it as a whole. RB25det here I come!

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^^^^HAHAHAHA! That is priceless! I was reading through this thinking I was going to post : "You know, a couple of trigger magnets glued into your  flywheel or a trigger wheel on the front pulley and you can just skip cobbling this all together..."

 

Just keep this in mind:

The RB25 will explode too, if you detonate.

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  • 1 month later...

^^^^HAHAHAHA! That is priceless! I was reading through this thinking I was going to post : "You know, a couple of trigger magnets glued into your  flywheel or a trigger wheel on the front pulley and you can just skip cobbling this all together..."

 

Just keep this in mind:

The RB25 will explode too, if you detonate.

 

It definitely can but I'm doing all in my power to keep that from happening. Forged internals, mls hg, arp studs etc...

Yeah the hoke system is a lightweight pulley with a laser cut 36-1 disc attached, bit more reliable than glued magnets. It solved all the issues with trying to use the dizzy, which I admit was a stupid idea from the start.

I'm liking the tuning options presented to me with any of the offered plug and play ecu's for the RB. Boost per gear, dual knock sensors, sequential fueling.

This was a long time coming, just the failed head gasket was the nail in the coffin, also the fact that its freezing where I am = no more z weather :(

The headgasket wasnt from detonation, it was actually a "new" engine that I assembled but stupid me being cheap didn't replace the head bolts. Leaked on first start. Tore the engine out initally to cure a leaky oil pan. :o

 

Hud,

sending you  a PM

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